A medical student is reviewing the pathophysiology of several pediatric genetic and metabolic disorders during a clinical genetics rotation. Evaluate the clinical vignettes below and match each patient presentation with the most accurate description of its underlying biochemical or genetic defect.
- A 15-year-old adolescent presents with acute-onset right leg swelling and pain. Examination reveals a tall, thin habitus, arachnodactyly, and inferior subluxation of the lenses. The patient has a known history of moderate intellectual disability.Impaired conversion of homocysteine to cystathionine, leading to endothelial damage
- A 4-year-old boy is evaluated for choreoathetoid movements and severe intellectual disability. His parents report frequent episodes where he severely bites his own lips and fingers. His diapers occasionally contain an orange, sand-like precipitate.Defect in the purine salvage pathway, resulting in excessive de novo purine synthesis
- An 11-month-old infant is brought in for progressive weakness and loss of motor milestones. Examination shows hyperreflexia, an exaggerated startle response to noise, and a prominent cherry-red spot on the macula. Abdominal examination reveals no organomegaly.Failure to degrade GM2 ganglioside due to absent alpha-subunit of a lysosomal enzyme
- A 5-year-old boy presents with progressive joint stiffness and aggressive behavioral outbursts. Examination shows coarse facial features and nodular skin lesions over the scapulae. Slit-lamp examination demonstrates completely clear corneas.Deficient iduronate-2-sulfatase, causing accumulation of heparan and dermatan sulfate
Cevap
The correct pairings connect Homocystinuria with impaired cystathionine synthesis, Lesch-Nyhan syndrome with defective purine salvage, Tay-Sachs disease with GM2 ganglioside accumulation, and Hunter syndrome with iduronate-2-sulfatase deficiency.
Each vignette provides unique diagnostic clues that point to a specific biochemical defect. The tall patient with thrombosis and downward lens subluxation has homocystinuria. The boy with self-mutilation has Lesch-Nyhan syndrome. The infant with a cherry-red spot and no organomegaly has Tay-Sachs disease. The boy with coarse facies and clear corneas has Hunter syndrome.
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Anahtar Kavram
Clinical recognition and biochemical correlation of classical pediatric metabolic and genetic disorders (Homocystinuria, Lesch-Nyhan, Tay-Sachs, Hunter).