Lysosome

(M1.BC.17.4799) An 18-month-old girl is brought to the pediatrician’s office for failure to thrive and developmental delay. The patient’s mother says she has not started speaking and is just now starting to pull herself up to standing position. Furthermore, her movement appears to be restricted. Physical examination reveals coarse facial features and restricted joint mobility. Laboratory studies show increased plasma levels of several enzymes. Which of the following is the underlying biochemical defect in this patient?

(M1.BC.15.74) A 25-year-old male presents to his dermatologist for the appearance of small red papules on his buttocks as seen in Figure A. A careful history reveals that the male has had pain in his extremities for the past several years and recently he is experiencing a constant burning sensation in his extremities. Furthermore, he notes that he occasionally gets fevers when the pain is severe. A blood sample was taken and sent for analysis. Results revealed an alpha-galactosidase A activity of 1.5 nmol/hr*mg (nl = 25-55 nmol/hr*mg). Which of the following is most likely accumulated in the lysosomes of this individual?

(M1.BC.15.0) A 1-year-old Israeli child is brought to the pediatrician by his parents because they noticed that the child can no longer sit up, hold his head up, or recognize them anymore. The child's height and weight are in the 25th percentile for his age. On physical exam, the pediatrician notes the child has hepatosplenomegaly and the following is seen on ophthalmoscopic exam (Figure A). A bone marrow biopsy was performed, and the results shown in Figure B. Which of the following is deficient in this male child?

(M1.BC.15.17) A 6-year-old Hispanic male was admitted to the hospital for pain in his left thigh that has increased in severity over the past several months to the point that he can no longer walk. His mother explained that he had the pain about a year ago that resolved spontaneously. She also explained that he has had nose bleeds frequently for the past 6 months. On physical exam, hepatosplenomegaly was observed and he was noted to have a low-grade fever. A CT with intravenous contrast demonstrated aseptic necrosis of the left femoral head. Based on the clinical presentation, the attending physician ordered an assay showing significantly low levels of beta-glucocerebrosidase in peripheral blood leukocytes. Which of the following diseases shares a similar mode of inheritance as the disease experienced by this patient?

(M1.BC.15.27) An autopsy was performed on a 2-year-old male child. The clinical report stated that the child's parents were first cousins, and that he had deteriorated physically and mentally over the past year, becoming deaf, unable to eat, and paralyzed. A brain biopsy demonstrated the accumulation of GM2-gangliosides in the neurons. Which of the following enzymes was missing from this child?

(M1.BC.14.27) A mother brings her 1-year-old daughter who has had several seizures in the past 2 weeks to the pediatrician. The mother explains that the child is unable to crawl, sit, or even hold up her own head. She thinks the weakness is getting worse. The parents of the child are first cousins, and the mother's sister had one child who died before the age of 3 with similar symptoms. Hexosaminidase A activity was assayed in the blood and found to be absent. Which of the following will be found on fundoscopic examination of the child?

(M1.BC.14.1) A deficiency in which of the following lysosomal enzymes is inherited in a pattern similar to a deficiency of iduronate sulfatase (Hunter syndrome)?

(M1.BC.12.49) A 17-year-old high school student is found to have an inherited deficiency of alpha-galactosidase A. Skin biopsy shows accumulation of ceramide trihexose in the tissue. Which of the following abnormalities would be expected in this patient?