A Disease That is Lethal Only in the Homozygous Condition

Question

A disease that is lethal only in the homozygous condition is most likely which of the following?
A) autosomal recessive
B) autosomal dominant
C) X-linked
D) None of these choices are correct.

Accepted Answer

A disease that is lethal only in the homozygous condition is most likely due to an autosomal recessive gene. This is because in autosomal dominant inheritance, a single copy of the dominant allele would cause the disease, even in heterozygous individuals. X-linked inheritance would also be unlikely, as females would need two copies of the gene, which is unlikely due to the random X-inactivation process.