DNA Methylation in Huntington's Disease

Methylation of cytosine in CpG dinucleotides is the major DNA modification in mammalian cells that is a key component of stable epigenetic marks. This modification, which on the one hand is reversible, while on the other hand, can be maintained through successive rounds of replication plays roles in gene regulation, genome maintenance, transgenerational epigenetic inheritance, and imprinting. Disturbed DNA methylation contributes to a wide array of human diseases from single-gene disorders to sporadic metabolic diseases or cancer. DNA methylation was also shown to affect several neurodegenerative disorders, including Huntington's disease (HD), a fatal, monogenic inherited disease. HD is caused by a polyglutamine repeat expansion in the Huntingtin protein that brings about a multifaceted pathogenesis affecting several cellular processes. Research of the last decade found complex, genome-wide DNA methylation changes in HD pathogenesis that modulate transcriptional activity and genome stability. This article reviews current evidence that sheds light on the role of DNA methylation in HD.