Study of DNA-methylation patterns at chromosome 15q11-q13 in children bornafter ICSI reveals no imprinting defects

The introduction of intracytoplasmic sperm injection (ICSI) has raised conc ern about safety in terms of a possible increase in the incidence of major congenital malformations, chromosomal aberrations or developmental problems . The possible influence of genetic imprinting on an ICSI procedure has not yet been investigated. We therefore studied the DNA-methylation status at a defined region in chromosome 15q11-q13 in 92 children born after an ICSI procedure. Imprinting defects in this region are associated with neurogenet ic disorders, e.g. Angelman syndrome (AS) and Prader-Willi syndrome (PWS). Blood samples were taken directly after birth and stored at -80 degreesC. G enomic DNA purification was performed from 3-7 mi EDTA-blood. Sodium bisulp hite treatment was carried out in order to distinguish methylated from unme thylated DNA by transferring the unmethylated nucleic acid cytosine into ur acil and leaving the methylated cytosine unchanged. Subsequently, a methyla tion-specific polymerase chain reaction (M-PCR) was performed. In all 92 ch ildren (83 from ICSI with ejaculated spermatozoa and nine from ICSI with no n-ejaculated spermatozoa), a regular DNA-methylation pattern was found in t he PWS/AS region. In none of the children were clinical symptoms of PWS or AS present. In conclusion, the results of this study do not indicate a high er risk of DNA-methylation defects in children born after ICSI.