DNA methylation analysis in multi-locus imprinting disturbances

The aim of our study was to characterize the genotypic and phenotypic extent of multi-locus imprinting disturbances. Therefore, we analyzed the DNA methylation pattern of 37 individuals with different DNA methylation disturbances. Of these 37 individuals 17 were previously diagnosed with a multi-locus methylation disturbance (MLID) and the remaing 20 were diagnosed with a typical single locus imprinting disorder (SLID). We compared the DNA methylation of these 37 individuals to the DNA methylation of 38 evaluable individuals born small for gestational age. Our analysis revealed 21/37 individuals with a multi-locus methylation disturbances, characterzied by an aberrant DNA methylation in more than one imprintend gene region. Validation analyses were performed by bisulfite-pyrosequencing in the two imprinted gene regions ZDBF2 and FAM50B. Our analyses revealed each one patient previously diagnosed with Temple- and Angelman syndrome to have MLID. Furthermore, we showed that many of the aberrantly methylated imprinted gene regions in patients with MLID are not associated with the so far known typical imprinting disorders. Bisulfite converted DNA of peripheral blood from 37 individuals with DNA methylation disturbances and 39 individuals born small for gestationale age, serving as controls, were hybridized to the Illumina Infinium HumanMethylation450k Bead Chip array.