Genome-wide methylation profiling of Beckwith-Wiedemann syndrome patients without molecular confirmation after routine diagnostics

Beckwith-Wiedemann syndrome (BWS) is caused due to the disturbance of imprinted genes at chromosome 11p15. The molecular confirmation of this syndrome is possible in approximately 85% of the cases, whereas in the remaining 15% of the cases, the underlying defect remains unclear. The goal of our research was to identify new epigenetic loci related to BWS. We studied a group of 25 patients clinically diagnosed with BWS but without molecular conformation after DNA diagnostics and performed a whole genome methylation analysis using the HumanMethylation450 Array (Illumina).We found hypermethylation throughout the methylome in two BWS patients. The hypermethylated sites in these patients overlapped and included both non-imprinted and imprinted regions. This finding was not previously described in any BWS-diagnosed patient.Furthermore, one BWS patient exhibited aberrant methylation in four maternally methylated regions-IGF1R, NHP2L1, L3MBTL, and ZDBF2-that overlapped with the differentially methylated regions found in BWS patients with multi-locus imprinting disturbance (MLID). This finding suggests that the BWS phenotype can result from MLID without detectable methylation defects in the primarily disease-associated loci (11p15). Another patient manifested small but significant aberrant methylation in disease-associated loci at 11p near H19, possibly confirming the diagnosis in this patient.

Changes in mRNA expression profile underlie phenotypic adaptations in creatine kinase-deficient muscles

We have studied the mechanisms that regulate the remodeling of the glycolytic, mitochondrial and structural network of muscles of creatine kinase M (M-CK)/sarcomeric mitochondrial creatine kinase (ScCKmit) knockout mice by comparison of wild-type and mutant mRNA profiles on cDNA arrays. The magnitudes of changes in mRNA levels were most prominent in M-CK/ScCKmit (CK(-/-)) double mutants but did never exceed those of previously observed changes in protein level for any protein examined. In gastrocnemius of CK(-/-) mice we measured a 2.5-fold increase in mRNA level for mitochondrial encoded cytochrome c oxidase (COX)-III which corresponds to the increase in protein content. The level of the nuclear encoded mRNAs for COX-IV, H(+)-ATP synthase-C, adenine nucleotide translocator-1 and insulin-regulatable glucose transporter-4 showed a 1.5-fold increase, also in agreement with protein data. In contrast, no concomitant up-regulation in mRNA and protein content was detected for the mitochondrial inorganic phosphate-carrier, voltage-dependent anion channel and certain glycolytic enzymes. Our results reveal that regulation of transcript level plays an important role, but it is not the only principle involved in the remodeling of mitochondrial and cytosolic design of CK(-/-) muscles.