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. It is passed to the child only when both parents are unaffected carriers. The genes lie on an autosome, chromosome 16 for α-thalassemia and chromosome 11 for β-thalassemia.

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

(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.

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

(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) 2025 on 23-05-2025 (Slot 2) and on 20-05-2025 (Slot 1), and a similar question in CUET (UG) 2026 on 22-05-2026 (Slot 1).

NCERT Extract:
Mendelian Disorders – …