Chapter 11, Problem 31P

The pedigree shown in Fig. 11.22 was crucial to the identification of the Huntington disease gene HD, which is located on chromosome 4.

 

a.	The data show that the DNA marker G8 is clearly linked to HD. For the large majority of the people in the pedigree with Huntington disease, which allele of G8 (A, B, C, or D) did they inherit, along with the dominant disease-causing allele of HD, on the copy of chromosome 4 from their affected parent?
b.	How many people in the pedigree can you categorize absolutely as the product of parental or recombinant gametes from their affected parent, without making any assumptions at all (including the assumption of linkage)?
c.	If you now make the assumption that G8 and HD are linked, how many of the people in this pedigree must be the product of a recombinant gamete from their affected parent?
d.	Based solely on the data from this pedigree, what would be the best estimate for the map distance between G8 and HD?
e.	Considering your answers to parts (b) through (d), calculate the maximum Lod score. The pedigree contains 47 people resulting from informative matings. (Note that 00 = 1.) What does this Lod score signify?