Green J E, Rosenbaum K N, Rapoport S I, Schapiro M B, White B J
Interinstitute Medical Genetics Program, National Institutes of Health, Bethesda.
Clin Genet. 1989 Apr;35(4):243-50. doi: 10.1111/j.1399-0004.1989.tb02938.x.
In order to determine whether nucleolus organizing region (NOR) heteromorphisms of the acrocentric chromosomes could identify individuals at risk for having offspring with trisomy 21, a comparison was made between 43 parents of individuals with Down syndrome and 39 controls. NORs, as visualized by silver staining, were analyzed by mean number per cell, average size, total NOR "mass" per cell (designated mean score per cell) and by mean number of acrocentric chromosome satellite associations per cell. No "double NOR" variants (dNOR) were found in either the control or study group in contrast to observations of others (Jackson-Cook et al. 1985). The risk for having a child with trisomy correlated with a higher frequency of associations and number of NORs per cell, but slightly lower average NOR size. Although these group differences were statistically significant, specific types of NOR variants such as enlarged or dNORs were not associated with the risk of having trisomy 21 offspring. The constancy of NOR mass per cell in our control and study groups indicates that NOR activity remains constant, even though distribution of the rRNA genes (variation in number and size of NORs on the 10 acrocentrics) may vary.
为了确定近端着丝粒染色体的核仁组织区（NOR）多态性是否能够识别生育21三体后代风险较高的个体，对43名唐氏综合征患者的父母和39名对照者进行了比较。通过银染显示的NORs，从每个细胞的平均数、平均大小、每个细胞的总NOR“质量”（指定为每个细胞的平均得分）以及每个细胞近端着丝粒染色体随体联合的平均数方面进行分析。与其他人的观察结果（Jackson-Cook等人，1985年）相反，在对照组或研究组中均未发现“双NOR”变体（dNOR）。生育三体患儿的风险与联合频率较高以及每个细胞的NOR数量较多相关，但平均NOR大小略低。尽管这些组间差异具有统计学意义，但特定类型的NOR变体，如增大的或dNORs，与生育21三体后代的风险并无关联。我们对照组和研究组中每个细胞NOR质量的稳定性表明，即使rRNA基因的分布（10条近端着丝粒染色体上NOR数量和大小的变化）可能有所不同，NOR活性仍保持恒定。
