Revision summary
Rh groups centre on the D antigen. Positive means D present; negative means D absent. An Rh-negative mother can be sensitised by an Rh-positive fetus. Anti-D prophylaxis prevents most haemolytic disease. Frequencies differ by population, as a polymorphism.
Model answer
Introduction
The Rh blood-group system is a set of red-cell antigens, of which D is the clinically decisive one. It matters in transfusion and in pregnancy.
Body
Genetics and types
- Landsteiner and Wiener named Rhesus after the monkey work; later mapping showed a human RH locus on chromosome 1.
- Rh positive means D is present. Rh negative means D is absent. C, c, E, e add further types.
- Inheritance is Mendelian. Population frequencies vary: Rh-negatives are commoner in some European groups than in many Indian samples.
Medical anthropology
- An Rh-negative mother and Rh-positive fetus can cause haemolytic disease of the newborn after sensitisation.
- Anti-D immunoglobulin prevents most cases. Transfusion must still match D.
- It is a polymorphism, not a racial essence.
Flow diagram
flowchart TD RH[Rh system] --> D[Antigen D] D --> POS[Rh positive] D --> NEG[Rh negative HDN risk]
Conclusion
Rh is a red-cell system led by antigen D. Its anthropological use is population frequency; its medical use is transfusion and HDN prevention.
Quick related
Students also ask
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Is Rh the same as ABO?
No. They are different loci. Both must be matched in transfusion.
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Are all Indians Rh positive?
Most are D-positive, but Rh-negatives exist and need the same obstetric care.
PYQ trend
When UPSC asked this
Related PYQs from other years, newest first. Open a question to read it.
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2022 · Q8(a) · Anthropology GS 1 · 20 marks
Discuss the contemporary population problems in the light of various socio-cultural demographic theories -
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?
More from this topic
Q8(b) · UPSC Mains 2022 · 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?
Age, sex and population variation as genetic marker
A blood group system is a locus of cell-surface antigens. ABO and Rh are red-cell systems for transfusion. HLA is the MHC on leukocytes, used in graft matching. HLA polymorphism dwarfs ABO. Anthropology used both as population markers, not as races.
Q8(a) · UPSC Mains 2022 · Anthropology GS 1 · 20 marks
Discuss the contemporary population problems in the light of various socio-cultural demographic theories
Age, sex and population variation as genetic marker
Malthus and transition still frame public talk. Caldwell links fertility fall to reversed wealth flows and schooling. Boserup sees people as a force for agrarian intensification. Son preference and sex ratio are socio-cultural, as Sen showed. Ageing, migration, and slums are today’s problems, not a single explosion.
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