While doing a pedigree analysis of a royal family from a Pacific Island nation, you notice two parents with the same genetic disease who have four children. All four of the girls have the disease, but when they marry unaffected individuals, none of the 16 grandchildren has the disease. If this disease is controlled by a single gene, then the MOST likely explanation would be that the disease is:
A)a spontaneous mutation.
B)recessive and is only seen in homozygous recessive individuals such as the affected girls.
C)dominant and is only seen in homozygous dominant individuals.
D)dominant and is seen in heterozygous or homozygous dominant individuals.

Question

Quizplus · Accepted Answer

If all four of the daughters have the disease, it is likely that both parents carry a recessive gene for the disease. The fact that none of the grandchildren have the disease suggests that the daughters are carriers and their spouses do not carry the recessive gene. This would make the disease pattern consistent with a recessive inheritance.

While Doing a Pedigree Analysis of a Royal Family from a Pacific