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Pick out the correct statements. I. Haemophilia is a sex-linked recessive disease. II. Down's syndrome is due to aneuploidy. III. Phenylketonuria is an autosomal recessive gene disorder. IV. Sickle cell anaemia is an X-linked recessive gene disorder.
A
II and IV are correct.
B
I, III and IV are correct.
C
I, II and III are correct.
D
I and IV are correct.
Explanation
Sickle-cell anaemia is autosomal, not X-linked.
Detailed Solution
Sickle-cell anaemia is an autosomal recessive disorder caused by a point mutation replacing glutamic acid with valine in the haemoglobin β-chain, forming abnormal haemoglobin. So statement IV is wrong; the remaining three statements are correct.