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OBJECTIVE: We describe how to set up a custom workflow for the analysis of next generation sequencing (NGS) data suitable for the diagnosis of genetic disorders and that meets the strictest standards of quality and accuracy. Our method goes from DNA extraction to data analysis with a computational in-house pipeline. The system was extensively validated using three publicly available Coriell samples, estimating accuracy, sensitivity and specificity. Multiple runs were also made to assess repeatability and reproducibility.MATERIALS AND METHODS: Three different Coriell samples were analyzed in a single run to perform coverage, sensitivity, specificity, accuracy, reproducibility and repeatability analysis. The three samples were analyzed with a custom-made oligonucleotide probe library using Nextera Rapid Capture enrichment technique and subsequently quantified using the Qubit method. Sample quality was verified using a 4200 TapeStation and sequenced on a MiSeq personal sequencer. Analysis of NGS data was then performed with a custom pipeline.RESULTS: The workflow enabled an accurate and precise analysis of NGS data that meets all the requirements of quality and accuracy required by international standards such as ISO15189 and the Association of Molecular Pathology.CONCLUSIONS: The proposed analysis/validation workflow has high assay accuracy, precision and robustness and can, therefore, be used for clinical diagnostic applications.

Background: Bardet-Biedl syndrome (BBS) is a rare inherited multisystemic disorder with autosomal recessive or complex digenic triallelic inheritance. There is currently no treatment for BBS, but some morbidities can be managed. Accurate molecular diagnosis is often crucial for the definition of appropriate patient management and for the development of a potential personalized therapy. Methods: We developed a next-generation-sequencing (NGS) protocol for the screening of the 18 most frequently mutated genes to define the genotype and clarify the mutation spectrum of a cohort of 20 BBS Italian patients. Results: We defined the causative variants in 60% of patients; four of those are novel. 33% of patients also harboured variants in additional gene/s, suggesting possible oligogenic inheritance. To explore the function of different genes, we looked for correlations between genotype and phenotype in our cohort. Hypogonadism was more frequently detected in patients with variants in BBSome proteins, while renal abnormalities in patients with variations in BBSome chaperonin genes. Conclusions: NGS is a powerful tool that can help understanding BBS patients' phenotype through the identification of mutations that could explain differences in phenotype severity and could provide insights for the development of targeted therapy. Furthermore, our results support the existence of additional BBS loci yet to be identified.

Godkänd; 2007; 20081015 (juku)

Godkänd; 2007; 20081015 (juku)