講演情報
[S4-4]ロングリードシークエンサーを用いた神経・筋疾患の疾患ゲノム・メチル化解析
○水口 剛 (横浜市立大学大学院医学研究科 遺伝学)
Despite recent advances in short-read sequencing methods, there is still difficulty in studying regions of repetitive sequences in human genome such as pathogenic repeat expansions. Long-read sequencing (LRS) technologies can directly read > 10 kb of single-molecule DNA, and hitherto unsequenceable repetitive regions. Moreover, this technology can simultaneously examine the epigenomic change by detecting 5-methylcytosine (5-mC) with no further experimental manipulations. We applied LRS to sporadic cases with neuronal intranuclear inclusion disease (NIID) and their phenotypically normal parents to explore the genetic origin of GGC repeat expansion mutation of NOTCH2NLC. Surprisingly, asymptomatic fathers had much longer expansions compared with their affected offspring, showing a possible paternal-biased inheritance of expansion mutation in (at least some) sporadic cases. We also identified an aberrant CpG hypermethylation of NOTCH2NLC in asymptomatic fathers, indicating the distinct functional consequences of two different classes of GGC expansion among fathers and their affected offspring. These observations suggest that GGC repeat expansion in NOTCH2NLC might have disease causing range, and that when the size of the expansion exceeds this range, it tends to be CpG hypermethylated, leading to non-pathogenicity. Detection of simultaneous genetic and epigenetic alteration using LRS will be broadly applied in many research areas.