CBSE BIOCHEM Exam With Complete Questions And Answers Graded A

Lesch-Nyhan Syndrome: what causes it and what are manifestations? Correct Answer: HGPRT deficiency in purine salvage pathway (this enzyme normally converts hypoxanthine to IMP and guanine to GMP). This deficiency leads to excessive Uric acid production and de novo purine synthesis. It is X linked recessive. Symptoms: hyperuricemia, gout, aggression / self mutilation, mental retardation, dystonia. Treatment for Lesch-Nyhan? Correct Answer: Allopurinol / febuxostat second line. Both of these drugs inhibit xanthine oxidase, which converts hypoxanthine to xanthine and xanthine to uric acid. Adenosine Deaminase Deficiency: what is it, what effects does it have? Correct Answer: ADA is required for degradation of adenosine and deoxyadenosine--dATP builds up and is toxic to lymphocytes, which is why this disease is a major cause of SCID--severe combined immunodeficiency (Autosomal recessive)