Prenatal diagnosis of the Dandy-Walker malformation associated with partial trisomy 12p and distal 15q deletion.

Dandy-Walker malformation (DWM) is characterized by complete or partial agenesis of the cerebellar vermis, cyatic dilatation of the forth ventricle, and enlarged posterior fossa. However, the mechanism is still not completely understood up to now. In this study, we reported a rare case that a foetus with DWM showed partial trisomy 12p and distal 15q deletion. Karyotype analysis and chromosomal microarray analysis (CMA) were not always concordant with each other, and it is suggested that they should be performed for prenatal genetic diagnosis together. DWM is a rare central nervous system malformation, reported in 1/25-30,000 live births, characterized by complete or partial agenesis of the cerebellar vermis, cyatic dilatation of the forth ventricle, and enlarged posterior fossa (Kumar 2001; Klein 2003; Agrawal 2016). The neurological development of children with DWM may range from normal to severely retarded, and cause variable clinical feature. Although several efforts have been made to explore its pathogenesis, however, it is still not completely understood. During the past decade, some genetic loci, microdeletion or duplication have been reported to be associated with DWM, such as 9p trisomy, partial deletions of the long arm of chromosome 13, genes and (von Kaisenberg 2000; McCormack 2003; Grinberg 2004). In the present study, we describe a prenatal diagnosis case that a foetus with DWM on ultrasound scanning accepted genetic testing, and it revealed a microduplication of 12p13.33p11.1 and microdeletion of 15q11.2 in 750K single nucleotide polymorphism (SNP) array, while it showed 46,XX,der(8)(8pter→8q24::12p10→12qter),i(12)(p10) in karyotyping.