Cantu J M, Hernandez A, Plascencia L, Vaca G, Moller M, Rivera H
Ann Genet. 1980;23(3):183-6.
A 3-month-old boy with a 46,XY,--21,+t(21;21)(pter leads to q22.3::q22.3 leads to q11::p11 leads to pter) karyotype, implicating trisomy for the 21q11 leads to 21q22.2 segment and monosomy for the 21q22.3 sub-band, is described. Most of the clinical features corresponded to Down syndrome ; other signs such as large ears, prominent nasal bridge and retromicrognathia were interpreted as the expression of 21q22.3 monosomy. The abnormal monocentric chromosome had satellites and stalks on both ends as a result of a 21q;21q translocation followed by deletion of one centromere region. Despite similar stalk size and NOR-Ag positiveness a significantly higher association frequency of the centrometric end as compared to the acentric end was found. This observation suggests that the satellite association phenomenon is not exclusively NOR-dependent, but that the centromeric and/or p11 regions of acrocentrics also play an important role.
描述了一名3个月大的男孩，其核型为46,XY,--21,+t(21;21)(pter导致q22.3::q22.3导致q11::p11导致pter)，这意味着21q11至21q22.2区段三体性以及21q22.3亚带单体性。大多数临床特征与唐氏综合征相符；其他体征如大耳朵、鼻梁突出和小颌后缩被解释为21q22.3单体性的表现。由于发生了21q;21q易位，随后一个着丝粒区域缺失，异常的单中心染色体两端都有随体和柄。尽管柄的大小相似且NOR - Ag阳性，但发现着丝粒端的关联频率明显高于无着丝粒端。这一观察结果表明，随体关联现象并非完全依赖于核仁组织区，而是近端着丝粒染色体的着丝粒和/或p11区域也起着重要作用。
