Identify the autosome-linked recessive disorder.

The correct answer is Option (3) → Thalassemia

Option (1) Myotonic dystrophy — Incorrect. It is an autosomal disorder, but a dominant one: one copy of the defective allele is enough to cause it.

Option (2) Color blindness — Incorrect. It is a recessive disorder, but sex-linked: the gene is on the X chromosome. It causes a defect in the red or green cone of the eye and is far more common in males.

Option (3) Thalassemia — Correct. The gene is on an autosome, and a child is affected only when both parents pass on the defective allele. Too few globin chains are made, so the haemoglobin is abnormal and the person becomes anaemic. In α thalassemia the genes are on chromosome 16; in β thalassemia the gene is on chromosome 11.

Option (4) Haemophilia — Incorrect. Haemophilia is also sex-linked recessive. A protein of the blood-clotting chain is missing, so even a small cut keeps bleeding.

NCERT Extract:
Mendelian Disorders – …