Chapter 11, Problem 27P

The microarray shown in Problem 25 analyzes genomic DNA from a nuclear family in which the father, one son, and one daughter have rare, late onset polycystic kidney disease; while the mother, the second son, and the second daughter are unaffected. As stated in Problem 25, the eight SNP loci examined are evenly spaced at about 10 Mb intervals on chromosome 4, and they are shown on the microarray in their actual order on this chromosome.

a.	Is the allele responsible for the disease dominant or recessive with respect to wild type? Is the disease gene autosomal or X-linked?
b.	For each of the four siblings, indicate the genotype of the sperm from which they were created. For each of these sperm, write the alleles for each of the eight loci on chromosome 4 in order.
c.	Identify the two SNP loci that are uninformative in this family (that is, you cannot determine whether or not either of these loci is linked to the disease gene).
d.	Assuming for the sake of simplicity that the four children shown would be completely representative even if the parents had 100 children, the data in the figure indicate that one locus is unlinked to the disease gene. Which one?
e.	The microarray results indicate that during meiosis in the father, two different crossovers occurred in the region including the disease gene and the SNP loci that are genetically linked to it. Draw a map of chromosome 4 showing the locations of the disease gene, the linked SNP loci, and the two crossovers. Your map should indicate any uncertainties in these positions.
f.	Diagram the location and arrangement (phase) of all alleles of all genes that are on the two chromosomes in the father’s diploid genome.