A man with syndactyly, an autosomal-dominant condition, has one child who also has syndactyly. His unaffected wife states, "Because the risk for having a child withthis problem is 50% and our first child has the problem, the next child will not be affected." What is the best response to this statement?

Question

Quizplus · Accepted Answer

Many parents believe that the probability of transmitting an autosomal-dominant trait to their children is 50% for the total number of children, rather than for each pregnancy. Thus, the statement the mother made is incorrect. Having the first child express an autosomal-dominant health problem does not mean there is no risk for the second child also expressing it. Also, only the risk or probability is 50%. If they had three more children, it is possible that all three could have the problem, that all three could not have the problem, or that some may have it and not the other(s).

A Man with Syndactyly, an Autosomal-Dominant Condition, Has One Child