Hidden Mutations in CdLS - Limitations of Sanger Sequencing in Molecular Diagnostics
Résumé
Cornelia de Lange syndrome (CdLS) is a well characterized developmental disorder. The genetic cause of CdLS is a mutation in one of five associated genes (NIPBL, SMC1A, SMC3, RAD21 and HDAC8) accounting for about 70 % of cases. To improve our current molecular diagnostic and to analyze some of CdLS candidate genes we developed and established a gene panel approach. Because recent data indicate a high frequency of mosaic NIPBL mutations that were not detected by conventional sequencing approaches of blood DNA, we started to collected buccal mucosa samples of our patients that were negative for mutations in the known CdLS genes. Here we report the identification of three mosaic NIPBL mutations by our high-coverage gene panel sequencing approach that were undetected by classical Sanger sequencing analysis of buccal mucosa DNA. All mutations were confirmed by the use of highly sensitive SNaPshot fragment analysis using DNA from buccal mucosa, urine and fibroblast samples. In blood samples we could not detect the respective mutation. Finally, in fibroblast samples from all three patients, Sanger sequencing could identify all the mutations. Thus, our study highlights the need for highly sensitive technologies in molecular diagnostic of CdLS to improve genetic diagnosis and counseling of patients and their families. This article is protected by copyright. All rights reserved.