Primary generalized osteoarthritis PGO is a sexinfluenced tr

Primary generalized osteoarthritis (PGO) is a sex-influenced trait. It is the result of an allele on an autosome that is dominant in females and recessive in males. An affected man marries an affected woman who had an unaffected mother. What is the probability that a son would be affected?

  Primary generalized osteoarthritis (PGO) is a sex-influenced trait. It is the result of an allele on an autosome that is dominant in females and recessive in males. An affected man marries an affected woman who had an unaffected mother.
What is the probability that a daughter would be affected?

Solution

In Autosomal dominant inheritance, the offspring are affected when one or both parents are affected. In some dominant traits the heterozygote exhibits incomplete penetration due to which the affected offspring may not exhibit the trait. The affected offspring may also produced by occurring a dominant mutation during the gametogenesis. When one of the parents is affected, the progeny produced will be 50% affected and when both parents are affected the chance of unaffected offspring would be 25%. The trait is a dominant and expressed in the same frequency in both males and females. The Autosomal dominant traits mainly exhibited due to haploinsufficiency, a gain – of – function mutation or a dominant – negative mutation.

Autosomal dominant allele of PGO in females = PP

Autosomal recessive allele of PGO in males = pp

PP X pp

The offspring produced from above cross are heterozygotes and exhibit incomplete penetrance due to which, the affected offspring do not exhibit the trait. The probability of affected son and daughter are 50%.