Question

Incorrect statement with regard to haemophilia is

• A. A single protein involved in clotting of blood is affected
• B. It is sex-linked disease
• C. It is recessive disease
• D. It is a dominant disease

Answer 1

The Correct Option is D

To solve the question about the characteristics of haemophilia, let's analyze each given option to identify the incorrect statement related to haemophilia:

1. Option 1: A single protein involved in clotting of blood is affected
   • Haemophilia is a bleeding disorder where a specific protein necessary for blood clotting is either absent or deficient. In Haemophilia A, Factor VIII is affected, and in Haemophilia B, Factor IX is deficient.
   • This option correctly describes haemophilia as it affects specific proteins involved in the clotting process.
2. Option 2: It is sex-linked disease
   • Haemophilia is indeed a sex-linked disease. It is caused by mutations in genes located on the X chromosome.
   • This is because the genes that produce the clotting factors are located on the X chromosome, making it sex-linked.
3. Option 3: It is recessive disease
   • Haemophilia is a recessive disorder. For males (XY), one defective gene on the X chromosome will result in haemophilia since they have only one X chromosome.
   • Females (XX) would need two defective X chromosomes to manifest symptoms, which is why they are usually carriers.
4. Option 4: It is a dominant disease
   • This is incorrect. Haemophilia is not a dominant disease; it is a recessive disorder, as explained earlier.
   • A dominant disorder would mean a single defective gene in either male or female would display symptoms, which is not the case for haemophilia.

Based on the analysis above, the incorrect statement about haemophilia is, "It is a dominant disease." Hence, Option 4 is the correct answer to the question.