Q107. A patient presents with features of right heart failure, horizontal nystagmus, and ataxia. There is no history of alcohol use or smoking. Which of the following deficiencies can cause this presentation?

Q108. A patient presents with features of dorsal column dysfunction such as ataxia and neuropathy. Laboratory tests show elevated total homocysteine and methylmalonic acid levels. Production of which of the following amino acids could be affected?

Q109. A child presents with elevated concentrations of phenylalanine. Phenylalanine hydroxylase activity is found to be normal. Which of the following coenzymes required for tyrosine metabolism could be deficient?

Q111. A boy presents with orange-colored tonsils and a family history of multiple cardiovascular-related deaths. Laboratory investigations show total cholesterol 80 mg/dL, triglycerides 146 mg/dL, HDL <5 mg/dL. Which of the following is the most likely diagnosis?

Q119. A labourer was stuck in a tunnel for 5 days. Which of the following functions as the primary source of energy for the brain during this period?

Q120. A 70-year-old man presents with a fracture following trivial trauma. He also has perifollicular hemorrhages, lusterless hair, and dry skin. He is on an exclusive diet of toast and buns and has microcytic hypochromic anemia. Which of the following enzymes is most likely affected in this patient?

Q121. A frameshift mutation was introduced into the coding sequence of an mRNA. If this occurs at the 4th position in an mRNA with 900 nucleotides, which of the following is most likely to happen?

Q123. A 10-year-old presents with multiple freckles and photosensitivity. Examination reveals two basal cell carcinomas on the face. Which of the following DNA repair mechanisms is defective?

Q124. A 10-year-old boy presents with coarse facial features, organomegaly, corneal opacity, and peripheral neuropathy. A deficiency of the enzyme alpha-L-iduronidase is found. Which of the following is accumulated in this condition?

Q125. A 7-month-old infant presents with developmental delay, seizures, and a cherry-red spot on fundoscopy. The mother has a history of abortion at 8 weeks. Genetic testing reveals a deficiency of hexosaminidase A. Which of the following accumulates in this condition?