Gopal V V, Roop H, Carpenter N J
H.A. Chapman Institute of Medical Genetics, Tulsa, Oklahoma 74135.
Am J Med Sci. 1995 Apr;309(4):208-12. doi: 10.1097/00000441-199504000-00004.
Contiguous gene syndromes are characterized by deletions or duplications of specific chromosomal segments involving clusters of single genes. Although these syndromes are associated with distinct clinical phenotypes, these features are difficult to distinguish in the newborn and early childhood periods. In such cases, demonstration of chromosomal involvement through cytogenetic studies is of vital importance in arriving at an accurate diagnosis. In this article results of microdeletion analysis of 31 cases comprising 16 cases of Prader-Willi syndrome, 3 of Angelman syndrome, 7 of Miller-Dieker syndrome, and 5 of DiGeorge syndrome are reported. All patients were studied with both high-resolution chromosome analysis and fluorescence in situ hybridization. In the majority of cases there is 100% concordance between the two techniques. However, in one patient suspected of having DiGeorge syndrome with a normal karyotype at the 750 band level, fluorescence in situ hybridization identified a deletion within the critical region. Without fluorescence in situ hybridization studies on this patient, it would not have been possible to confirm the diagnosis of DiGeorge syndrome cytogenetically. Based on these results and other studies reported in the literature, it is recommended that all suspected cases of microdeletion syndromes should be studied using fluorescence in situ hybridization, irrespective of high-resolution chromosome results. However, because of the difficulties associated with clinical diagnosis of these syndromes, fluorescence in situ hybridization should not replace standard chromosome analysis.
相邻基因综合征的特征是特定染色体片段的缺失或重复，这些片段涉及单个基因簇。尽管这些综合征与独特的临床表型相关，但在新生儿期和幼儿期很难区分这些特征。在这种情况下，通过细胞遗传学研究证明染色体受累对于准确诊断至关重要。本文报道了对31例患者的微缺失分析结果，其中包括16例普拉德-威利综合征、3例天使综合征、7例米勒-迪克尔综合征和5例迪乔治综合征。所有患者均接受了高分辨率染色体分析和荧光原位杂交研究。在大多数情况下，两种技术的结果100%一致。然而，在1例疑似迪乔治综合征且在750条带水平核型正常的患者中，荧光原位杂交在关键区域发现了一个缺失。如果没有对该患者进行荧光原位杂交研究，就不可能通过细胞遗传学确诊迪乔治综合征。基于这些结果以及文献中报道的其他研究，建议对所有疑似微缺失综合征病例都应使用荧光原位杂交进行研究，无论高分辨率染色体结果如何。然而，由于这些综合征临床诊断存在困难，荧光原位杂交不应取代标准染色体分析。
