The Mendelian disorder haemophilia is -

The correct answer is Option (2) → Sex linked recessive disease

A Mendelian disorder is caused by a change in a single gene. It can be dominant or recessive, and the gene can lie on an autosome or on a sex chromosome.

(1) Autosome linked recessive disease — Incorrect. Sickle-cell anaemia, cystic fibrosis and phenylketonuria are of this type. The gene for haemophilia is not on an autosome.

(2) Sex linked recessive disease — Correct. The gene for haemophilia lies on the X chromosome and is recessive. A carrier female, who is normal herself, can pass the disease to some of her sons. In the affected person, one protein of the blood clotting cascade is faulty, so even a small cut bleeds non-stop.

(3) Inborn error of metabolism — Incorrect. This term is used for diseases like phenylketonuria, in which an enzyme of metabolism is faulty. Haemophilia is a defect of a clotting protein.

(4) Autosomal linked dominant disease — Incorrect. Haemophilia is neither autosomal nor dominant.

NCERT Extract:
Mendelian Disorders – …