Revision summary
Immunogenetics studies genes of antigens and immune response. ABO and Rh govern transfusion and newborn haemolysis. HLA matching is central to transplantation. HLA alleles associate with autoimmune disease. Population HLA maps are anthropological, not racial medicine.
Model answer
Copper italics in this answer — like this — are the key facts. Each one is unpacked in the Facts & figures rail.
Introduction
Immunogenetics is the genetics of the immune system. It studies inherited variation in antigens, antibodies, and the loci that decide transplant and disease risk.
Body
Core
- Blood-group antigens are immune structures: ABO and Rh decide transfusion and haemolytic disease of the newborn.
- HLA (MHC) on chromosome 6 is the densest human immunogenetic map. Matching matters in kidney and bone-marrow grafts.
- Antibody allotypes (Gm, Km) and immunoglobulin gene rearrangements join Mendelian inheritance to somatic diversity.
Examples
- Landsteiner found ABO. Levine linked Rh to newborn jaundice.
- Ankylosing spondylitis and HLA-B27, coeliac and HLA-DQ, type 1 diabetes and DR/DQ haplotypes.
- G6PD and some complement loci sit on the border of immuno-haematology and infection.
- Hybridoma and now sequencing of TCR and BCR repertoires are laboratory immunogenetics.
Anthropology
- HLA clines and Indian caste-tribe samples are used in population history, with care against racial medical myths.
Flow diagram
flowchart TD IG[Immunogenetics] --> ABO[ABO Rh transfusion] IG --> HLA[MHC transplant disease] IG --> AB[Antibody allotypes]
Conclusion
Immunogenetics is inherited immune variation. ABO, Rh, and HLA are the teaching trio, with disease associations and transplant matching as the applied face.
Quick related
Students also ask
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Is every immune trait Mendelian?
Germline HLA and ABO are. Antibody specificity also uses somatic recombination.
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Why does anthropology teach HLA?
It is both clinical matching and a highly polymorphic record of population history.
Same topic · past papers
UPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.
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2026 · Q7(b) · Anthropology GS 1 · 15 marks
What do you understand by fertility and mortality? How are these influenced by biological and socio-ecological factors? -
2025 · Q2(b) · Anthropology GS 1 · 15 marks
Compare and contrast the symbolic approaches of Clifford Geertz and Victor Turner to understand culture -
2022 · Q8(b) · Anthropology GS 1 · 15 marks
What do you understand by blood group systems? How is HLA system different from those based on red cell antigens? -
2026 · Q3(a) · Anthropology GS 1 · 20 marks
How do the concepts of power, authority, legitimacy and social control change with changing political organization? Discuss in detail giving suitable examples -
2026 · Q3(c) · Anthropology GS 1 · 15 marks
Numerical chromosomal aberrations can be due to abnormalities in autosomes as well as sex chromosomes. Elaborate in terms of the effects these have on human body, giving suitable examples
More from this topic
Q1(a) · UPSC Mains 2025 · Anthropology GS 1 · 10 marks · Solution
Mendelian and non-Mendelian traits.
Mendelian genetics in man-family study, single factor, multifactor, lethal, sub-lethal and polygenic inheritance in man.
Mendelian traits follow one-locus segregation and can be read in a pedigree. ABO, PTC tasting, albinism, haemophilia A and Huntington disease are standard examples. Multiple alleles and sex-linkage extend Mendelism; they do not cancel it. Non-Mendelian traits include polygenic stature and skin colour, linkage, maternal mtDNA and imprinting. Environment plus many genes gives a curve, not a 3:1 ratio. Use family study for Mendelian markers and quantitative genetics for everyday variation. Single-factor, multifactor, lethal and polygenic inheritance is this same distinction.
Q8(b) · UPSC Mains 2024 · Anthropology GS 1 · 15 marks · Solution
Describe the genetics and inheritance patterns of the ABO and Rh blood groups in man.
Mendelian genetics in man-family study, single factor, multifactor, lethal, sub-lethal and polygenic inheritance in man.
ABO lies on chromosome 9 and encodes glycosyltransferases acting on H antigen. Iᴬ and Iᴮ are codominant; both dominate common O. Bombay phenotype hh lacks H antigen and demonstrates epistasis. Rh is a chromosome-1 complex centred on RHD and RHCE, not literally one allele pair. Maternal IgG anti-D can cause haemolytic disease after sensitisation; prophylaxis prevents most cases. Blood-group frequencies trace populations but cannot define races or prove unique paternity.
Q7(b) · UPSC Mains 2024 · Anthropology GS 1 · 15 marks · Solution
What is a multifactorial trait? Illustrate your answer with suitable human examples.
Mendelian genetics in man-family study, single factor, multifactor, lethal, sub-lethal and polygenic inheritance in man.
A multifactorial trait combines many genetic variants with environment and development. Fisher explained continuous variation through many small Mendelian effects. Height, pigmentation, BMI and blood pressure are continuous examples. Cleft lip, neural-tube defects, diabetes and hypertension can use a liability-threshold model. Twin, family and GWAS designs estimate components but depend on population and environment. Yajnik's thin-fat phenotype illustrates developmental and nutritional interaction in India.