(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?
B) What is the probability that the child has neither disorder?
C) What is the probability that the child has neither disorder but is a carrier of alpha-disphoria?

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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