Precise microdeletion detection of Prader-Willi Syndrome with array comparative genome hybridization

Objective: Prader-Willi Sydrome (PWS) is a human disorder related to genomic imprinting defect on 15q11-13. It is characterized by a series of classic features such as hypotonia, hyperphagia, obesity, osteoporosis, typical facial and body dysmorphosis, hypogonadism, mental and behaviour disorders. Our study was designed to precisely detect the microdeletions, which accounts for 65%-70% of the PWS.

Methods: Physical and laboratory examinations were firstly performed to diagnose PWS clinically, and to discover novel clinical features. Then the patient was screened with bisulfite-specific sequencing and precisely delineated through high-density array CGH.

Results: With the bisulfite-specific sequencing, the detected CpG island in the PWS critical region was found homozygously hypermethylated. Then with array CGH, a 2.22 Mb type II microdeletion was detected, covering a region from MKRN3, MAGEL2, NDN, PWRN2, PWRN1, C12orf2, SNURF-SNRPN, C/D snoRNAs, to distal of UBE3A.

Conclusions: Array CGH, after the fast screening of Bisulfite-specific sequencing, is a feasible and precise method to detect microdeletions in PWS patients. A novel feature of metacarpophalangeal joint rigidity was also presented, which is the first time reported in PWS.