Prader-Willi syndrome results from deletion of the paternal chromosome 15q11-q13 region. If instead the maternal 15q11-q13 region is deleted in the same chromosomal locus, the resulting clinical syndrome is:

• A Beckwith-Wiedemann syndrome
• B Rett syndrome
• C Russell-Silver syndrome
• D Angelman syndrome ✓

Explanation

Prader-Willi and Angelman syndromes are the classic example of genomic imprinting: both result from aberrations at chromosome 15q11-q13 but differ by parental origin. Paternal deletion causes Prader-Willi (hyperphagia, hypogonadism, intellectual disability) because the paternally expressed genes SNRPN and NDN are silenced, while the maternal allele is normally imprinted (silenced). Maternal deletion causes Angelman syndrome (seizures, absent speech, happy demeanor, 'puppet gait') because the maternally expressed UBE3A gene is lost, and the paternal UBE3A is imprinted. Beckwith-Wiedemann involves chromosome 11p15.5.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.