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: Understanding the Concept:
Genetic disorders are classified based on their inheritance patterns. An autosomal recessive disorder requires an individual to inherit two copies of the mutated gene (one from each parent) to express the disease. We need to identify which of the listed diseases follow this pattern.
Step 2: Detailed Explanation:
Let's determine the inheritance pattern for each disorder:


A. Huntington disease: This is a classic example of an autosomal dominant disorder. An individual needs to inherit only one copy of the mutated gene to develop the disease.

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

C. Lesch-Nyhan syndrome: This is an X-linked recessive disorder. It is caused by a mutation on the X chromosome and therefore primarily affects males. It is not autosomal.

D. Tay-Sachs disease: This is a lysosomal storage disorder that follows an autosomal recessive inheritance pattern. An individual must inherit two copies of the defective gene for the HEXA enzyme to have the disease.

Step 3: Final Answer:
The autosomal recessive disorders on the list are Sickle cell anemia (B) and Tay-Sachs disease (D).