A disease caused by gene X is an autosomal dominant disease but is modified by expression of a gene on another chromosome gene Y.If gene Y has two recessive alleles,then the disease is mild.If there is a dominant allele present for gene Y,then the disease is aggressive.What are the chances the child will have the aggressive form of the disease?

Question

Quizplus · Accepted Answer

For the child to have the aggressive form of the disease, they must inherit the dominant allele for gene X (since the disease is autosomal dominant) and at least one dominant allele for gene Y (since the presence of a dominant allele for gene Y makes the disease aggressive). Assuming each parent is heterozygous for both genes (XxYy), the chance of inheriting the dominant allele for gene X is 3/4 (XX or Xx), and the chance of inheriting at least one dominant allele for gene Y is also 3/4 (YY or Yy). Multiplying these probabilities gives 3/4 * 3/4 = 9/16.

A Disease Caused by Gene X Is an Autosomal Dominant