Prader‑Willi/Angelman Syndrome, DNA Methylation Analysis

Casandra

Casandra Test Code QD35478Version 1 (DRAFT)

Performing Lab

Lab Quest DiagnosticsLab Test ID 11369CPT Code 81331

Prader‑Willi/Angelman Syndrome, DNA Methylation Analysis

Clinical Use

Use

This assay aids in the diagnosis of Prader‑Willi syndrome and Angelman syndrome by detecting aberrant DNA methylation patterns in chromosome 15q11‑q13, encompassing abnormalities due to deletions, uniparental disomy (UPD), or imprinting defects. It can confirm over 99% of Prader‑Willi cases and approximately 80% of Angelman syndrome cases, serving as a definitive diagnostic tool when FISH results are normal or inconclusive. ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/clinical-education-center/faq/pwsfish?utm_source=openai))

Special Instructions

Performed by Quest Diagnostics Nichols Institute San Juan Capistrano. No prior or post‑test genetic counseling is explicitly required according to GTR information (state law may apply to consent). Insurance authorization may be required for outpatient collections. ([rchsd.org](https://www.rchsd.org/lab-test/prader-willi-angelman-syndrome-dna-methylation-analysis-11369/?utm_source=openai))

Limitations

This methylation‑specific PCR approach detects methylation abnormalities but cannot distinguish between deletion, uniparental disomy, or imprinting defect; further testing (e.g., FISH or CMA) may be needed for etiologic clarification. It does not detect mosaicism. ([ncbi.xyz](https://www.ncbi.xyz/gtr/tests/590570/?utm_source=openai))

Test Details

New York Approved

Methodology

PCR-based (PCR)

Biomarkers

Methylation‑specific PCR targeting the SNRPN locus in chromosome 15q11‑q13 to detect abnormal methylation patterns indicative of Prader‑Willi or Angelman syndromes.

SNRPN

Gene

Methylation pattern at SNRPN • Other • Categorical (e.g., Positive / Negative / Indeterminate)