Question

Sol.(c) [Key Concept: Sex-Linked Disorders — Haemophilia] HAEMOPHILIA is a sex-linked (X-linked recessive) disorder. The haemophilia A gene (Factor VIII) and haemophilia B gene (Factor IX) are both located on the X chromosome. Males with one mutant X allele (X^h Y) express haemophilia; females need both X chromosomes affected (X^h X^h) to show the disease. Sickle cell anaemia, albinism, and phenylketonuria are all AUTOSOMAL recessive disorders (not sex-linked).