Fukushi Daisuke, Kurosawa Kenji, Suzuki Yasuyo, Suzuki Kaoru, Yamada Kenichiro, Watanabe Seiji, Yokochi Kenji, Wakamatsu Nobuaki
Department of Genetics, Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, Japan.
Division of Medical Genetics, Kanagawa Children's Medical Center, Yokohama, Kanagawa, Japan.
Am J Med Genet A. 2017 Aug;173(8):2201-2209. doi: 10.1002/ajmg.a.38313. Epub 2017 Jun 9.
Partial trisomy 2p syndrome is occasionally associated with neural tube defects (NTDs), such as anencephaly, encephalocele, and spina bifida, in addition to common features of intellectual disability, developmental delay, and characteristic facial appearance. The 2p24 region has been reported to be associated with NTDs. Here, we report the cases of 2 siblings with trisomy 2p24.3-pter and monosomy 5p14.3-pter caused by the paternal translocation t(2;5)(p24.3;p14.3). Of the two siblings, the elder sister had spina bifida. We determined the nucleotide sequences of the chromosomal breakpoints and found that the sizes of trisomy 2p and monosomy 5p segments were 18.77 and 17.89 Mb, respectively. NTDs were present in four of seven previously reported patients with trisomy 2p and monosomy 5p as well as in one of the two patients examined in the present study. Although the monosomy 5p of the nine patients were similar in size, the two patients reported here had the smallest size of trisomy 2p. When the clinical features of the nine patients were compared to the present two patients, the elder sister had postaxial polydactyly of the left foot in addition to the characteristic facial appearance and spina bifida, indicating that these features were associated with trisomy 2p24.3-pter. To our knowledge, this is the first study on spina bifida to determine the nucleotide sequences of breakpoints for trisomy 2p24.3-pter and monosomy 5p14.3-pter. Increased gene dosages of dosage-sensitive genes or genes at the trisomy segment (2p24.3) of the presented patients could be associated with NTDs of patients with trisomy 2p.
除了智力残疾、发育迟缓以及典型面部外观等常见特征外，2p部分三体综合征偶尔还与神经管缺陷（NTDs）相关，如无脑儿、脑膨出和脊柱裂。据报道，2p24区域与神经管缺陷有关。在此，我们报告了2例由父亲的t(2;5)(p24.3;p14.3)易位导致的2p24.3 - pter三体和5p14.3 - pter单体的同胞病例。在这两名同胞中，姐姐患有脊柱裂。我们确定了染色体断点的核苷酸序列，发现三体2p和单体5p片段的大小分别为18.77和17.89 Mb。在先前报道的7例2p三体和5p单体患者中有4例存在神经管缺陷，本研究检测的2例患者中有1例存在神经管缺陷。尽管9例患者的5p单体大小相似，但此处报道的2例患者的2p三体大小最小。将9例患者与本研究的2例患者的临床特征进行比较时，姐姐除了具有典型面部外观和脊柱裂外，左脚还有轴后多指畸形，表明这些特征与2p24.3 - pter三体有关。据我们所知，这是第一项针对脊柱裂测定2p24.3 - pter三体和5p14.3 - pter单体断点核苷酸序列的研究。所呈现患者三体片段（2p24.3）中剂量敏感基因或基因的基因剂量增加可能与2p三体患者的神经管缺陷有关。
