Question

The pedigree chart represents

• A. X linked recessive trait
• B. autosomal recessive trait
• C. autosomal dominant trait
• D. Y linked trait

Answer 1

The correct option is B autosomal recessive trait

The given pedigree chart represents autosomal recessive trait. Autosomal recessive trait is the type of trait which is present on autosomes (chromosomes other than the sex chromosomes) and are only expressed when both the alleles of the trait are present.

The I generation male and female are heterozygous or carriers and hence, unaffected. But the recessive alleles were transmitted to their offspring. If the trait is autosomal dominant, the parents (individuals) in heterozygous conditions will be affected which has not happened in this case. So, the pedigree chart represents an autosomal recessive trait.

Pedigree chart cannot be X linked disorder because the parents of the affected females in the II generation are unaffected. For X linked recessive trait, the father should be affected and the mother should be a carrier or be affected for the trait to pass to their offspring.

Pedigree chart cannot be Y linked disorder as the Y linked disorder transmits in only males which is not happening in this case.