Question

One of the genetic disorders affecting central nervous system is Tay-Sachs disease. The disease is lethal for homozygous recessive individuals at an early age. Such a fatal disease can be carried in a population

• A. If one parent is heterozygous, the offspring have a 25% chance of being heterozygouos.
• B. If If one parent is heterozygous, the offspring have a 75% chance of being heterozygouos.
• C. If one parent is heterozygous, the offspring have a 100% chance of being heterozygouos.
• D. If one parent is heterozygous, the offspring will be carriers.
• E. If one parent is heterozygous, the offspring have a 50% chance of being heterozygouos.

Answer 1

The correct option is E If one parent is heterozygous, the offspring have a 50% chance of being heterozygouos.

The recessive alleles of fatal diseases are maintained in the gene pool by heterozygous carrier individuals. A cross between heterozygous dominant and homozygous dominant produce progeny in 1 homozygous dominant: 1 heterozygous dominant genotypic ratio. So, there are 50% chances of the progeny to be a heterozygous carrier. The correct answer is E.