Department of Obstetrics and Gynecology, PLA General Hospital, Beijing, 100853, China.
Prenatal Diagnosis Center of Hunan Province, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, 410008, China.
J Assist Reprod Genet. 2020 Mar;37(3):509-516. doi: 10.1007/s10815-020-01702-z. Epub 2020 Feb 5.
Approximately 1% of individuals who carry a balanced reciprocal translocation (BRT) are subfertile. Current karyotyping does not have the resolution to determine whether the breakpoints of the involved chromosomes perturb genes important for fertility. The aim of this study was to apply single-molecule optical mapping (SMOM) to patients presenting for IVF (in vitro fertilization) to ascertain whether the BRT disrupted any genes associated with normal fertility.
Nine subfertile patients with different BRTs were recruited for the study. Methyltransferase enzyme DLE1 was used to fluorescently label their genomic DNA samples at the recognition motif CTTAAG. The SMOM was performed on the Bionano platform, and long molecules aligned against the reference genome hg19 to identify the breakpoint regions. Mate-pair and PCR-Sanger sequencing were used to confirm the precise breakpoint sequences.
Both breakpoint regions in each of the nine BRTs were finely mapped to small regions of approximately 10 Kb, and their positions were consistent with original cytogenetic banding patterns determined by karyotyping. In three BRTs, breakpoints disrupted genes known to be associated with male infertility, namely NUP155 and FNDC3A [46,XY,t(5;13)(p15;q22)], DPY19L1 [46,XY,t(1;7)(p36.3;p15), and BAI3 [46,XY,t(3;6)(p21;q16)].
The SMOM has potential clinical application as a rapid tool to screen patients with BRTs for underlying genetic causes of infertility and other diseases.
大约 1%携带平衡易位（BRT）的个体存在生育力低下的问题。目前的核型分析无法确定涉及染色体的断点是否会扰乱与生育力相关的重要基因。本研究旨在应用单分子光学图谱（SMOM）对接受体外受精（IVF）的患者进行检测，以确定 BRT 是否破坏了任何与正常生育力相关的基因。
招募了 9 名患有不同 BRT 的不育患者参与该研究。甲基转移酶酶 DLE1 用于在识别基序 CTTAAG 处对其基因组 DNA 样本进行荧光标记。SMOM 在 Bionano 平台上进行，长分子与参考基因组 hg19 对齐以识别断点区域。使用 Mate-pair 和 PCR-Sanger 测序来确认精确的断点序列。
9 个 BRT 中的每个 BRT 的两个断点区域都被精细地映射到大约 10 kb 的小区域，并且它们的位置与通过核型分析确定的原始细胞遗传学带型一致。在 3 个 BRT 中，断点破坏了与男性不育相关的已知基因，即 NUP155 和 FNDC3A [46,XY,t(5;13)(p15;q22)]、DPY19L1 [46,XY,t(1;7)(p36.3;p15)]和 BAI3 [46,XY,t(3;6)(p21;q16)]。
SMOM 具有作为快速工具筛查 BRT 患者潜在遗传原因导致的不育症和其他疾病的潜在临床应用。
