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Question:

Which of the following disorders are caused due to recessive autosomal mutations?

Edward's syndrome and Down's syndrome

Cystic fibrosis and phenylketonuria

Alzheimer's disease and Huntington's chorea.

Turner's syndrome and sickle cell anaemia

Solution:

Cystic fibrosis and phenylketonuria are caused by recessive autosomal mutations. Turner's syndrome is produced by the union of an abnormal O egg and a normal X sperm or a normal egg and an abnormal O sperm. The individual has 45 chromosomes (44 + X) instead of 46. Sickle cell anaemia is caused by a defective allele on chromosome 11. In homozygous condition, the disorder kills the individual. In heterozygous conditions, it leads to haemolytic anaemia under conditions of oxygen 60-70.