A 24-year-old woman of Ashkenazi Jewish descent presents with recurrent bloody diarrhea and abdominal pain. She says she feels well otherwise. Review of systems is significant for a 4 kg weight loss over the past month. Physical examination is significant for multiple aphthous oral ulcers. Colonoscopy reveals a cobblestone pattern of lesions of the mucosa of the intestinal wall with skip lesions involving the terminal ileum and colon. The patient is informed of the diagnosis and medication to treat her condition is prescribed. On a follow-up visit 6 weeks later, the patient presents with non-productive cough, chest pain, dyspnea on exertion, and worsening oral lesions. A chest radiograph reveals a diffuse interstitial pattern. Which of the following enzymes is inhibited by the medication most likely prescribed for her initial diagnosis?
AThymidine kinase
BDNA polymerase
CDihydrofolate reductase
DHypoxanthine guanine-phosphoribosyltransferase (HGPRT)
EThymidylate synthase
A 3-month-old boy is brought to the pediatrician by his mother after she notices orange sand–like crystalline material in her child’s diaper. He is not currently taking any medication and is exclusively breastfed. His immunizations are up to date. The doctor tells the mother that her son may have an X-linked recessive disorder. The boy is prescribed a medication that inhibits an enzyme responsible for the production of the crystals seen in his urine microscopy. Which of the following enzymes is the target of this medication?
AAdenosine deaminase
BXanthine oxidase
CAdenine phosphoribosyltransferase
DHypoxanthine-guanine phosphoribosyltransferase
EAminolevulinic acid synthetase
A 54-year-old woman presents with acute pain in her left toe. She says she hasn't been able to wear closed shoes for 2 weeks. Past medical history is significant for gastroesophageal reflux disease, diagnosed 2 years ago. The patient is afebrile and vital signs are within normal limits. Her BMI is 31 kg/m2. On physical examination, the left toe is warm to touch, swollen, and erythematous. A joint fluid aspiration from the left toe is performed and shows needle-shaped negatively birefringent urate crystals. The patient is started on methotrexate for gout prophylaxis. On her follow-up visit 6 weeks later, she has an elevated homocysteine level, a decreased serum folic acid level, and a normal methylmalonic acid level. Which of the following drugs would most likely cause a similar side effect to that seen in this patient?
ACisplatin
Bα-Methyldopa
CCephalosporins
DPenicillins
EAzathioprine
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