Bayless-Underwood L, Cho S, Ward B, Robinson A
Clin Genet. 1983 Nov;24(5):359-64. doi: 10.1111/j.1399-0004.1983.tb00086.x.
Accurate interpretation of chromosomal variants is essential in prenatal diagnosis in order to distinguish polymorphisms from potential pathology in the fetus. This paper reports intra-uterine diagnosis of a satellited Yq in two unrelated families. The 29-year-old consultant in Case A sought prenatal diagnosis because of a maternal family history of Down syndrome. Case B was studied because of maternal age of 37. GTG banded chromosome analysis of cultured amniotic fluid cells from both cases revealed a 46,XY chromosome constitution with extra material present on the Yqter. This was interpreted to be satellite material. QFQ, CBG and AgNOR staining were performed. The material in question proved to be AgNOR positive, indicating that it was transcriptionally active for ribosomal RNA production during the last cell cycle. In addition, frequent satellite association between the Yqter and other acrocentric chromosomes was noted. These findings confirmed the initial interpretation. Other family members were studied and an AgNOR positive Yqs chromosome was confirmed in normal males in three generations of both families. The Yqs chromosome observed in the fetal cells was therefore considered a normal variant. The outcome of pregnancy in Case A was a phenotypically normal male. Case B had not delivered at the time of this writing. The origin of this satellite material on the Y chromosome is considered.
在产前诊断中，准确解读染色体变异对于区分胎儿的多态性与潜在病理情况至关重要。本文报告了两个无亲缘关系家庭中Yq随体的宫内诊断情况。病例A中的29岁顾问因唐氏综合征的母系家族史而寻求产前诊断。病例B因母亲年龄37岁而接受研究。对两个病例的羊水细胞进行GTG显带染色体分析，结果显示染色体组成为46,XY，Yqter存在额外物质，最初判定为随体物质。进行了QFQ、CBG和AgNOR染色，结果显示该物质为AgNOR阳性，表明它在上一个细胞周期中对于核糖体RNA的产生具有转录活性。此外，还发现Yqter与其他近端着丝粒染色体之间频繁出现随体联合。这些结果证实了最初的解读。对其他家庭成员进行了研究，两个家庭的三代正常男性中均证实存在AgNOR阳性的Yqs染色体。因此，胎儿细胞中观察到的Yqs染色体被认为是一种正常变异。病例A的妊娠结果是一个表型正常的男性。在撰写本文时，病例B尚未分娩。文中还对Y染色体上这种随体物质的起源进行了探讨。
