Fitzgerald P H, Pickering A F, Mercer J M, Miethke P M
Ann Hum Genet. 1975 May;38(4):417-28. doi: 10.1111/j.1469-1809.1975.tb00631.x.
Apparent acentric fragments which replaced a C-group chromosome in cultured blood lymphocytes from a woman patient were shown by autoradiography, G-banding and C-banding to be complete X chromosomes in which the centromere had divided prematurely in relation to the centromeres of other chromosomes in the same metaphase. Metaphases with multiple 'fragments' suggested that non-disjunction of the 'fragments' had occurred. This anomaly of the X chromosome was associated with increased aneuploidy of a C-group chromosome, presumed to be X. Premature centromere division of the X chromosome (PCD, X) appeared to be a mechanism of non-disjunction which caused significant monosomy and trisomy of the X chromosome in blood cells and skin fibroblasts. The frequency of cells with multiple fragments and the extent of the aneuploidy in 48 hr. blood cultures indicated that this mechanism of non-disjunction operated during mitosis both in vivo and in vitro. Premature centromere division occurred at a lower frequency in normal women donors, and was age-related, being four times more frequent in women 60 years and older than in women under 40. Associated with the higher frequency of PCD, the older women also showed evidence of increased X chromosome aneuploidy. Premature centromere division of the X chromosome is considered to be the mechanism of non-disjunction, causing the well-documented increased number of 45, -C metaphases in ageing women. Premature centromere division was rare in men, but an age effect was again suggested.
在一名女性患者培养的血液淋巴细胞中，取代一条C组染色体的明显无着丝粒片段，经放射自显影、G显带和C显带显示为完整的X染色体，其中着丝粒相对于同一中期其他染色体的着丝粒过早分离。具有多个“片段”的中期相提示“片段”发生了不分离。X染色体的这种异常与C组染色体（推测为X染色体）非整倍体增加有关。X染色体着丝粒过早分离（PCD，X）似乎是一种不分离机制，导致血细胞和皮肤成纤维细胞中X染色体出现明显的单体和三体。48小时血液培养中具有多个片段的细胞频率和非整倍体程度表明，这种不分离机制在体内和体外有丝分裂过程中均起作用。正常女性供体中着丝粒过早分离的频率较低，且与年龄相关，60岁及以上女性的频率是40岁以下女性的四倍。与较高的PCD频率相关，老年女性也显示出X染色体非整倍体增加的证据。X染色体着丝粒过早分离被认为是不分离机制，导致老年女性中记录充分的45，-C中期相数量增加。着丝粒过早分离在男性中很少见，但再次提示存在年龄效应。
