Thalassemia is:

The correct answer is Option (3) → Autosome-linked recessive disorder

Thalassemia is a blood disease in which the rate of making one of the globin chains of haemoglobin is reduced. This gives abnormal haemoglobin and anaemia. The genes lie on an autosome: chromosome 16 for α-thalassemia and chromosome 11 for β-thalassemia.

Option (1) Sex-linked recessive disorder — Incorrect. Haemophilia and colour blindness are of this type. Thalassemia is not carried on the sex chromosomes.

Option (2) Autosome-linked dominant disorder — Incorrect. Myotonic dystrophy is of this type, and a single copy of the gene is enough to show the trait. Thalassemia needs two copies.

Option (3) Autosome-linked recessive disorder — Correct. The gene is on an autosome and is recessive, as in sickle-cell anaemia and phenylketonuria.

Option (4) Sex-linked dominant disorder — Incorrect. NCERT lists no such Mendelian disorder, and thalassemia is not sex-linked.

Note: The same question was also asked in CUET (UG) 2026 on 31-05-2026 (Slot 2), and in CUET (UG) 2025 on 20-05-2025 (Slot 1), and a similar question in CUET (UG) 2026 on 22-05-2026 (Slot 1).

NCERT Extract:
Mendelian Disorders – …