Chinese Siblings with Prader-Willi Syndrome Inherited from Their Paternal Grandmother

Background: Prader-Willi syndrome (PWS) is a complex neurobehavioral disorder causedby failure of expression of paternally inherited genes in the PWS region of chromosome 15.Case characteristics: Two siblings who both met the inclusion criteria for clinical diagnosisof PWS during neonatal period. Outcome: Molecular genetic analysis demonstrated a 417-kb microdeletion within the 15q11.2 region inherited from siblings’ paternal grandmother,involving key genes of PWS, except for UBE3A, which may explain why their father andpaternal grandmother had a normal phenotype. Conclusion: The findings may be helpfulfor better understanding of the underlying mechanism of this rare imprinting defect