Petersen M B, Tranebjaerg L, McCormick M K, Michelsen N, Mikkelsen M, Antonarakis S E
Department of Medical Genetics, John F. Kennedy Institute, Glostrup, Denmark.
Am J Med Genet Suppl. 1990;7:104-9. doi: 10.1002/ajmg.1320370721.
We present 2 patients with dup(21q). Patient MP01 had mild mental retardation, facial findings characteristic of Down syndrome (DS), and a terminal duplication of chromosome 21. His karyotype was 46,XY,dup(21) (q22.1-qter). Patient MP03 had mild mental retardation, minor anomalies not characteristic of DS, and a duplication of the proximal long arm of chromosome 21, karyotype 46,XX,dup(21) (q11.2-q21.2). The patients were studied with single-copy DNA sequences from 20 loci on chromosome 21 to characterize the extent of the duplicated regions at the DNA level. DNA loci from D21S55 to COL6A1 were triplicated in patient MP01 while loci from D21S13 to D21S8 were triplicated in patient MP03. Our results support the hypothesis of a critical region of chromosome 21, which in triplicate is responsible for many of the facial changes associated with DS. Other genes outside this region may also contribute to other abnormalities observed in DS.
我们报告了2例21号染色体长臂重复（dup(21q)）的患者。患者MP01有轻度智力障碍、具有唐氏综合征（DS）特征的面部表现以及21号染色体末端重复。他的核型为46,XY,dup(21) (q22.1-qter)。患者MP03有轻度智力障碍、不具有DS特征的轻微异常以及21号染色体长臂近端重复，核型为46,XX,dup(21) (q11.2-q21.2)。使用来自21号染色体上20个位点的单拷贝DNA序列对这些患者进行研究，以在DNA水平上表征重复区域的范围。在患者MP01中，从D21S55到COL6A1的DNA位点呈三倍体，而在患者MP03中，从D21S13到D21S8的位点呈三倍体。我们的结果支持21号染色体关键区域的假说，该区域三倍体导致了许多与DS相关的面部变化。该区域之外的其他基因也可能导致在DS中观察到的其他异常。
