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Study the pedigree chart given below:
What does it show?
What does it show?
A
Inheritance of a recessive sex-linked disease like haemophilia
B
Inheritance of a sex-linked inborn error of metabolism like phenylketonuria
C
Inheritance of a condition like phenylketonuria as an autosomal recessive trait
D
The pedigree chart is wrong as this is not possible
Detailed Solution
In the chart, unaffected parents have affected children; this is possible only if the trait is recessive and both parents are heterozygous carriers.
The affected individuals include a female born to an unaffected father. For an X-linked recessive trait an affected daughter ($X^aX^a$) must have an affected father ($X^aY$), so sex-linked inheritance like haemophilia is ruled out.
The trait is therefore autosomal recessive: carrier parents $Aa \times Aa$ give affected children (aa) of either sex.
Phenylketonuria is an inborn error of metabolism inherited as an autosomal recessive trait (it is not sex-linked).
Hence the chart shows inheritance of a condition like phenylketonuria as an autosomal recessive trait.
The affected individuals include a female born to an unaffected father. For an X-linked recessive trait an affected daughter ($X^aX^a$) must have an affected father ($X^aY$), so sex-linked inheritance like haemophilia is ruled out.
The trait is therefore autosomal recessive: carrier parents $Aa \times Aa$ give affected children (aa) of either sex.
Phenylketonuria is an inborn error of metabolism inherited as an autosomal recessive trait (it is not sex-linked).
Hence the chart shows inheritance of a condition like phenylketonuria as an autosomal recessive trait.