Identification of novel DYNC2H1 mutations associated with short rib-polydactyly syndrome type III using next-generation panel sequencing.

Short rib-polydactyly syndrome type III (SRPS3) is a perinatal lethal skeletal disorder with polydactyly and multisystem organ abnormalities. While ultrasound of the fetus can detect skeletal abnormalities characteristic of SRPS3, the syndrome is often difficult to diagnose before birth. As SRPS3 is an autosomal recessive disorder, identification of the gene mutations involved could lead to the development of prenatal genetic testing as an accurate method of diagnosis. In this study, we describe genetic screening approaches to identify potential abnormalities associated with SRPS3. Karyotype analysis, array comparative genomic hybridization (aCGH), and next-generation panel sequencing were each performed on a fetus showing signs of the disorder, as well as on the mother and father. Karyotype and aCGH results revealed no abnormalities. However, next-generation panel sequencing identified novel mutations in the DYNC2H1 gene. The fetus was compound heterozygous for both a missense mutation c.8313A > T and a frameshift mutation c.10711_10714delTTTA in the DYNC2H1 gene, which were inherited from the mother and father, respectively. These variants were further confirmed using Sanger sequencing and have not been previously reported. Our study indicates the utility of using next-generation panel sequencing in screening for novel disease-associated mutations.

A rare case of trisomy 11q23.3-11q25 and trisomy 22q11.1-22q11.21.

Partial duplication of the long arm of chromosome 11 and the partial trisomy of 22q are uncommon karyotypic abnormalities. Here, we report the case of a 6-year-old girl who showed partial trisomy of 11q and 22q, as a result of a maternal balanced reciprocal translocation (11;22), and exhibited dysmorphic features, severe intellectual disability, brain malformations, and speech delay related to this unique chromosomal abnormality. Array comparative genomic hybridization (array CGH) revealed a gain in copy number on the long arm of chromosome 11, spanning at least 18.22 Mb. Additionally, there was a gain in copy number on the long arm of chromosome 22, spanning at least 3.46 Mb. FISH analysis using a chromosome 11 short arm telomere probe (11p14.2), a chromosome 11 long arm telomere probe (11q24.3), and a chromosome 22 long arm telomere probe (22q13.33) confirmed the origin of the marker chromosome. It has been confirmed by the State Key Laboratory of Medical Genetics of China that this is the first reported instance of the karyotype 47,XX, +der(22)t(11;22)(q23.3;q11.1)mat in the world. Our study reports an additional case that can be used to further characterize and delineate the clinical ramifications of partial trisomy of 11q and 22q.