Angelman syndrome is characterized by severe motor and
mental retardation, microcephaly, ataxia, jerky limb
movements such as hand flapping, hyperactivity, seizures, absence of speech,
frequent smiling and outbursts of laughter, and unusual
facial features, characterized by a large mouth and jaw,
an open-mouthed expression, with a great propensity for
protruding the tongue.
A healthy person receives two copies of chromosome 15, one from the mother, the other from the father. However, in the region of the chromosome that is critical for Angelman syndrome, the maternal and paternal contributions express certain genes very differently. This is due to sex-specific epigenetic imprinting; the biochemical mechanism is DNA methylation. In a normal individual, the maternal allele is expressed and the paternal allele is specifically silenced in the developing brain. If the maternal contribution is lost or mutated, the result is Angelman syndrome.
The methylation test that is performed for Angelman syndrome is looking for methylation on the gene's neighbor SNRPN which is silenced by methylation on the maternal copy of the gene.
Methodology: methylation analysis
Purpose: Confirmation of Clinical Diagnosis/Screening test
ICD-10 Code: Q93.5
Test Requisition: Molecular Requisition
CPT Code: 81331 Cost: $438.00
Turn-around-time: 21 days
1. Lossie A, Driscoll D (1999). "Transmission of Angelman syndrome by an affected mother". Genet Med 1 (6): 262–6.
2. Williams CA, Angelman H, Clayton-Smith J et al. (1995). "Angelman syndrome: consensus for diagnostic criteria. Angelman syndrome Foundation". Am. J. Med. Genet. 56 (2): 237–8.
3. Buntinx IM, Hennekam RC, Brouwer OF et al. (March 1995). "Clinical profile of Angelman syndrome at different ages". American Journal of Medical Genetics 56 (2): 176–83.
4. White HE, Durston VJ, Harvey JF, Cross NC (2006). "Quantitative analysis of SNRPN(correction of SRNPN) gene methylation by pyrosequencing as a diagnostic test for Prader-Willi syndrome and Angelman syndrome". Clin. Chem. 52 (6): 1005–13.