Question

Which of the following are autosomal recessive genetic disorder?
A. Huntington disease
B. Sickle cell anemia
C. Lesch-Nyhan syndrome
D. Tay-Sachs disease
Choose the correct answer from the options given below:

• A. B and D only
• B. A, B and C only
• C. A, B, C and D
• D. B, C and D only

Hint:

For genetics questions, it's crucial to memorize the inheritance patterns of benchmark diseases. \textbf{Huntington's = Autosomal Dominant}. \textbf{Cystic Fibrosis, PKU, Sickle Cell, Tay-Sachs = Autosomal Recessive}. \textbf{Duchenne Muscular Dystrophy, Hemophilia, Lesch-Nyhan = X-linked Recessive}.

Answer 1

The Correct Option is A

Step 1: Concept Overview:
Genetic disorders are categorized by how they are inherited. Autosomal recessive disorders require inheriting two copies of a mutated gene (one from each parent) for the disease to manifest. We must identify the autosomal recessive diseases from the list.
Step 2: Detailed Analysis:
Let's examine the inheritance pattern of each disorder:


A. Huntington disease: This is an autosomal dominant disorder. Only one copy of the mutated gene is needed for disease development.

B. Sickle cell anemia: This is an autosomal recessive disorder. Individuals must be homozygous for the sickle cell allele (HbS/HbS) to exhibit the disease. Heterozygotes (HbA/HbS) have the sickle cell trait but are typically asymptomatic.

C. Lesch-Nyhan syndrome: This is an X-linked recessive disorder. It's caused by a mutation on the X chromosome, predominantly affecting males, and is not autosomal.

D. Tay-Sachs disease: This is a lysosomal storage disorder with an autosomal recessive inheritance. Two copies of the defective HEXA gene are required to develop the disease.

Step 3: Conclusion:
The autosomal recessive disorders listed are Sickle cell anemia (B) and Tay-Sachs disease (D).