Question

PKU and albinism are two autosomal recessive disorders,unlinked in human beings. if couple each of them heterozygous for both traits, produce a child, what is the chance of their having a child with (a)PKU (b)albinism (c)both traits?

Answer 1

A. multiply the chance that it will be a boy x the chance he will have PKU (1/2 x 1/4)

B. chance of having PKU + chance of albinism

C. chance PKU x chance albinism

Answer 2

a) 3/16; b) 3/16; c) 1/16

Step-by-step explanation:

PKU and albinism are two autosomal recessive disorders. The possible genotypes and phenotypes for each disease are:

PKU

• PP: normal
• Pp: normal
• pp: PKU

Albinism

• AA: normal
• Aa: normal
• aa: albinism

If a couple of individuals heterozygous for both genes (PpAa) has offspring, from the Punnett Square we get the chances of them having:

a) PKU only

ppA_: 3/16

b) Albinism only

P_aa: 3/16

c) both traits

ppaa: 1/16