Question

Identify the pattern of Inheritance

Answer 1

The pedigree shows inheritance of X-linked dominant disorder. The females are affected more than the males. The affected father passes his mutated X-chromosomes to his daughters and all of them show the disorder as the disorder is controlled by dominant gene. However, females of first generation are now heterozygous, so they may have 50% unaffected progeny when parried to an unaffected male. It is seen in the case of second female marrying to a normal male and the progeny is normal. However, the reverse is seen in the case of third female marrying to a normal male, where 50% of the progeny is affected. For example, Rett syndrome.