(Please show work so I can understand) Greg has two genetic disorders caused by

Question

(Please show work so I can understand)
Greg has two genetic disorders caused by mutations at a pair of linked genes on chromosome 13 that are 12cM apart. One of the disorders, alpha-disphoria, is an autosomal recessive disorder and the other, beta-disphoria, is an autosomal dominant disorder. Greg's father suffers from beta-disphoria (but not alpha-disphoria). Greg's mother has neither disorder. Greg marries Anna who has neither disorder. Greg and Anna have a daughter Jamie who have alpha-disphoria but not beta-disphoria.

A) If Greg and Anna have another child, what is the probability that the child has both genetic disorders?

Explanation / Answer

A) Genotype of Greg for having both alpha and beta dysphoria disorder (two mutany alleles - homozygous condition) is dd. Greg marries Anna with neither disorder (must be a healthy carrier ) and hence genotype of Anna is Dd. Greg's daughter Jamie has alpha dysphoria and hence heterozygous genotype dD. The probability of another child to have both disordres is = 1/2 x 1/2 = 1/4 = 0.25 or 25%.

B) The probability that the child has neither disorder = 1/2 x 1/2 x 1/2 x 1/2 = 1/8 = 0.125 or 12.5%

C) The probability that the child has neither disorder but is a carrier of alpha disphoria is = 1/2 = 0.5 or 50%.

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