This constellation of features—hypotonia, macroglossia, brachycephaly, single palmar crease, short broad hands with clinodactyly—is classic for Down syndrome (Trisomy 21).

Toronto Notes 2023 – Pediatrics, “Genetic Syndromes”:

“Trisomy 21 features include hypotonia, upslanting palpebral fissures, epicanthic folds, flat nasal bridge, brachycephaly, macroglossia, single palmar crease, and clinodactyly.”

MCCQE1 Objectives (Pediatrics > 78-3: Congenital and Genetic Disorders):

“Candidates must recognize key dysmorphic features associated with common genetic syndromes including Trisomy 21.”

Prader-Willi and congenital hypothyroidism may have hypotonia but lack the full phenotypic pattern. Turner syndrome is seen in females with short stature and webbed neck. Fetal alcohol syndrome presents with smooth philtrum and microcephaly.

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