Blouin J L, Avramopoulos D, Pangalos C, Antonarakis S E
Center for Medical Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21287-3914.
Am J Hum Genet. 1993 Nov;53(5):1074-8.
Uniparental disomy (UPD) involving several different chromosomes has been described in several cases of human pathologies. In order to investigate whether UPD for chromosome 21 is associated with abnormal phenotypes, we analyzed DNA polymorphisms in DNA from a family with de novo Robertsonian translocation t(21q;21q). The proband was a healthy male with 45 dup(21q) who was ascertained through his trisomy 21 offspring. No phenotypic abnormalities were noted in the physical exam, and his past medical history was unremarkable. We obtained genotypes for the proband and his parents' leukocyte DNAs from 17 highly informative short sequence repeat polymorphisms that map in the pericentromeric region and along the entire length of 21q. The order of the markers has been previously determined through the linkage and physical maps of this chromosome. For the nine informative markers there was no maternal allele contribution to the genotype of the proband; in addition, there was always reduction to homozygosity of a paternal allele. These data indicated that there was paternal uniparental isodisomy for chromosome 21 (pUPiD21). We conclude that pUPiD21 is not associated with abnormal phenotypes and that there are probably no imprinted genes on chromosome 21.
在几例人类疾病中已描述了涉及几种不同染色体的单亲二体性（UPD）。为了研究21号染色体的UPD是否与异常表型相关，我们分析了一个患有新发罗伯逊易位t(21q;21q)的家族DNA中的DNA多态性。先证者是一名健康男性，核型为45 dup(21q)，通过其21三体综合征的后代得以确定。体格检查未发现表型异常，其既往病史也无特殊。我们从17个高度信息丰富的短序列重复多态性位点获得了先证者及其父母白细胞DNA的基因型，这些位点定位于着丝粒周围区域以及21号染色体的全长。这些标记的顺序先前已通过该染色体的连锁图谱和物理图谱确定。对于9个信息性标记，先证者的基因型中没有母本等位基因的贡献；此外，父本等位基因总是出现纯合性降低。这些数据表明存在21号染色体的父源单亲同二体性（pUPiD21）。我们得出结论，pUPiD21与异常表型无关，并且21号染色体上可能不存在印记基因。
