AB058. Prader-Willi syndrome: clinical and genetic features

Background: Prader-Willi syndrome (PWS) is a complex multisystem genetic disorder that results from the lack of expression of paternal inherited imprinted genes on chromosome 15q11-13. PWS is characterized by severe infantile hypotonia; hypogonadism; obesity and hyperphagia; developmental delay, characteristic facial features, short stature; a distinctive behavioral phenotype. This study was performed to delineate the clinical and genetic features of patients diagnosed PWS at National Children’s Hospital, Hanoi, Vietnam.

Methods: A total of 118 patients were collected in the descriptive study from 2007 to 2017, they were diagnosed PWS by Holm’s criteria. All patients had karyotype and fluorescence in situ hybridization (FISH) performed at National Children’s Hospital, Hanoi. For the patients with no deletion detected by FISH, their specimens [10] were sent to other laboratories for SNRPN methylation-specific PCR (MS-PCR).

Results: All patients were found to have normal karyotype and 88/118 patients had deletion as demonstrated by FISH. Among 10 patients with MS-PCR performed, 8 patients revealed only maternal part of 15q11-13. Male:female ratio was 64%:36%. In regards to age at diagnosis, 10 (8.5%) patients were diagnosed in neonatal period; 68 (58.3%) patients diagnosed before 24 months. The mean age at diagnosis was 42.3 months. 86.6% of patients were found to have hypotonia. Of those 108 patients diagnosed after neonatal period, 33.3% of patients had obesity and 82% of patients had hyperphagia. Total of 88% of patients had hypogonadism.

Conclusions: Our study showed good sensitivity and specificity of Holm’s criteria in diagnosing PWS caused by 15q11-13 deletion. Based on clinical features more PWS patients should be diagnosed early.

Keywords: Prader-Willi syndrome (PWS); clinical features; fluorescence in situ hybridization (FISH); methylation-specific PCR (MS-PCR)