Question

Hillary is 8 years old and has neuronal ceroid lipofuscinosis, also known as Batten disease. It is autosomal recessive. She was fine until age five, when she began to lose her vision and stumble. She had learning difficulties in school and was diagnosed at age six. Hillary may only live into her twenties, experiencing dementia and seizures. Her younger brother Jaden, age six, is healthy, as are her parents. The probability that Jaden is a heterozygote is Group of answer choices

a.2/3.
b.1/4.
c.1/8.
d.1/3.

Answer 1

The probability that Jaden is a heterozygote (Bb) is 1/4 (option B).

Step-by-step explanation:

The probability that Jaden is a heterozygote is 1/4.

To determine the probability, we need to consider the parents' genotypes. Since Hillary has Batten disease, she must be homozygous recessive for the disease allele (bb). Her parents are unaffected, so they must be heterozygous carriers (Bb).

When Jaden is conceived, there is a 1/2 chance that he will inherit the disease allele from each parent. Therefore, the probability that Jaden is a heterozygote (Bb) is (1/2) * (1/2) = 1/4, option B is correct answer.