Teebi A S, Gibson L, McGrath J, Meyn M S, Breg W R, Yang-Feng T L
Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510.
Am J Med Genet. 1993 May 15;46(3):288-92. doi: 10.1002/ajmg.1320460310.
We report on 2 girls with terminal deletion of the short arm of chromosome 9 with concurrent duplication unrecognizable by routine chromosome studies. The phenotype of the patients was not specifically suggestive of the 9p-syndrome in the absence of trigonocephaly and long philtrum as cardinal manifestations. In addition to psychomotor retardation, their manifestations were mild and include upward slant of palpebral fissures and dolichomesophalangy which are characteristic of del(9p). Chromosome abnormalities were de novo in both cases. The two rearranged chromosomes 9 exhibit similar G-banding patterns and suggested the possible duplication of distal 7p. Fluorescence in situ hybridization (FISH) with a chromosome-7 specific library probe indeed identified that one derivative chromosome 9 was the result of a translocation between chromosomes 7 and 9 [der(9)t(7;9)(p15.3;p24] but failed to detect a signal on the other derivative 9. In the second case, the concurrent abnormality was an inverted duplication of proximal 9p and deletion of distal 9p [inv dup(9)(p13-->p22::p22-->qter)] confirmed by FISH using a chromosome 9 specific library probe. FISH clearly identified the origin of these 2 abnormal chromosomes 9 and provided crucial information for clinical evaluation. We emphasize the importance of utilizing updated cytogenetic and molecular techniques in the precise delineation of subtle or complex abnormalities where there are no useful phenotypic clues.
我们报告了2名患有9号染色体短臂末端缺失且伴有常规染色体研究无法识别的并发重复的女孩。在没有作为主要表现的三角头畸形和长人中的情况下,患者的表型并无9p综合征的特异性提示。除精神运动发育迟缓外,她们的表现较轻,包括睑裂上斜和中指细长,这些是9p缺失的特征。两例染色体异常均为新发。两条重排的9号染色体显示出相似的G带模式,并提示可能存在7p远端重复。用染色体7特异性文库探针进行荧光原位杂交(FISH)确实鉴定出一条衍生的9号染色体是7号和9号染色体之间易位的结果[der(9)t(7;9)(p15.3;p24)],但在另一条衍生的9号染色体上未检测到信号。在第二例中,并发异常是9号染色体近端的倒位重复和远端9p的缺失[inv dup(9)(p13-->p22::p22-->qter)],通过使用染色体9特异性文库探针的FISH得以证实。FISH清楚地确定了这两条异常9号染色体的起源,并为临床评估提供了关键信息。我们强调在没有有用的表型线索时,利用更新的细胞遗传学和分子技术精确描绘细微或复杂异常的重要性。