The American College of Medical Genetics has described two approaches to laboratory diagnosis. The first approach, to be used in cases with a high degree of suspicion of AS or PWS, is DNA methylation analysis which will detect cases caused by deletion, UPD or imprint defects. DNA methylation analysis can distinguish between the maternal methylated and paternal unmethylated copies of a gene in the 15q11.2 region. An exclusively paternal pattern is observed in cases of AS due to deletion, UPD and imprint control mutations. An exclusively maternal pattern is observed in cases of PWS due to deletion, UPD and imprint control mutations. If the results are negative, chromosome analysis should be performed to rule out chromosome abnormalities.

• Southern blot analysis using the SRNPN probe.

• Blood EDTA (purple top) tubes:  

            Newborn: minimum 2-3 mL          

            Child/Adult: prefer 2 tubes of 3-5 mL

• Prenatal testing: Please contact the laboratory for instructions.

TURNAROUND TIME: 3 weeks

CPT CODES: 83890, 83892x6, 83894, 83896, 83897, 83912