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

Area of Science:

• Genetics
• Molecular Biology
• Human Diseases

Background:

• Prader-Willi Syndrome (PWS) is a complex genetic disorder caused by genomic imprinting defects on chromosome 15q11-13.
• PWS is clinically defined by hypotonia, hyperphagia, obesity, developmental delays, and characteristic facial features.
• Microdeletions in the PWS critical region account for a significant majority (65-70%) of PWS cases.

Observation:

• The study employed physical and laboratory examinations for clinical PWS diagnosis and identification of novel features.
• Bisulfite-specific sequencing was utilized for initial screening of the PWS critical region.
• High-density array comparative genomic hybridization (array CGH) was used for precise delineation of genetic alterations.

Findings:

• Bisulfite-specific sequencing revealed homozygous hypermethylation of a critical CpG island within the PWS region.
• Array CGH identified a 2.22 Mb type II microdeletion, encompassing key genes including MKRN3, MAGEL2, NDN, and SNURF-SNRPN.
• A previously unreported clinical manifestation, metacarpophalangeal joint rigidity, was observed in the PWS patient.

Implications:

• Array CGH, following bisulfite sequencing, offers a feasible and accurate diagnostic approach for PWS microdeletions.
• The identification of a novel clinical feature expands the phenotypic spectrum of Prader-Willi Syndrome.
• This research contributes to a better understanding of the genetic and clinical complexities of PWS.