Kurosawa K, Kuromaru R, Imaizumi K, Nakamura Y, Ishikawa F, Ueda K, Kuroki Y
Division of Medical Genetics, Kanagawa Children's Medical Center, Japan.
Acta Genet Med Gemellol (Roma). 1992;41(4):301-10. doi: 10.1017/s0001566000002154.
A nine-year-old girl with short stature was referred to the department of pediatrics at Kyushu University. The clinical diagnosis was Turner syndrome; karyotypic analysis performed on peripheral blood, using GTG techniques, demonstrated a 45,X/47,XYY (17:83) mosaicism. Her twin brother, a phenotypically normal male, had the same karyotype; 45,X/47,XYY (3:97) on peripheral blood. Their skin fibroblast karyotypes showed the same mosaicism, ie. 45,X/47,XYY (41:59 and 31:69 respectively). On eleven biochemical genetic markers the twin pair were concordant, thus the likelihood of monozygosity was 0.99527034. In addition, the analysis of variable number of tandem repeat (VNTR) markers revealed the likelihood of monozygosity to be 0.99944386. The most plausible explanation of the X/XYY mosaicism was nondisjunction of the Y in the first cleavage division of the 46,XY zygote. A disproportionate rate of cell populations with 45,X and 47,XYY in the twinning process of the X/XYY embryo, especially in the germ lines, would result in discordant sex in twin pairs.
一名身材矮小的9岁女孩被转诊至九州大学儿科。临床诊断为特纳综合征；采用GTG技术对外周血进行核型分析，结果显示为45,X/47,XYY（17:83）嵌合体。她的双胞胎兄弟，表型正常的男性，外周血核型相同；45,X/47,XYY（3:97）。他们的皮肤成纤维细胞核型显示相同的嵌合体，即分别为45,X/47,XYY（41:59和31:69）。在11个生化遗传标记上，这对双胞胎是一致的，因此单合子性的可能性为0.99527034。此外，对可变串联重复序列（VNTR）标记的分析显示单合子性的可能性为0.99944386。对X/XYY嵌合体最合理的解释是46,XY合子第一次卵裂时Y染色体不分离。在X/XYY胚胎的孪生过程中，尤其是在生殖系中，具有45,X和47,XYY的细胞群比例不均衡，会导致双胞胎性别不一致。
