Chromosome 6q24 methylation defects are uncommon in childhood-onset non-autoimmune diabetes mellitus patients born appropriate- or large-for-gestational age.

Abstract

Methylation defects in the imprinting locus at chromosome 6q24 result in transient neonatal diabetes and small-for-gestational age (SGA) births (1). These phenotypes are primarily ascribed to the overexpression of PLAGL1, a paternally expressed gene on 6q24 that regulates cell cycle and apoptosis (2). Paternal uniparental disomy involving 6q24, as well as copy-number gains of paternal PLAGL1 alleles and epimutations in maternal alleles, have been identified as the causes of hypomethylation at the differentially methylated region (DMR) of PLAGL1 (3, 4). Recently, Yorifuji et al. reported the identification of 6q24 uniparental disomy in three patients with childhood-onset non-autoimmune diabetes mellitus (5). The three patients were identified through methylation-specific PCR analysis of the PLAGL1 DMR of 113 patients clinically suspected of having maturity-onset diabetes of the young (MODY). These results expanded the phenotypic consequences of 6q24 methylation defects to include MODY-like manifestations without a history of neonatal diabetes. However, the frequency of 6q24 methylation defects among patients with childhood-onset non-autoimmune diabetes remained unknown.