Pedigree / Allele Identification Huntington's Problem

. The dominant allele for Huntington disease is segregating in the pedigree shown below. Also shown is the pattern of DNA bands observed for a restriction fragment polymorphism. Interpret the banding pattern to be the phenotype of a codominant gene. The bands are designated by the numbers 1 and 2. Use HD and hd for the Huntington alleles, and A1 and A2 for the restriction fragment alleles that yield bands 1 and 2, respectively.

a. Deduce the genotype of each person in the pedigree with respect to the Huntington gene and the restriction fragment polymorphism locus.

b. Suggest a reason why no persons are observed who have only the smaller DNA fragment (fragment 2, the lower band).

c. The two genes are linked. List each person who carries a recombinant chromosome according to the numbers across the bottom of the gel.

d. Estimate the RF between the Huntington gene and the restriction fragment gene. Do not include persons 4, 14, 19, 20 or 27 in your calculations.

Using this photo: