Study On Chromosomal Abnormal Of Dandy-Walker Syndrome By Array-CGH

ObjectiveDandy-Walker syndrome (DWS) is a kind of congenital diseases of the nervous system, and is the developmental anomalies due to the cerebellum malformations and lateral holes in the fourth ventricle closure, cause the fourth ventricle cystic expand and secondary obstructive hydrocephalus and prognosis. At present, no particular gene was found to relate to DWS, but many chromosome abnormality reports of DWS have been presented. It almost covers all 24 human chromosomes. Therefore, it's very particularly important to prenatal diagnosis on DWS with molecular genetics and cytogenetic methods. Now genetic methods to test DWS in most medical research institutions are mainly karyotype analysis, fluorescence in situ hybridization (FISH). They have found that some cases with trisomy, partial trisomy, and chromosomal microdeletion and so on. This study base on karyotype analysis, FISH and M-FISH, but also extract DNA from DWS and do microarray, the latest molecular method to detect unbalance chromosomal abnormalities and specific gene deletion and find the convenient and accurate prenatal diagnosis method and genetic etiology.Methods(1) Cell culture, G-banding and Karyotype:CHANG's culture medium added into blood, culture 2 days in 37℃oven, then add cosmid and cultured another day. Harvest cells the other day and fix them, drop slides, dry 24 hours then G-banding, do karyotype.(2) Fluorescence In Situ Hybridization (FISH):Add RBC cracking solution and put in 37℃water-bath 20 minutes, then fix cells with acid solution three times, drop slides and dry, then add probes and hybridization.(3) Array-CGH:Abstraction DNA from blood, amnio and POC. Both sample and reference DNA were sonicated by microtip. Sample DNA labeled by Cy3。Control DNA labeled by Cy5。Put the mixture in 98℃PCR for 10 minutes to denature。Then put on ice-water to freeze for 1 minute, add Klenow mixture。Then put in 37℃PCR for 2 hours, add 10.5M EDTA to end Klenow reaction. Put every sample in dark room for 10 minutes, then spin down for 10 minutes, wash with 80%cold alcohol, and dry. Measure DNA again, put both sample and control DNA togather, put in 95℃5minutes to denature, then put in 42℃hybridiziong for 16-20 hours。Wash arrays and scan, analysis database by Nimblescan v2。ResultNo micro deletion or micro duplication was found from any of these 24 cases. Two amnio cases were considered aneuploidy one is trisomy 13 and the other is 47,XXX. One POC case is triploidy (69,XXX); one amnio case is MVA syndrome(Mosaic Variegated Aneuploidy Syndrome); one newborn blood case is multiple balanced translocation involving chromosome 3,4,6,8,9.Conclusions5 cases were detected to have abnormal chromosomes from our 24 cases, which positive rate is about 20.83%. This study demonstrates that some DWS cases caused by chromosomal number abnormal; DWS doesn't relate to specific gene aberration; and array-CGH can detect congenital malformation caused by gene copies aberration quickly and accurately. It's the latest reliable accurate diagnosis technology and advanced detection for better antenatal diagnosis of fetal chromosome abnormality.