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Prader-Willi Syndrome (PWS) & Angelman Syndrome (AS)

Results usually available in 7-10 working days.

Prader-Willi Syndrome (PWS) is characterized by severe hypotonia and feeding difficulties in early infancy, followed in later infancy or early childhood by excessive eating and gradual development of morbid obesity, unless externally controlled. All patients have some degree of cognitive impairment; a distinctive behavioral phenotype is common. Hypogonadism is present in both males and females. Short stature is common. DNA-based methylation testing detects the absence of the paternally contributed Prader-Willi syndrome (PWS) region on chromosome 15q11.2-q13.

Angelman Syndrome (AS) is characterized by: 1) severe developmental delay or mental retardation; 2) severe speech impairment; 3) gait ataxia and/or tremulousness of the limbs; and 4) a unique behavior with an inappropriate happy demeanor that includes frequent laughing, smiling, and excitability. In addition, microcephaly and seizures are common.  Analysis of parent-specific DNA methylation imprints in the 15q11.2-q13 chromosome region detects approximately 78% of individuals with AS, including those with a deletion, uniparental disomy, or an imprinting defect; fewer than 1% of individuals have a cytogenetically visible chromosome rearrangement (i.e., translocation or inversion). UBE3A sequence analysis detects mutations in an additional ~11% of individuals.

The lab uses Methylation specific PCR (MSP) for sensitive detection of abnormal methylation pattern. This process employs an initial bisulfite reaction to modify the DNA, followed by PCR amplification with specific primers designed to distinguish methylated from unmethylated DNA.  This technology identifies over 99% of PWS cases and 78% of AS cases.