Program in Human Genetics, Johns Hopkins School of Medicine, Baltimore, MD, USA.
Eur J Hum Genet. 2011 Feb;19(2):235-8. doi: 10.1038/ejhg.2010.150. Epub 2010 Sep 8.
Partial monosomy 21 was recently segregated into three regions associated with variable clinical severity. We describe 10 new patients, all examined by single nucleotide polymorphism (SNP) genotyping and G-banded karyotyping. Cohort A consisted of three patients seen in our medical genetics clinics with partial chromosome 21 monosomies. In two of these patients having terminal deletions (21q22.2-ter and 21q22.3-ter), the breakpoints differed by at least 812 Kb of sequence, containing seven RefSeq genes. A third patient had an interstitial hemizygous loss of 16.4 Mb (21q21.1-q22.11). All three patients had relatively mild phenotypes. Cohort B consisted of seven patients with partial chromosome 21 monosomies who had a greater number of dysmorphic features and some major malformations; SNP genotypes were obtained from the Coriell Genetic Cell Repository. We also collected data on partial monsomy 21 cases from the DECIPHER database. This report of 10 new cases of 21q deletion and review of a total of 36 confirms that deletion of the terminal region is associated with a mild phenotype, but suggests that deletion of regions 1 and 2 is compatible with life and have a variable phenotype perhaps relating more to other genetic and environmental variables than to genes in the interval.
部分 21 号染色体单体性最近被分为三个与不同临床严重程度相关的区域。我们描述了 10 名新患者，均通过单核苷酸多态性 (SNP) 基因分型和 G 带核型分析进行检查。队列 A 由我们医学遗传学诊所的三名患有部分 21 号染色体单体性的患者组成。在这两名患者中，两名患者的末端缺失（21q22.2-ter 和 21q22.3-ter）之间的断点相差至少 812 Kb 的序列，包含七个 RefSeq 基因。第三名患者存在 16.4 Mb 的半合子缺失（21q21.1-q22.11）。这三名患者的表型均相对较轻。队列 B 由七名患有部分 21 号染色体单体性的患者组成，这些患者有更多的畸形特征和一些主要的畸形；从 Coriell 遗传细胞库获得了 SNP 基因型。我们还从 DECIPHER 数据库收集了部分 21 号单体性病例的数据。这 10 例新的 21q 缺失病例报告和对总共 36 例病例的回顾表明，末端区域的缺失与轻度表型相关，但提示 1 区和 2 区的缺失与生活兼容，且表型存在差异，这可能与间隔内的基因无关，而与其他遗传和环境变量有关。
