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

question 51

Multiple Choice

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) 0%
• B) 25%
• C) 50%
• D) 75%
• E) 100%

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Definitions:

External Ear

The outer portion of the ear, consisting of the pinna and the ear canal, which gathers sound waves and directs them inward.

Cerumen

A natural, waxy substance produced by glands in the ear canal that helps protect and lubricate the ear.

Toxoplasmosis

An infection caused by the Toxoplasma gondii parasite, often contracted from cats or contaminated food.

Rubella

A contagious viral infection best known by its distinctive red rash, also called German measles, and potentially dangerous to pregnant women due to its teratogenic effects.