Genomic imprinting explains why Prader-Willi syndrome and Angelman syndrome both arise from deletion of 15q11-q13 yet have distinct phenotypes. Which statement is correct?

• A Maternal deletion of 15q11-q13 causes Angelman syndrome; paternal deletion causes Prader-Willi syndrome
• B Both syndromes result from maternal deletion, but differ in epigenetic modification
• C The parent of origin is irrelevant; clinical differences reflect the extent of the deletion
• D Paternal deletion of 15q11-q13 causes Angelman syndrome; maternal deletion causes Prader-Willi syndrome ✓

Explanation

Genomic imprinting means that certain genes are expressed only from a specific parental allele. In 15q11-q13: the paternally imprinted region (normally expressed only from the father) contains SNRPN and NDN genes — paternal deletion → Prader-Willi syndrome. The UBE3A gene is maternally expressed; maternal deletion (or paternal UPD) → Angelman syndrome. So paternal deletion causes Prader-Willi and maternal deletion causes Angelman syndrome.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.