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

question 37

Multiple Choice

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 _____.

• 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 gene in one of the parents of the exceptional individual