Question:medium
Consider the following diseases:
1. Huntington's disease
2. Cystic fibrosis
3. Sickle Cell anaemia
4. Haemophilia A
Which of the following disorders are transmitted as autosomal recessive genetic disorders?
Consider the following diseases:
1. Huntington's disease
2. Cystic fibrosis
3. Sickle Cell anaemia
4. Haemophilia A
Which of the following disorders are transmitted as autosomal recessive genetic disorders?
1. Huntington's disease
2. Cystic fibrosis
3. Sickle Cell anaemia
4. Haemophilia A
Which of the following disorders are transmitted as autosomal recessive genetic disorders?
Show Hint
Recall which of these four diseases need two faulty gene copies on an autosome.
Updated On: Jul 7, 2026
- 1, 2 and 4
- 1 and 2
- 2 and 3
- 3 and 4
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: What the question is testing.
This question checks if you know the inheritance pattern of four common genetic diseases: Huntington's disease, Cystic fibrosis, Sickle Cell anaemia and Haemophilia A.
Step 2: The rule for autosomal recessive disease.
A disease is autosomal recessive when its gene sits on a normal numbered chromosome (not X or Y) and a person needs both copies of that gene faulty to actually get sick. One faulty copy alone is not enough.
Step 3: Go disease by disease.
Huntington's disease only needs one bad copy of the gene on chromosome 4, so it is dominant, not recessive.
Cystic fibrosis needs two bad copies of the CFTR gene on chromosome 7, so it is recessive and it is on an autosome.
Sickle Cell anaemia needs two bad copies of the beta globin gene on chromosome 11, so it is also autosomal recessive.
Haemophilia A comes from a bad gene on the X chromosome, so it is X linked, not autosomal, even though it behaves in a recessive way.
Step 4: Pick the pair.
Only Cystic fibrosis and Sickle Cell anaemia, numbers 2 and 3, satisfy both conditions: recessive and autosomal.
Step 5: Answer.
$\text{2 and 3, Cystic fibrosis and Sickle Cell anaemia}$ is correct.
\[ \boxed{\text{2 and 3}} \]
This question checks if you know the inheritance pattern of four common genetic diseases: Huntington's disease, Cystic fibrosis, Sickle Cell anaemia and Haemophilia A.
Step 2: The rule for autosomal recessive disease.
A disease is autosomal recessive when its gene sits on a normal numbered chromosome (not X or Y) and a person needs both copies of that gene faulty to actually get sick. One faulty copy alone is not enough.
Step 3: Go disease by disease.
Huntington's disease only needs one bad copy of the gene on chromosome 4, so it is dominant, not recessive.
Cystic fibrosis needs two bad copies of the CFTR gene on chromosome 7, so it is recessive and it is on an autosome.
Sickle Cell anaemia needs two bad copies of the beta globin gene on chromosome 11, so it is also autosomal recessive.
Haemophilia A comes from a bad gene on the X chromosome, so it is X linked, not autosomal, even though it behaves in a recessive way.
Step 4: Pick the pair.
Only Cystic fibrosis and Sickle Cell anaemia, numbers 2 and 3, satisfy both conditions: recessive and autosomal.
Step 5: Answer.
$\text{2 and 3, Cystic fibrosis and Sickle Cell anaemia}$ is correct.
\[ \boxed{\text{2 and 3}} \]
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