Both parents are heterozygous for Tay-Sachs disease (an autosomal recessive disorder). Three children in a row were born with Tay-Sachs disease. What is the chance that a fourth child will have Tay-Sachs disease?
A) 25%
B) 0%
C) 50%
D) 75%
E) 100%

Question

Quizplus · Accepted Answer

The chance that a child will inherit Tay-Sachs disease when both parents are heterozygous is 25% for each pregnancy, independent of previous outcomes.

Both Parents Are Heterozygous for Tay-Sachs Disease (An Autosomal Recessive