Methylation Analysis (of chromosomes 14 and 15) is performed to detect imprinting abnormalities that can occur on these chromosomes. Imprinting disorders include:
- Maternal Uniparental Disomy (UPD) 14
- Caused by absence of the paternal copy of chromosome region 14q32.2.
- Paternal Uniparental Disomy (UPD) 14
- Caused by absence of the maternal copy of chromosome region 14q32.
- Paternal Uniparental Disomy (UPD) 15 (Angelman syndrome)
- Angelman syndrome (AS) is caused by abnormal or disrupted maternally imprinted UBE3A region within 15q11-q13.
- The combination of genetic testing offered at our laboratory, including methylation 15, UPD Array, and deletion/duplication analysis will detect an abnormality for approximately 89-90% of individuals with AS.
- Approximately 10-11% of individuals with AS will not have an identifiable AS-causing genetic abnormality due to either incorrect clinical diagnosis or limitations of current methods of testing.
- Maternal Uniparental Disomy (UPD) 15 (Prader-Willi syndrome)
- Prader-Willi syndrome (PWS) is caused by absence of the paternal copy of the PWS/Angelman syndrome region of chromosome 15.
- A combination of methylation, FISH, chromosomes, and/or UPD will detect a genetic abnormality in ~99% of individuals with PWS; our laboratory does not perform sequence analysis on the imprinting center which is the cause for less than 1% of individuals with PWS.
Methylation analysis is used to detect and identify the parental origin of deletions, uniparental disomy (UPD) and methylation defects occurring in the imprinted promoter regions of chromosomes 14 (MEG3/GTL2) & 15 (SNRPN).