Prader-Willi Syndrome

A syndrome characterized by severe hypotonia, poor feeding in early infancy followed later in infancy by excessive eating that, can lead to obesity if left unchecked. Children with PWS show developmental delay, mild-to-moderate mental retardation with multiple learning disabilities. Hypogonadism is present in females and males. Short stature and small hands and feet are also common.

 Prader-Willi syndrome is due to a chromosome deletion involving loss of material from chromosome region 15q11-q13. The loss is consistently from the father's contribution of chromosome region 15q11-q13. A child with P'wS can have two copies of chromosome region 15q11-13 but both will be from the mother. The opposite condition occurs in patients with Angelman syndrome, with the deletion occurring on the maternal region.

There is currently no specific treatment or cure for PWS. Parents are advised to limit consumption of high-calorie foods, and to use techniques such as special education, speech therapy, and physical therapy to maximize the child's potential. Severe psychiatric illness is common in PWS adults. FISH studies are also available to assist in the diagnosis of this disorder.

Methylation analysis detects approximately 99% of patients with PWS. Approximately 70% of PWS patients will demonstrate a deletion of 15q11.2-q13 that can be detected by FISH Analysis or CMA.

Methodology: Southern Blot

Purpose: Confirmation of Clinical Diagnosis

ICD-9 Code 759.81

Test Requisition: Molecular Requisition

CPT Code: 81331 Cost: $388.00

Turn-around-time: 21 days