Which of the following are autosomal recessive trait/ disorder?(A) Th…

The correct answer is Option (2) → (A), (C) and (D) only

An autosomal recessive disorder is caused by a gene on an autosome (not on a sex chromosome). It shows only when both alleles are defective; carriers with one defective allele are normal.

(A) Thalassemia — Autosomal recessive. It is an autosome-linked recessive blood disease, passed on when both parents are carriers.

(B) Haemophilia — Not autosomal. Its gene is on the X chromosome, so it is a sex-linked recessive disorder, seen mostly in males.

(C) Sickle cell anaemia — Autosomal recessive. It shows only in persons homozygous for the allele Hb^S.

(D) Phenylketonuria — Autosomal recessive. It is an inborn error of metabolism inherited as an autosomal recessive trait.

Note: A similar question was also asked in CUET (UG) 2025 on 14-05-2025 (Slot 1).

NCERT Extract:
Mendelian Disorders – “… Haemophilia : This sex linked recessive disease, which shows its transmission from unaffected carrier female to some of the male progeny has been widely studied.”
Mendelian Disorders – “… Sickle-cell anaemia : This is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous).”
Mendelian Disorders – “Phenylketonuria : This inborn error of metabolism is also inherited as the autosomal recessive trait.”
Mendelian Disorders – “Thalassemia : This is also an autosome-linked recessive blood disease transmitted from parents to the offspring when both the partners are unaffected carrier for the gene (or heterozygous).”