Home / 9.6: Genetic Markers & Physiological Characteristics

9.6: Genetic Markers & Physiological Characteristics

Genetic Markers

Introduction – Genetic markers is a gene or DNA sequence with known location on chromosome that can be used to identify an individual or species.

As per Crawford (1973), these are essentially genetic entities segregating independently, & used to classify population by their presence absence or differences in frequency among population.

Human blood is an important source of genetic markers & it has advantages as it is easily obtained & can be easily transported

Common types of Genetic matter are blood groups system, VNTR (DNA Fragments etc)

Uses

  • to study the relationship b/w an inherited diseases & its genetic cause (mutation → defective gene)
  • Pices of DNA that lie near each other on a chromosome tends to be inherited together. This property enable the use of marker to understand precise inheritance
  • Pedigree Analysis – Genealogical DNA testing as well as uni-parental testing (mitrocondrial  or Y Chromosome) to understand inheritance
  • Tracing pattern of migration
  • Understanding interplay of heredity & environment

Blood as Genetic Marker

Introduction – Medically significant blood polymorphism include 1. ABO blood group System, 2. Rh blood group 3. HLA System

They Act as Genetic Markers B/c

  • All individual in human populations re not one & the same
  • Obey Mendelian rules of inheritance.
  • Frequency is different in different population i.e Huge variation
  • Relative frequency add up to 1
  • Genetically grounded not role of Environment

Along with above – Easy to obtain & Easy to transport to laboratory. So they are considered as good genetic markers

Types of Genetic Marker in Blood

  • Genetic Markers on Blood Cells
    • Red Cell Antigens
      1. ABO System
      2. MNS System
      3. Rh System
    • Hemoglobin
    • G-6-PD Enzyme
  • Genetic Marker in Plasma (Serum Protein & Serum Enzyme)
    • Haptoglobin
    • Transferrin
    • Albumin
    • Globulin
    • GM Factor etc
  • Human leukocytes antigenes (HLA)

Conclusion – Thus, blood group, as genetic markers, are quite valuable in classifying population groups ; for paternity testing & for working on genetic linkage.

ABO Blood Grouping & its Uses

Introduction – The ABO system is blood group system based on the inherited properties of RBCs. it was Landsteiner in 1900-02 discovered the ABO blood group system, but their mode of inheritance was established only in 1924 by Bernstein.

Principle of ABO Blood Grouping

  • ABO system is determined by multiple allelism – i.e the inheritance depends on three alleles, A,B and O – these genes are located on ABO locus on long arm of chromosome number 9.
  • These three segregate to form six genotypes – AA, AB, AO, BB, BO, OO & four phenotypes – A, B, AB & O
  • Blood group Antigens are str present on the surface of RBC membrane which react with serum of other individuals causing clumping/agglutination are antigens. – It form basis of ABO blood grouping
  • Normally if a person has an antigen in his RBCs, his plasma has natural antibodies against the other antigen. Ex. Anti A, Anti B
  • The blood groop, antigen-antibody reaction is CA leed isoagglutination. Based on this blood group of individual can be determined, with the help of standard antisera are available.

Use As Genetic Markers – They are set of simply inherited variations that are quite frequent in most populations. They are easy to detect & are virtually unaffected in expression by the sex, post natal age, & environment of individual. Thus they are highly reliable markers.

Distribution of ABO Blood Group – McArthur & Penrose worked out the average frequencies for various regions & found that for the world as a whole, the frequencies were,

  1. A (21.5%) – Europe & Eurasia, Australian Tribes
  2. B (16.2%) – North India & Central Asia (-nt in Australian Tribes)
  3. O (62.3%) – America

Latest Studies on Population Distribution (Add only if the question is specifically on Variations in Human population)

  • Type O –
    • >80% in most of the new world. In fact reaches even 100% in some South American Indian tribes.
    • Broad zone of low O frequencies from Eastern Europe across much of Central Asia.
    • Pockets of high O are also found in certain people of Europe, like Basques, Sardinians etc
  • Type B
    • Nearly absent in American Indians & Australian aborigines.
    • It is parent in up to 15% of European & 40% of African, & Asia & India, with a good presence in Himalayan region.
  • Type A
    • Quite high in Europe.
    • Rare or absent in south & Central American, but significant in North American, reaching 25% or more in some tribes
    • Compared to A1, A2 has much more restricted distribution, going mainly up to Europe only (subtype of A)

Relative Frequency of Different Blood Groups

  • O – 47%
  • A – 41%
  • B – 9%
  • AB – 3%

These geographical gradient shows that ABO blood groups  are affected by environmental selection. (I.e subjected to natural selection) –

  • Ex Relatively high ration of the gene for blood group B may occur in the areas of urban civilisation, due to some advantage of its possessors in resistance to epidemic disease such as plague & smallpox.

Use of ABO Blood Group System

  • Racial Classification – In 1946 Weiner proposed racial classification based on the frequencies of alleles for ABO system, MNS System, Rh blood factor & identified six groups of peoples on this basis into Caucasoid, Negroid, Mongoloid, Asiatic, Australian & Amerindian
    • Frequencies
      • Caucasoid – relatively high incidence of A2
      • Negroid – Relatively high incidence of A2, comparatively high incidence of B
      • Mongoloid – High incidence of A1, vary low frequency of A2
    • Boyd informed following  Advantages of using ABO of Racial Classification
      • inheritance is known – a/c to mendelian principle
      • Not altered by diffierences in env.
      • Frequency in population is very stable
      • Probably Arose very early in man’s evolution
      • Considerable Correlation b/w geography & distribution
      • Blood groups are sharply distinguishable – all or non phenomena
  • ABO Blood Groups & Diseases – certain blood groups showed association with certain diseases like
    • Blood group B – plague & small pox ; infant diarrhoea
    • Blood groups O – Ulcer (Gastric & Duodenal)
    • Blood Groups A – Stomach & Pancreatic Cancer, Peraicious Anemia, Ovarian Tumor, Diabetes
  • ABO incompatibility & haemolytic disease – occasionally haemolytic disease of the new born result from incompatibility b/w mother & child → still brith / infant death (may be regarded as mechanism of selection)
    • 2 Types of mating acc to Blood Group
      1. Compatible (Homo specific )
      2. Incompatible (Hetero Specific )
  • Medico Legal Aspect of ABO Series
    • Paternity Diagnosis / Disputes – dispute about wheaten the father of a child is the child’s biological father or not.
      • Role of ABO Blood Group – at least 10-15% of the cases can be solved thr ABO Systems.
      • As A & B are co-dominant & O are recessive. ; on bases on this knowledge, we can find out the possible blood group of a child as in following table   
      • Thus, if a man has blood group O, he can’t be the father of a child AB blood group, whatever be the mothers’ blood group. Other combinations can be found out from the table.
    • Causes of illegitimacy
    • Criminal proceedings – disputed cases of Claimants

Scholars View

  • According to Mourant et al 1958 the world distribution of blood group is better known than that of any other human polymorphism used for studies of paternity, so called rare-Mixture and for distinguishing MZ twins from DZ twins.
  • Alice Brues (1954-1963) shown that world distribution of Blood groups is consistent with the thesis of natural selection. She calculated distribution of 219 representation human population and concluded gene frequencies as:
    • 25% – IA
    • 15% – IB
    • 60% – IO
    • A Blood Group – Max frequency in Lapps (35%)
    • B Blood group : Asiatic People – Monngoloids (35-37%)
    • O Blood Group : High in American Indians

Conclusion – Thus, ABO blood group, as genetic marker, is quite valuable in classifying population groups ; for paternity testing & for working on genetic linkage & understand many genetic principles like multiple allelism, co- dominance, polymorphism, immune reactions and linkages.

RH Blood Group or Rhesus Blood Group System

Introduction -The Rh system is independent of other blood group systems. It was discovered Landsteiner & Weinerin Rhesus monkey & human in 1940. The Rh antigen is also named after Rhesus monkey . Later Fisher demonstrated 3 pair of allele – [C,c], [D,d], [E,e].

  • The alleles C,D, E are dominant & c,d,e are recessive
  • For routine purpose, the typing of person as Rh+ or Rh – depends on the presence (or) absence of Antigen D (or) Rho Antigen on red cells and hence can be accomplished by testing with anti-D serum.
  • D’ is most powerful which accounts for Rh incompatibility reaction & a/c for vast majority of Rh +ve population.
  • There is no natural anti – Rh antibody in the serum. They arise only as realist of Rh incompatible pregnancy (or) transfusion. 

Distribution – Rh system with its eight haplotypes & variety of alleles at each locus gives great scope for variation in frequencies of a selected population. 

  • European – 85 % of population is Rh+ & 15 % of population is Rh-ve
  • Indians – 93% Rh +ve ; 7% Rh -ve
  • RH +ve – Mediterranean, North India, Africa, China, Burma
  • Rh -ve – Europe (16%), Basque community of Spain 30% (& Cde frequency b/w 50-60%)
  • Among different  Races
    • Mongoloids – Rh- is very rare 0.5 to 1.5 %
    • Caucasoids – Rh – is high upto 15%
    • Negros – Rh occurs in 5-8% population
  • Case study : Hemolytic Disease of Newborn, HDN →

Rh – incompatibility – Erythroblastosis fetalis,

  • a condition apparent at birth. It is characterized by excessive destruction of RBCs and a compensatory over development of those fissures (liver /spleen) in which red blood cells are formed.
  • This disease is usually due to a difference of Rh – blood type between the mother and her infant. Since Rh-ve mother is not born with Rh+ve antibodies, it is only after a Rh+ pregnancy (or) after Rh+ve blood transfusions that her Rh+ve fetus run the risk of erythroblastosis fetalis.

Human Leuckocyte Antigen (HLA) System

Introduction – HLA system refers to the gene complex encoding the major histocompatibility complex (MHC) proteins in humans. These cell surface proteins  are responsible for regulation of immune system in humans. The immune system uses these markers to identify which cells belong to body, & which don’t. Hence  is responsible for graft rejection.

  • First work done by Gorer in 1930’s on mice led to the discovery of Major histo compatibility complex (MHC)

HLA Complex of Genes – is located on the short amr of chromosomes 6. – have 5 closely linked loci, A,B,C,D & Dr

  • It consist of 3 separate clusters
  • HLA Class 1 comprising A, B and C loci which determines histo-compatibility wrt acceptance / rejection of allograph
  • HLA Class 2 or D region consist DR, DQ and DP loci which regulate the immune response.
  • HLA Class III (or) the complement region containing genes for complement components C2 and C4 of the classical pathway.
  • It is highly unlikely that nay two unrelated individuals will be identical at this locus. Hence it is apparently clear that unrelated individuals would rarely be compatible to accept grafts from each other without any danger or rejection.
  • Greater the similarities at this locus, the more likely it is that the graft will be accepted / the transplant will not be rejected.

Population Variations

  • frequencies of HLA allele shows considerable geographical variation.
  • A, B, C, D & Dr – loci 17,29,7,11,7 – No. of alleles
  • The HLA complex  is highly polymorphic. The number of alleles known for HLA-A is 32, HLA-B is 55, HLA-C is 14 and HLA-D is more than 85. These alleles are broadly 3 groups ;
    • A2 : frequently high in all population such
    • A1 : present in all but high in some such as in Africans
    • Bw42 : confined to some population such as in Africans
  • Considering the number of alleles, more than trillion combination are possible →  results in large number of phenotypic variations where unrelated individuals are unlikely to have identical HLA phenotype
  • Ex – In some African populations, the presence of HLA-B53 allele has a strong protective influence against severe malaria and the HLA-D allele protects against Hepatitis B infections.
  • Thus, the HLA system with the numerically polymorphic alleles, is outstanding useful for the study of population affinities.

Functions of HLA System

  • Proteins encoded by HLA are unique to every person. They are present on outer part of body cells.
  • The immune system uses these antingens / Proteins to differentiate self cells & non self cells. This results in rejection of graft when there is difference in HLA system of acceptor & donor
  • Infections Diseases : Presenting of foreing antigen to T -cells which kill the foreign antigen.
  • Autoimmunity : Certain HLA antigens are associated with some autoimmue disorder like type 1 diabetes, ankylosing spondylitis, Systemic lupus erythematious etc.
  • In cancer ; HLA mediaed diseases are directly involved in the promotion of cancer. eg. Gluten-Sensitive enteropathny is associated with T cell lymphoma.

Role in Organ Transplantation

  • Transplantation – Arranging of foreign cells tissues, organs into body of a recipient is called as translation / grafting.
  • Histocompatibility – is condition in which the recipient should not show any adverse reaction.
    • This happens when there is antigenic similarity b/w the donor & recipient organ/ tissue.
    • Reaction –  same phenotype → considers alleles present on chromosome more than a trillion combination possible → almost impossible to have same genetic structure → transplantation rejection by HLA system → but high probability of histocompatibility b/w MZ Twins
  • Most important tissue antigen for causing graft rejection are a complex called HLA.
  • Types of Transplants
    • Autograft: Grafts within same individual.
    • Iso graft: Graft from a genetically identical person. Ex: MZ twin.
    • Allograft: Graft within same species.
    • Xenograft: Graft between different species.
  • HLA System is studied
    • to improve the graft tolerance by matching antigens to the donor & receipt.
  • Research says a donor must match a minimum of 6 HLA markers. Otherwise HLA antigens of donor will be destroyed by anti-HLA antibodies of the recipient.
  • graft rejection can be prevented by suppressing immune system by using Gluco-Corticoid hormones which suppress growth of lymphoid tissue etc,

Conclusion – HLA complex is fixed in an individual and varies from individual to individual. The evolution of MHC polymorphism ensures that a population will not succumb to a new pathogen or a mutated one, b/c at least some individual will be able to develop adequate immune response to win over the pathogen.

GM Factor

Introduction – Gm factor refers to serologically detectable variations of certain antibody proteins present in the serum & cells of the immune system, knows as immunoglobulins.

immunoglobulins – Each immunoglobin molecule is made up of 4 Polypeptide chains.

  • Two identical light & two identical heavy chains held together by disulphide bonds.
  • The light chains are of two types: Kappa(K) & Lambda with differing amino acid sequence in ratio of 2:1 in sera.
  • The light chains are alike in all classes of immunoglobins. The heavy chains differ in each immunoglobulin.

GM factor is variant of IgG antibody. When there is variation in constant region of IgG, it is treated as antigen when it crosses the placenta  to baby’s body. This variation is called as Gm factor.

  • IgG is the only antibody which can cross the placenta & it is alos secreted sometimes in milk

Effect

  • If mother has a Gm factor not possessed by her baby, the mother’s IgG antibody will be attacked upon when the baby grows & forms its own antibody.
  • However mother’s antibody which is gained through placenta or milk tends to disappear after first few years of life.

Features

  • It is distributed approximately equally between the intravascular & extra vascular compartment.
  • The catabolism of Ig G is unique in that it varies with its serum concentration when its level is raised in Malaria, Kala azar, Dengue, where Ig G synthesized against a particular antigen.
  • Ig G is transported across the placenta & provides natural passive immunity in the new born.
  • Ig G binds to micro-organisms and enhances phagocytosis.
  • To prevent erythroblastosis fetalis Anti-Rh(D) Ig G during delivery is administered.

Types of Gm Factor : four subclasses of IgG have been recognised

  • (IgG1 (65%), IgG2(23%), IgG3(8%), IgG4(4%)
  • each possessing a distinct type of gamma chain.

Distribution – It has been found that different populations have been characterized by different GM characteristic.

  • Steinberg studied the Gm factors in Sidamo tribes of Ethiopia and Ainu tribes of Hokkaido of Japan.
  • Vos et al (1963) the Gm types distinguish the Eastern Asiatics from the people of India, but show the connection of Mongoloid peoples of North East India to the neighboring East Asiatic populations.

Conclusion – GM factor is an imp. genetic criterion for differentiatiion fo races.

Serum Protein Polymorphism

Introduction -Serum proteins are the proteins present in the blood plasma.  The blood protein which are commonly used as  genetic marker are 1. Haptoglobins 2. Transferring

Transferrin

Introduction – It  is a iron binding beta globulin factors. These are also called as  Siderophilins.

Function – is distribution Fe from site of RBC destruction (after burst of RBCs – 120 days) & intestine to bone marrow for the production of new RBCs (or) to liver for storage in form of ferritin.  Each molecule can bind to 2atom of Fe

Transferrin Polymorphism

  • is determined by many alleles at a single locus in an individual’s gemome.
  • Five transferring alleles were identified TfA,TfB,TfC,TfD and TfE and these alleles produce different phenotypes in different combinations (DC,DE,DA,CB,CA,EA).
  • There can be separated by starch gel electrophoresis.

Distribution

  • Buttner-Janusch 1961 & Goodman et al 1965-67 compared with man, chimpanzees and Macaque monkeys have a comparable (or) even greater variability in their transferrins.
  • Normal individuals exhibit the +nce of only one trasferring band deonoted by TfC – i.e it is most commonly found across populations
  • A slow variant TfD1 is quite common in African populations & Australia – Spl, in Australian Aborigines
  • Most of B variants are infrequent except in Navajo Indians of SW USA.
  • Another variant TfD chi was first described in Chinese and later found in various populations of South East and East Asia.

Haptoglobins (Hp)

Introduction – It is a alpha globulin with the property of binding free oxyhemoglobin that has escaped from the RBCs. It consists of two α and two β chain linked with disulphide bonds.

Features

  • Haptoglobin is produced mostly by hepatic cells but also by other tissues such as skin, lung &  kidney, used to clear free Hb(outside RBCs) from circulation.
  • Function – It transport free hb to liver for breakdown of haem & ultimate production of bile salt, biliverdin,
    • It prevent hb from damaging the kidney by passing through glomeruli.
    • Hp function is to bind free plasma hemoglobin which allows degradative enzymes to gain access to the Hb & prevent loss of iron through kidneys.
    • Since the reticuloendothelial system will remove the Hp-Hb complex from the body.
    • For ex: Haptoglobin levels will be decreased in hemolytic Anemia’s.
  • In some infection & inflammatory diseases, higher levels of haptoglobins are found.

Population Variation

  • Haptoglobin exists in two allelic forms in the human population, so-called HPI and HP2.
  • In 1955, Smithies revognized that the patterns of haptoglobins are not same in all individuals & there are types – Hp 1-1 , Hp 2-2 , Hp 2-1
  • These patterns are inherited & two alleles are involved – Hpy^1 & Hpy^2 alleles
  • Hp if different genotypes have been shown to bind Hemoglobin with different affinities, with Hp 2- 2 being the weakest binder.

Population Distribution -According to Azonedo et al:

  • In blacks in the USA, Brazil &  Africa haptopobin is absent (Ahaptoglobenemia)
  • HPY1 gene is around 40% is W.Europe and about 60-70% in Tropical Africa.
  • HPY1 frequency is found to be low in Asia.
  • HPY2 gene is mostly found throughout the world. Suggest that it was present in early human

Conclusion – Haptoglobin polymorphism is maintained by heterosis. The selective forces at work are not known clearly.

Blood Enzymes

Introduction -Enzymes are protein molecules a in cells which work as catalyst. Enzyme speed up chemical reactions in the body, but don’t get used up in the process.

Blood enzymes polymorphism exists wrt to some of the blood enzymes & hence will act as genetic markers. These are

  • G6PD
  • Adenylate Kinase
  • Red Cell Acid Phosphatase (AP)
  • 6 – PGD

Glucose 6 Phosphate Dehydrogenase – G6PD

Introduction – RBCs get energy by anaerobic breakdown of glucose to lactate. In this process G6PD catalyses the conversion of Glucose6-phosphate to phosphogluconate in the presence of Co-enzyme NADP.

features

  • It helps protect RBCs from damage & premature destruction against oxidative damage.
  • It is  found in many tissues but including RBC & its deficiency, leads to destruction of RBC in certain condition.

G6PD deficiency

  • is heritable disorder & X linked. Casued by single gene.
  • eg, upon intake of bean, Vivia fava (Favism) & malarial durg( primaquine) & the  condition is called as haemolytic anaemia or Favaism.
    • However, G6PD deficient persons of African origin do not get favism
    • but such persons of European origin get it.
    • This suggests that there may be different types of G6PD def.
  • Glutathione Stability Assay or Test – in G6PD deficiency subject’s RBC show low level of reduced glutathione. so the test is used to detect this problem
  • G6PD def. is malaria affected areas of the world suggests that such mutations confer resistance to the malaria parasite.
  • Thus, a defective G6PD confers a selective advantage on individuals living in the environment where malaria is endemic.
  • The frequency of this enzyme deficiency is high in males than females.
  • High G6PD deficiency was observed among Munda(16%), Paraja(16%), Kharia(14%), Santhal(9%), Oraon(8%) etc,.
  • GD canton → G6PD deficiency found in 5% of southern Chinese people
  • GD Markham → low land areas of New Guninea
  • GD Mediterranean → around countries surrounding Mediterranean Sea
  • Other area – Africa, S.E Asia. Indonesian archipelago, Burma, India

Variability

  • The variability in the enzyme G6PD is reflected in rate of migration of the enzyme in an electric field & severity of RBC destruction during intake of certain substances.
  • The normal form is Gd (B+) other variants are Gd (B-), Gd (A+) and Gd (A-).
  • The half life for normal enzymes is 62days.where as half life for Gd (A+) and Gd (A-) is 13 days only.

Population studies

  • B(-) from is prevalent in Mediterranean, Middle East, Greece, India in about 20% population reaching a level of 50-60% in a Jewish isolate. It has same rate of migration but severity of RBC lysis is great.
  • A(+) & A(-) forms are present in 20 % in African population
  • Thiland & micronesian – incidence rate around 10%
  • Individuals with G6PD def. present in Africa, SEA, Indonesian Archipelago, Burma, India, Mediterranean region.

Adenylate Kinase

  • Present in various tissue including RBC
  • Catalyses conversion of ATP (Adenosine tri phosphate) to Adenosine Diphosphate (ADP) to adenosine Mono phosphate (AMP)
  • ATP → ADP → AMP

Population Variation

  • The commonest phenotype is AK1
  • Another allele AK² mostly seen in heterozygous form along with AK1 i.e AK² AK1
  • AK² → 2-5% in European but in African & Asian it is very less.
  • Therefore, with reference to AK the human populations are showing polymorphism.

Red Cell Acid Phosphatase (AP)

  • the enzyme functions to split phosphate.
  • The most common phenotypes are ACP1, ACP2, and ACP1 & the common alleles are ACP1A , ACP1B, ACP1C
    • Most frequent allele is ACP1B , with frequency of 60-80%.
    • The European range for ACP1A is significant. But in African it is considerable low
    • In New world Aborigines, ACP1A varies widely (25-67%).
    • ACP1C , is the least frequent allele.

6 – PGD

  • the enzymes oxidised 6-Phosphogluconate to ribulose 5-phosphate, thereby, generating NADPH (a fundamental metabolite)
  • Two common alleles, PGDA & PGDC are found in population.
    • The frequency of PGDC varies from around 3% in Europe but is rather higher in some African & Far East Populations.
    • It is highly frequent in Bhutan (21%) & South African Bantu (15%)

Variation in Physiological Characteristics

Many physiological characteristics of human population show variations related Age & Sex. They include

  • Hb Level
  • Blood pressure
  • Body Fat
  • Respiratory Function
  • Pulse Rate
  • Sensory Perception

Haemoglobin Level

Introduction – Hb is the protein molecule in red blood cells that carries oxygen from the lungs to the body’s tissues in form of oxyhemoglobin  & return co2 from the tissues back to the lungs in form of carboxy hemoglobin.

Features

  • Metabolic Limits – 35g/l can never rise above this in RBC
  • Composition – Fe containing porphyria ring  + 4 Protein Chains (protein part c/l globin)

Variations in Hb Level

  • Normal forms – 2 normal forms of hemoglobin are fetal Hb (Hb F) & adult Hb (HbA).
  • Mutant forms – three variants HbS, HbC, HbE – are found in fairly large areas of the world at varying frequencies
    • HbS: The valine replaces glutamic acid at sixth position, which turns RBCs into sickle shape.
      • Livingstone et al have studied the sequence of cultural & environmental changes leading to changes in the frequency of the HbS allele in tropical Africa.
      • HbA/HbS (Heterozygous) individuals resist malaria.
      • HbA HbA (Homozygous) suffers from malaria.
      • HbS/HbS suffers from sickle cell disease, which is Lethal.
      • Distribution
        • Many population in the west tropical bell of Africa have the sickle cell Traits, (35% in some communities)
        • Also, high values occurs in few Mediterranean localities.
        • In India, the highest sickling are observed, which may be due to the locally intense malaria.
    • HbC & HbE are the variants of the Sickle cell mutation and are useful for resisting different types of blood parasites.
      • HbC – It is frequent in west African zone centring on Upper Volta & Northern Ghana
      • HbE is prevalent in South East Asian countries including parts of India.
  • Sex
    • Male – 16g/dl &
    • Female 14g/dl (Menstruation & lesser RBCs number  )
    • Allan & Girdwood in 1982 have indicated that an Hb Level of 12g/dl among male considered Anemia whereas it is normal situation among female.
  • Age ( Studied by Owen in 1977)
    • High in infant & gradual increase up to about 30 year of age. eg. America – High value maintained throughout life & starts to decrease only in old age.
  • Population / Ethnographic Variations
    • Indian : Lower than normal
      • Male – 12 g/dl (
      • Female – 10 g/dl (Anemia acc. to Allan & Girdwood)
    • Pearson et al & Owen’s study of nutrional state of Canadian population (Quebec )
      • Male at 10-14 years ; 13.5 g/dl
      • Female at 10-14 years : 13.5 g/dl
      • Male at 20 years : 15.3 g/dl
      • Female at 20 years : 13.5 g/dl
    • American Study
      • Prepuberty M – 13.9 g/dl
      • Prepuberty G – 13.8 g/dl
      • After Puberty M – 15 g/dl
      • After Puberty F – 13.3 g/dl
    • Great Andamanese population (Studies by Verma) both M & F are anaemics – 30 %
    • Chatopadhyay -Found that 50 % Female anemic,No male anemic, children M – 57% Anemic; Children F – 62 % Anemic
    • Pandey et al : Oranon Tribe Anemia – 60-74 %
  • Cultural Variation
    • The cultures which demand higher activity levels have selective pressure on higher level of hb
      • In the inhabitants of high altitudes and in persons of doing exercises the % of Hb rises.
    • Nutritional levels also depend considerably on culture, which thus further influences Hb level.
      • Very high in Arabs due to iron rich diet such as dates & dry fruits
      • High in agricultural community due to vegetables
      • Low in pastoral community due to milk
    • Traditional practices such as Clitorectomy & Circumcision in some communities are also often responsible for the anaemia of infants & women.
  • Developed Nation > Developing Nation – d/t nutritional pattern is socio-economic a status is better & hence diet is better in developed country.

Hypothesis of secular trend in HB level

Rise of HB level currently, even in primitives, is greater than the level prevalent in advance societies several centuries ago. This trend is true of all ethnic groups

Reason of Ethnographical diversities in Hb in different Population

  • Relative influence by activity of the population
    • High activity culture → high selective pressure on high level of Hb
  • Culture & Socio economic Statues also influence

Importance of HB Level Studies

  1. Anemia
  2. Abnormal HB – Sickle Cell Disease

Thalassemia – are inherited blood disorder characterized by abnormal hemoglobin production causes anemia. Hemoglobin is made up of two types of proteins Alpha (α), Beta (β).

  • Alpha thalassemia: Major people whose hemoglobin does not produce enough alpha protein have alpha thalassemia. It is commonly found in Africa, Middle East, SEA, S.China, etc,.
  • Beta thalassemia: People whose hemoglobin does not produce enough beta protein. It is found in mediterrian desserts, such as Italian and Greeks, Arabian peninsula, Iran, Africa,S.China etc,.

Study : Hb Variants in the Population of Northern Region of WB

  • Rajbanshis (survivors of an aboriginal race) – have high occurrence of HbE(92.7%) hemoglobinopathies.
  • Also found among Muslim groups in the area – (as mostly converted)
  • Tribal population (Oraws, Mundas, Santals) – high occurrence of SCA diseases(34.8%) – as migrated to northern district for tea cultivation from chota Nagpur plateau.
  • Whole hemoglobinopathies are lowest (17.5%) among mongoloids
    • show heterogenous distribution as tribal – may be related to inter-community m’age among Nepalis / hill men & tribals for last centuries, due to cohabitation at same places.

Pulse Rate

Introduction – Pulse is the no. of heart beats per minute. any deviation form noramal heart rate can indicate a medical condition. Fast pulse may signal the presence of an infection or dehydration.

It is measured at the wrist, neck, temple, groin, behind the knees or on top of the foot as an artery psses clode to the skin in these area.

Variation of Pulse rate

  • It varies according to the age of persons, whether they exercise or not & other physiological conditions in the body
  • Change in in the o2 pressure, high altitude areas & other metabolic demands on the body may also cause change in the pulse rates
  • Normal Range – 60 – 100
    • < 60 – Brandy cardia (Heart blocks)
    • > 100 – Tachy cardia (Common in Dehydration & infection)
  • For resting heart rate
    • Newborn infants : 100 to 160 beats per minute
    • Children 1 -10 year : 70 to 120 beats per minute
    • Children 10-adult : 60 to 100 beatus per minute
    • Well trained athleltes : 40 to 60 beats per minute
  • Infection / dehydration / exercise – increase in pulse rate

Conditions

  • Tachycardia – resting heart rate consistently high
  • Bradycardia – resting heart rate consistently low

Importance of Pulse rate studies

  • Any deviation from normal heart rate can indicate a medical condition.
  • Fast pulse may signal the presence of an infection or dehydration
  • IN emergency situations, the pulse rate can help detemine if the patient’s herat is pumping.
  • It can give info about the fitness level & health of person

Blood Pressure

Introduction – It is the lethal pressure exerted by blood on the walls of blood vessels while the blood is flowing through them.

  • Contraction of ventricles produces (i.e blood leaves heart)  – systolic pressure – 120mm Hg(100-140).
  • Relaxation of ventricles produces (at this heart receive blood)  – Diastolic pressure – 80mm Hg (60-100)
  • Blood pressure is indicated in fraction ; the upper no. indicating SBP & the lower indicating DBP
    • A rise in SBP indicate increased contraction
    • A rise in DBP indicate decreaded relaxation of the heart.
    • Hypotension Less than normal range.
    • Hypertension More than normal range
  • BP is measured by sphygmo – manometer ;
  • Acc. to Kapian (1978) population can be arranged on basis fo BP variations
    • Normotensive– 100 – 130/60 – 90
    • Moderate– 130 – 160/90 – 100
    • Severe Hypertension– >160/100
    • For the SBP, 100+ Age is also considered normal
  • American heart association (2017) recently, said if BP > 130/80 mmHg be considered medically hypertension which was reduced down from 140/90.

Variation in BP – Researches show +ve corelation b/w BP & age, sex, heredity, body composition & social status.

  • BP varies with Age Groups
    • acc. to age is high during growth & deve. up to adolescence, thereafter is shows a rhythmic variation on a daily basis.
    • Neonates
      • first day – 70/50
      • increase in Bp during next several months to approx 90/60.
      • The rate of increase is higher during this period.
    • Infancy – 70 – 90 mm 
    • Child hood – Hg 90 – 110 mm
    • Post Puberty – Hg 110 – 120 mm
    • Old Age – Hg 140 – 150 mm Hg
  • Sex – in females BP is slightly lower up to the age of 45-50
  • Body Size – in obese person BP will be on higher side
  • Body Condition – Emotion (or) Excitement – high BP

Factors in BP variations

  • based on family studies
    • 16% variation is due to env. factors
    • 48% of additive genetic factor
    • 36% to dominace
  • Heredity is the main cause & env, will act as precipitating factors
  • Dies, stress, strains of life, sedentary lifestyle are important factors for high BP

Population Studies

  • Rular India
    • % of Normotensive – 95%
    • In many cases, % of normotensive & hypertensive has been found to be higher than borderline → i./e majority of population is either normotensive or hypertensive
    • Reson of low % of borderlines :
      • Cardiovscular system has this ability b/c of homeostatic mechanism to sustain change due to stress & stain of env.
      • seems to be threehold limit ; if crossed once, there is no scope of return & normotensive becomes hypertensiv
    • Similar studies – RamiReddy (1995) while studying BP variation in Rural A.P
  • Urban – Industrialised population
    • the % of normotensives is not so high in comparision to hypertesive .
    • Hypertensive are around 5% subject showing increase in both SBP & DBP
    • Small but signigicant group of borderlines.
      • b/c homeostatic mech. are disturbed in such societies due to nutritional & life stle reasons. – absence of green veges & fruits & inclusion of fat to a great extent in diet
  • In both rural & urban populatins, the variations of the BP tend to be lower in the household samples than that of hospital.
    • May be due to natural setting of house
    • free from anxiety & tension

Outside India studies conducted by Boyce Attenborough, Harrison – Thornabrook & Sinneff since 1970 in the population of New Guinea etc. & reached to the same conclusions that. “In addtion to heredity, diet & stress & strain of life are the two most imp. causative env. factors of high BP”

Body Fat

Introduction – Body Fat (or) simple fat is a loose connective tissue composed mostly of adipocytes. It is uniformly distributed in human body & its plays role in warm & cold adaptation.

Dual Control of fat deposition / Level

  • No. of fat cells : genetic control
  • Amount of Fat filled in fat cells; environmental control ( Socio-economic )
    • Nutition level
    • Level of Activity

Definite pattern of subcutaneous fat deposition in Body – High saturation of subcutaneous fat in subscapular region, abdorrinal region (trunk) , arms, thigh & buttock, Calf & limbs

Two Types of body Fats

  1. Essential Body Fat – is used to maintain life & reproductive function. Women (8-12%) have more than men (1-3%)
  2. Storage Body Fat – is used to protect internal organs in chest & abdomen

Role in warm & Cold Adaptation

  • Warm – thin layer of subcutaneous fat
  • Cold – higher fat level

Measurement : Special caliper (Pinching)

Variations – Various Variations related to age, sex, population & ethnic groups are found with respect to body fat which is both due to genetics & env.

  1. Age Related Changes
    • Fetus at 34 weeks – Body fat begins to be laid & increase until birth & attains peak by 9 months of age
    • 9 months to 8 yrs – negative velocity – Due to action of growth hormone.
      • Sex Differences – negative velocity is less in female .
      • At the age 8 year girl tens to have more fat than boy
    • 8 year to puberty – increase in fat level in both sexes
    • In infants body fat is called Brown Fat – have high metabolic rate → generate more heat. This is not seen in adult
  • Sex –
    • both girls & boys show reduction in fat till 8 yrs, the reduction is slower in girls
    • At puberty / adolescences
      • in Male reduction in truck & limb fat : temp halt
        • this loss of fat is gained back after 20.
      • in girl – increase in trunk fat – erotic figure.
  • Nutritional Level & Activity with Socio Economic dimension
    • Consumption of Fat diet
    • Low level of  activity
    • Industrial society
  • Ethnic Group –
    • High deposition o fat in things & buttocks, a condition c/l steatopygia which occur in Bushmen & Hottentots population.
      • As other population living in same environment doesn’t’ show ↠ Genetic control
    • Eskimos – high fat due to fatty diet, helps them to adjust to cold climate

Role of Adiposity in Blood Pressure Variation

  • Pattern of distribution of fat is more imp. than total amount of fat in BP,
  • Upper body fat more closely related to hyper tension than lower body fat.
  • Trunk fat more related to coronary heart disease than fat in extremities
  • Overweight in adulthood causes hypertension, cardiovascular disease, renal failure etc.
  • Nirmala et al – Andhra Pradesh study – centripetal fat or deep intra abdominal fat is more active cause of high blood pressure .

Studies

  • Hanna (1976) studies Amerindians had concluded that women are having higher temperature than children and males because of their higher fat content
  • Blair et al (1988) reported sub-cutaneous fat on trunk is riskier to coronaries than fat accumulated in extremities
  • Abraham (1971) Hypertension, heart disease and renal diseases are common for who are underweight in adulthood.

Respiratory Function

Introduction -Respiration is a process by which oxygen from the lungs is carried by blood to the tissues and carbon dioxide formed in the tissues by metabolic activity is carried by the lungs to be sent out. Respiratory Function are

  • Gas transfer – transfer of O2 to body parts and CO2 back to lungs.
  • Regulation of partial pressure of CO2 of Blood – this important function is to keep the arterial PCO2 at 40mm Hg which is essential for many vital functions of the body.

Function – These  are responsible for the exothermic, metabolic & oxidative activities of the lungs

Measurement – The total volume of air inside lungs is c/l Vital Capacity (4.5 liters), which is measured by Spirometer.

  • Age, sex & size of individual alter this vital capacity
  • Sex
    • Male = height(cm) X 20ml
    • Female = height (cm) X 16ml
  • Europeans have higher vital capacity
    • Males = height (cm) X 25ml
    • Female = height (cm) X 20ml
  • Old people have less vital capacity
  • People living in high attitude have to face the problem of low oxygen → develop (& also higher RBCs)

Variations – Variations in respiratory function exist at different levels

  1. Age Level – Older people witness respiratory issues due to efficiency of their respiratory functions.
  2. Gender – female have lower RBCs count & Hb level than males. Thus, they should have higher respiratory rate to compensate. But due to their lower metabolism & lung capacity, respiratory rate is lower in females than males.
  3. Environment – under hot conditions, rate of respiration declines. But it increases at colder & high altitude env.
  4. Occupation & commerce – stone cutters & construction workers have reduced respiratory capacity as dust particles block the lung pathways.
  5. Genetic Adaptations – e.g Tibetans have unique variants of EPASI Gene & EGLNI gene – two key genes in the oxygen homeostasis system. Thus their rate of respiration is stable even at high altitude.

Sensory Variations

Introduction – A person in made aware of his external environment by his sense organ. They are mainly 5 types of sense perception – touch, taste, smell, sight & sound. Among various sensory mechanisms most thoroughly surveyed are

PTC (Phenylthiocarbamide) Tasting Abilty

  • An autosomal polymorphic trait
  • Tasters – genotype TT & Tt
  • Non Taster -tt
  • Sex differences – female more sensitive to taste

Population variations in PCT tasting

  • Female more sensitive to PCT tasting – stastically signigicant differences
  • In Bakans, Burmese & Nigerian populations, female are more sensitive than male but difference si not statistically significant.
  • Muslims in India also don’t show sex differences in population for PCT tasting.

Red Green Colorblidness

  • Used as a gentic marker in human variations
  • X linked Trait
  • Individuals fail to distinguish red & green form each other

Studies Done for Red Green Colorblindness

  • India – In South India by Veera Raju, Rao & Reddy, Naidu, Shanti Devi etc
  • Outside India , Turkey – Bokesoy & Togan, in Balkans – Ibrahimov & Khnimov, Nigeria – Scott & in  Myanmar – Sint & maya

Population variations in Red Green Colorblindness –

  • Being an X linked disorder, it is more common among male than female populations
  • Prevalence of RG Colorblindness
    • Overall
      • Male 7-10 %
      • Female 0.5 -1 %
    • Caucasoid
      • Male 8 %
      • Female 0.64 %
    • Asian
      • Male 5 %
      • Female 0.25 %
    • AFricans
      • Male 4 %
      • Female 0.16 %

Thus, using these two markers, one can classify human population accordingly.

Other markers in sensor perception

  • Smell – female & children are known to hava a better sense of smell than males & adults respectively
  • Skin – female & children are. Perceived to be more sensitive to mechno-receptors.
    • Negroids are said to have a more heat – tolerant skin
    • While Caucasoid have a cold-tolerant skin.

Thus, sense perceptions are same in all human population with variations in the form and function with various cultural and socio-economic groups of people.