A newborn has hypotonia, small mouth, almond-shaped eyes, and hypogonadism. Chromosomal analysis shows deletion of chromosome 15q11-q13 on the paternal chromosome. The diagnosis is:
- A Angelman syndrome
- B Cri du chat syndrome
- C Prader-Willi syndrome ✓
- D DiGeorge syndrome
Correct answer: C. Prader-Willi syndrome
Explanation
Prader-Willi syndrome results from loss of paternal 15q11-q13 (either deletion or maternal uniparental disomy), as paternally expressed genes in this region (SNRPN, NDN) are critical. Features include hypotonia at birth, developmental delay, hyperphagia, obesity, hypogonadism, and almond-shaped eyes. Angelman syndrome results from loss of maternal 15q11-q13 (UBE3A) and presents with 'happy puppet' syndrome; Cri du chat involves chromosome 5p deletion; DiGeorge involves 22q11 deletion.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.