Nguyen H P, Riess A, Krüger M, Bauer P, Singer S, Schneider M, Enders H, Dufke A
Department of Medical Genetics, University of Tuebingen, Tuebingen, Germany.
Cytogenet Genome Res. 2009;125(1):26-32. doi: 10.1159/000218745. Epub 2009 Jul 14.
Many autosomal monosomies are presumed to end in arrested growth in the first few mitoses, prior even to the time of implantation, with possibly some proceeding to the stage of occult abortion. The single exception may be monosomy 21, although this has been questioned, with most earlier reports of monosomy 21 recently re-interpreted as being due to an unbalanced translocation involving chromosome 21. Here we report a female infant with a mosaic trisomy 21/monosomy 21 karyotype. While the karyotype 46,XX,i(21)(q10) is detected in all metaphases investigated in lymphocytes, mosaicism with the karyotype 46,XX,i(21)(q10)[31]/45,XX, -21[12] is seen in fibroblasts from a skin biopsy. Dysmorphic facial features and multiple malformations remarkably resemble cases of monosomy 21 that have been described in the literature. This suggests a dominant phenotypic effect of loss of one chromosome 21. Detailed clinical description, results of gene dosage studies, and cytogenetic analysis will be presented.
许多常染色体单体被认为在最初几次有丝分裂中就会停止生长，甚至在着床之前，可能有些会发展到隐性流产阶段。唯一的例外可能是21号染色体单体，尽管这一点存在争议，早期大多数关于21号染色体单体的报道最近被重新解释为是由于涉及21号染色体的不平衡易位所致。在此，我们报告一名患有21号染色体三体/单体嵌合体核型的女婴。虽然在淋巴细胞所有研究的中期相中均检测到核型46,XX,i(21)(q10)，但在皮肤活检的成纤维细胞中可见核型46,XX,i(21)(q10)[31]/45,XX,-21[12]的嵌合体。面部畸形特征和多种畸形与文献中描述的21号染色体单体病例极为相似。这表明丢失一条21号染色体会产生显性表型效应。将给出详细的临床描述、基因剂量研究结果和细胞遗传学分析。
