The reasoning: community genetics
| Condition | Inheritance | India |
|---|---|---|
| Sickle cell disease | Autosomal recessive (HbS) | High trait prevalence (up to 10–40% in some tribal communities) in central, western and southern India |
| β‑thalassaemia | Autosomal recessive | Carrier ≈ 3–4% overall; higher in Sindhi, Punjabi, Gujarati, Bengali, Parsi communities; ≈ 10,000–15,000 thalassaemia major births/year |
| G6PD deficiency | X‑linked | Relevant to primaquine (Concept 75) |
| Congenital hypothyroidism | Mostly sporadic | ≈ 1 in 1,000–2,500 births; newborn screening (TSH) |
| Down syndrome | Chromosomal (trisomy 21) | Risk rises with maternal age |
| Consanguinity | Increases autosomal recessive disorders | Common in parts of south India |