VARIABILITY IN ALLELIC DNA METHYLATION IN SPERMATOZOA

In certain segments of human DNA, the methylation of deoxycytidine res idues has been found to be highly specific and interindividually conse rved. Imprinted DNA sequences in diploid primary cells show allele-spe cific differences in DNA methylation, usually with the active chromoso mal regions being unmethylated and the inactive regions being methylat ed. We show here that DNA from spermatozoa exhibits variations in alle lic methylation patterns. Since germ cells are haploid, individual spe rmatozoa can differ in DNA methylation patterns not only in the matern ally or paternally derived allele, but also within each allele.