Temple syndrome in a patient with variably methylated CpGs at the primary MEG3/DLK1 :IG-DMR and severely hypomethylated CpGs at the secondary MEG3 :TSS-DMR

Background The human chromosome 14q32.2 imprinted region harbors the primary MEG3/DLK1 :IG-differentially methylated region (DMR) and secondary MEG3 :TSS-DMR. The MEG3 :TSS-DMR can remain unmethylated only in the presence of unmethylated MEG3/DLK1 :IG-DMR in somatic tissues, but not in the placenta, because of a hierarchical regulation of the methylation pattern between the two DMRs. Methods We performed molecular studies in a 4-year-old Japanese girl with Temple syndrome (TS14). Results Pyrosequencing analysis showed extremely low methylation levels of five CpGs at the MEG3 :TSS-DMR and grossly normal methylation levels of four CpGs at the MEG3/DLK1 :IG-DMR in leukocytes. HumanMethylation450 BeadChip confirmed marked hypomethylation of the MEG3 :TSS-DMR and revealed multilocus imprinting disturbance (MLID) including mild hypomethylation of the H19/IGF2 :IG-DMR and mild hypermethylation of the GNAS A/B :TSS-DMR in leukocytes. Bisulfite sequencing showed markedly hypomethylated CpGs at the MEG3 :TSS-DMR and irregularly and non-differentially methylated CpGs at the MEG3/DLK1 :IG-DMR in leukocytes and apparently normal methylation patterns of the two DMRs in the placenta. Maternal uniparental disomy 14 and a deletion involving this imprinted region were excluded. Conclusions Such a methylation pattern of the MEG3/DLK1 :IG-DMR has not been reported in patients with TS14. It may be possible that a certain degree of irregular hypomethylation at the MEG3/DLK1 :IG-DMR has prevented methylation of the MEG3 :TSS-DMR in somatic tissues and that a hypermethylation type MLID has occurred at the MEG3/DLK1 :IG-DMR to yield the apparently normal methylation pattern in the placenta.