Question

Read the passage and answer the following question

Hemophilia is a genetic disorder caused by an X-linked recessive allele. It is of historical interest because of the extensive familial intermarriages of the royal houses of Europe during the seventeenth to nineteenth centuries AD.

This lethal allele continued to be passed on

• A. Because of the founder effect
• B. Because, while producing a bleeding disorder, it increases longivity
• C. Because it only affects female carriers of the trait
• D. Because the recessive allele provides a selection advantage
• E. Because of disruptive selection

Answer 1

The correct option is A Because of the founder effect

Founder effect refers to genetic drift i.e. reduced genetic diversity resulting from a small population colonizing a new area. This resulted in the presence of a small fraction of genetic diversity in the founder population as compared to the original population and allowed the lethal allele to survive. Hemophilia can cause death of the affected person and does not impart longevity or any other survival advantage. Female carriers exhibit normal phenotype while only hemizygous recessive males and homozygous recessive females exhibit the disease. Thus, the correct answer is option A.