Chapter 5, Problem 28P

Neurofibromatosis $\text{1 }\left(\text{NF1}\right)$ is an autosomal dominant disorder inherited on human chromosome $\text{17}$. Part of the analysis mapping the $\text{NF1}$ gene to chromosome $\text{17}$ came from genetic linkage studies testing segregation of $\text{NF1}$ and $\text{DNA}$ genetic markers on various chromosomes. A $\text{DNA}$ marker with two alleles, designated $\text{1}$ and $\text{2}$, is linked to $\text{NF1}$. The pedigree below shows segregation of $\text{NF1}$(darkened symbols) and gives genotypes for the DNA marker for each family member.

a. Determine the alleles for the $\text{NF1}$ gene and the DNA marker gene on each chromosome carried by the fourfamily members in generation $\text{I}$ and generation $\text{II}$. UseN for the dominant $\text{NF1}$ allele and $\text{n}$ for the recessiveallele and assume $\text{I-1}$ is heterozygous for the diseaseallele ( $\text{Nn}$).

b. Based on the phase of alleles on chromosomes in generation $\text{II}$, is there any evidence of recombination amongthe eight offspring in generation $\text{III}$? Explain.

c. What is the estimated recombination frequency between the $\text{NF1}$ gene and the DNA marker?