講演情報
[O20-3]複雑なX染色体重複領域を伴う症例におけるターゲットロングリードシーケンスを用いた構造解析およびPGT-Mセットアップについて
○真里谷 奨1,2,3, 七里 由衣3, 杉本 岳3, 河村 理恵3, 宮井 俊輔3, 稲垣 秀人3, 杉原 英志4, 池田 桂子1, 馬場 剛1, 石川 亜貴2, 庵前 美智子5, 中村 義晴5, 齋藤 豪1, 櫻井 晃洋2, 倉橋 浩樹3 (1.札幌医科大学 医学部 産婦人科学講座, 2.札幌医科大学 医学部 遺伝医学, 3.藤田医科大学 医科学研究センター 分子遺伝学研究部門, 4.藤田医科大学 研究支援推進本部 共同利用研究設備サポートセンター, 5.IVFなんばクリニック)
Objective: Pelizaeus-merzbacher disease (PMD) and MECP2 duplication syndrome are severe neurodevelopmental disorders of childhood onset. Both disorders are characterized by the presence of duplicated regions with chromosomal rearrangement of X chromosome. For PGT-M for these disorders, junction-specific PCR is useful to detect pathogenic variants directly. However, presence of normal sequence hinders the pre-clinical workup of the diagnostic PCR. In this study, we used nanopore long-read sequencing targeted X chromosome using adaptive sampling method to identify breakpoint junctions in the triplications. Methods: Sequencing was performed on a GridION long-read sequencer. To define target region for adaptive sampling, we used whole X chromosome for the determination of chromosomal rearrangement. Breakpoint junctions of duplicated region were detected by detailed analysis of discordant reads. Results: By long-read sequencing, we successfully identified junctions in one PMD case with PLP1 triplication and the other MECP2 triplication case. Surprisingly, the duplicated region involving MECP2 was inserted to 45 Mb proximal to the original position. With the help of precise mapping of the pathogenic variant, we could avoid the potential misinterpretation of pathogenic allele by STR (short tandem repeat) haplotyping in PGT-M if meiotic recombination undergoes at this 45Mb interval. Conclusion: Long-read sequencing with adaptive sampling is a beneficial method for the identification of junctions of chromosomal complex structural rearrangements for PGT-M pre-clinical workup.