This pedigree shows a family with TaySachs disease which is

This pedigree shows a family with Tay-Sachs disease which is inherited in an autosomal recessive manner. Members of the family with filled symbols have Tay-Sachs. Which members of this family are definitely heterozygous (Tt)? 1-1, 1-2, II-2, II-3, and III -1 1-1, 1-2, II-2, and II-3 only 1-1, 1-2, and II-3 only I-1 and I-2 and only

Solution

Answer:

D). I-1 and I-2 and only

I-1 & I-2 are definitely are heterozygous

II-2, II-3 & III-1 are may or may not heterozygous