#june2020mccqe1
A 1-year-old boy is brought to the pediatrician because his parents have recently noted a number of abnormalities. Although the child was normal at birth, he does not interact with others as his older sister did at the same age. His parents also note that he has coarse facial features. Physical examination reveals skeletal abnormalities and an umbilical hernia. Funduscopic examination shows corneal clouding. Additionally, the baby’s liver and spleen are enlarged, and his joints are stiff.
What is the most likely diagnosis?
Answer:
The most likely diagnosis is Hurler syndrome. This syndrome results from a defect in α-L-iduronidase, an enzyme essential to the degradation of dermatan sulfate and heparan sulfate. This disease is one of the mucopolysaccharidoses, a group of hereditary disorders characterized by defects in glycosaminoglycan (GAG) metabolism. Features that distinguish this disorder from the other lysosomal storage disorders include coarse facial features and corneal clouding. In hurler syndrome, the GAGs are not appropriately degraded in the lysosomes and are therefore deposited in various tissues. The disease is inherited in an autosomal recessive manner.
Hunter syndrome is another mucopolysaccharidosis. It is due to a deficiency of iduronate sulfatase and has X-linked inheritance. Unlike hurler syndrome, hunter syndrome does not present with corneal clouding, but affected patients may exhibit aggressive behavior
A 1-year-old boy is brought to the pediatrician because his parents have recently noted a number of abnormalities. Although the child was normal at birth, he does not interact with others as his older sister did at the same age. His parents also note that he has coarse facial features. Physical examination reveals skeletal abnormalities and an umbilical hernia. Funduscopic examination shows corneal clouding. Additionally, the baby’s liver and spleen are enlarged, and his joints are stiff.
What is the most likely diagnosis?
Answer:
The most likely diagnosis is Hurler syndrome. This syndrome results from a defect in α-L-iduronidase, an enzyme essential to the degradation of dermatan sulfate and heparan sulfate. This disease is one of the mucopolysaccharidoses, a group of hereditary disorders characterized by defects in glycosaminoglycan (GAG) metabolism. Features that distinguish this disorder from the other lysosomal storage disorders include coarse facial features and corneal clouding. In hurler syndrome, the GAGs are not appropriately degraded in the lysosomes and are therefore deposited in various tissues. The disease is inherited in an autosomal recessive manner.
Hunter syndrome is another mucopolysaccharidosis. It is due to a deficiency of iduronate sulfatase and has X-linked inheritance. Unlike hurler syndrome, hunter syndrome does not present with corneal clouding, but affected patients may exhibit aggressive behavior
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