Question

Study the pedigree chart given below :
What does it show ?

• A. Inheritance of a recessive sex - linked disease like haemophilia
• B. Inheritance of a sex-linked inborn errow 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

Answer 1

The correct option is C Inheritance of a condition like phenylketonuria as an autosomal recessive trait

A pedigree is a chart of the genetic history of a family over several generations. Males are represented as squares, while females are represented as circles. Shaded symbols mean an individual is affected by a condition, while an unshaded symbol means they are unaffected. If both parents are unaffected and an offspring is affected, the trait must be recessive (parents are heterozygous carriers). If neither of a PKU child's parents has the disorder themselves that means they have two recessive genes for the disorder. So this chart represents - the inheritance of a condition like phenylketonuria as an autosomal recessive trait.