Match each pediatric patient's clinical presentation with the correct underlying genetic or enzymatic defect.
- A 9-month-old infant presenting with developmental regression, seizures, sparse, depigmented, kinky hair, and notably low serum ceruloplasmin.Defect in an ATP7A-encoded copper-transporting ATPase
- A 6-month-old infant presenting with extreme irritability, severe hypertonia, absent deep tendon reflexes, and diffuse central demyelination on neuroimaging.Deficiency of galactocerebrosidase
- A 5-day-old neonate presenting with profound hypotonia, a large anterior fontanelle, hepatomegaly, elevated very-long-chain fatty acids (VLCFAs), and calcific stippling of the epiphyses.Mutations in PEX genes leading to defective peroxisome biogenesis
- A 4-month-old infant presenting with severe generalized hypotonia, massive biventricular hypertrophy on echocardiography, normal fasting blood glucose, and elevated serum creatine kinase.Deficiency of lysosomal acid alpha-1,4-glucosidase
Answer
The correct matches are: the infant with kinky hair and low ceruloplasmin has an ATP7A defect (Menkes disease); the infant with irritability and absent reflexes has galactocerebrosidase deficiency (Krabbe disease); the neonate with elevated VLCFAs has PEX gene mutations (Zellweger syndrome); and the infant with cardiomegaly and normal glucose has lysosomal acid alpha-1,4-glucosidase deficiency (Pompe disease).
Each clinical vignette provides highly specific features pathognomonic for individual genetic and metabolic defects. Menkes disease is driven by defective intestinal copper transport (ATP7A), leading to low ceruloplasmin and kinky hair. Krabbe disease (galactocerebrosidase deficiency) destroys both central and peripheral myelin, leading to absent reflexes. Zellweger syndrome results from failed peroxisome biogenesis (PEX genes), leading to toxic accumulation of VLCFAs and characteristic skeletal changes. Pompe disease (acid alpha-1,4-glucosidase deficiency) represents a lysosomal inability to break down glycogen, resulting in severe early-onset hypertrophic cardiomyopathy without altering systemic blood glucose levels.
Step-by-Step Solution
Key Concept
Complex pediatric metabolic and genetic disorders can be distinguished by specific clinical phenotypes: copper transport defects (Menkes disease) feature kinky hair; leukodystrophies (Krabbe disease) show combined central and peripheral demyelination; peroxisomal biogenesis disorders (Zellweger syndrome) present with elevated VLCFAs and dysmorphism; and lysosomal storage diseases (Pompe disease) feature severe cardiomyopathy without hypoglycemia.