Key differences, features, and comparative analysis of Disorder and Type.
| Disorder | Type | Key facts |
|---|---|---|
| Haemophilia | X-linked recessive | A clotting-factor protein not made → non-stop bleeding; mostly affects males; classic royal pedigree (Queen Victoria). |
| Sickle-cell anaemia | Autosomal recessive | Glutamic acid → Valine at 6th position of β-globin (GAG→GUG); HbˢHbˢ affected, HbᴬHbˢ carrier; RBCs sickle at low O₂. |
| Phenylketonuria | Autosomal recessive | Enzyme converting phenylalanine → tyrosine is absent; phenylalanine + derivatives accumulate → mental retardation; excreted in urine. |
| Thalassemia | Autosomal recessive | Reduced synthesis of globin chains (α on chr 16 / β on chr 11); a quantitative problem (too little globin). Contrast: sickle-cell is qualitative. |
| Colour blindness | X-linked recessive | Red-green defect; ~8% of males, ~0.4% of females. |
This comparison table is part of the chapter notes for Principles of Inheritance and Variation. Get complete notes, flashcards, active recall sheets, and test prep modes: