Question

Which of the following is true regarding ataxia telangiectasia?

• A. Increase in AFP (alpha-fetoprotein)
• B. Increases the risk of squamous cell carcinoma
• C. Autosomal dominant
• D. None of the above

Hint:

ATM gene defect, autosomal recessive, lymphoid cancers, and a hallmark raised serum AFP.

Answer 1

The Correct Option is A

Step 1: Ataxia-telangiectasia (Louis-Bar syndrome) is a rare autosomal recessive neurodegenerative disorder caused by mutation of the ATM gene, which normally senses and helps repair DNA double-strand breaks. The triad is progressive cerebellar ataxia, oculocutaneous telangiectasias, and immunodeficiency with recurrent sinopulmonary infections.
Step 2: A characteristic and clinically useful laboratory finding is a persistently raised serum alpha-fetoprotein (AFP). Elevated AFP is one of the most consistent markers of the disease, which makes option (a) correct.
Step 3: The distractors are wrong. Inheritance is autosomal recessive, not dominant, so (c) fails. Because DNA repair is defective and there is radiation sensitivity, the cancer risk is dominated by lymphoid malignancies - lymphoma and leukaemia - rather than squamous cell carcinoma, so (b) fails. Since a true statement exists, "none of the above" (d) cannot be chosen.