Imagine that you are searching for the gene associated with nail-patella syndrome, a dominant genetic disorder that causes developmental abnormalities. In a large pedigree you discover an association between nail-patella syndrome and a genetic marker that occurs in two different alleles, A and B. Fifteen individuals within this pedigree have nail-patella syndrome and are A/B heterozygotes for the marker. Thirty individuals within this pedigree don't suffer from nail-patella syndrome and are homozygous for the A marker allele. One individual within this pedigree has nail-patella syndrome and is also homozygous for the A marker allele. The most likely explanation for this exceptional individual is that ________.
A) a new mutation converted the disease-causing allele to the wild-type form
B) a new mutation converted the B allele of the marker to the A form
C) the exceptional nail-patella individual is haploid
D) recombination occurred between the nail-patella gene and marker locus in one of the parents of the exceptional individual

Question

Quizplus · Accepted Answer

The exceptional individual has nail-patella syndrome and is homozygous for the A marker allele, which is only found in individuals without nail-patella syndrome. This suggests a recombination event occurred between the nail-patella gene and the marker locus in one of the parents of the exceptional individual. This would result in the exceptional individual inheriting the A marker allele from both parents, but only inheriting the nail-patella disease-causing allele from one parent.

Imagine That You Are Searching for the Gene Associated with Nail-Patella