[A consensus on the standardization of the next generation sequencing process for the diagnosis of genetic diseases (1) - Procedures prior to genetic testing].

Pre-testing preparation is the basis and starting point of genetic testing. The process includes collection of clinical information, formulation of testing scheme, genetic counseling before testing, and completion of informed consent and testing authorization. To effectively identify genetic diseases in clinics can greatly improve the diagnostic rate of next generation sequencing (NGS), thereby reducing medical cost and improving clinical efficacy. The analysis of NGS results relies, to a large extent, on the understanding of genotype-phenotype correlations, therefore it is particularly important to collect and evaluate clinical phenotypes and describe them in uniform standard terms. Different types of genetic diseases or mutations may require specific testing techniques, which can yield twice the result with half the effort. Pre-testing genetic counseling can help patients and their families to understand the significance of relevant genetic testing, formulate individualized testing strategies, and lay a foundation for follow-up.

[A consensus on the standardization of the next generation sequencing process for the diagnosis of genetic diseases (2) - Sample collection, processing and detection].

With high accuracy and precision, next generation sequencing (NGS) has provided a powerful tool for clinical testing of genetic diseases. To follow a standardized experimental procedure is the prerequisite to obtain stable, reliable, and effective NGS data for the assistance of diagnosis and/or screening of genetic diseases. At a conference of genetic testing industry held in Shanghai, May 2019, physicians engaged in the diagnosis and treatment of genetic diseases, experts engaged in clinical laboratory testing of genetic diseases and experts from third-party genetic testing companies have fully discussed the standardization of NGS procedures for the testing of genetic diseases. Experts from different backgrounds have provided opinions for the operation and implementation of NGS testing procedures including sample collection, reception, preservation, library construction, sequencing and data quality control. Based on the discussion, a consensus on the standardization of the testing procedures in NGS laboratories is developed with the aim to standardize NGS testing and accelerate implementation of NGS in clinical settings across China.

[A consensus on the standardization of the next generation sequencing process for the diagnosis of genetic diseases (3) - Data analysis].

Bioinformatic analysis and variant classification are the key components of high-throughput sequencing-based genetic diagnostic approach. This consensus is part of the effort to develop a standardized process for next generation sequencing (NGS)-based test for germline mutations underlying Mendelian disorders in China. The flow-chart, common software, key parameters of bioinformatics pipeline for data processing, annotation, storage and variant classification are reviewed, which is aimed to help improving and maintaining a high-quality process and obtaining consistent outcomes for NGS-based molecular diagnosis.

[A consensus on the standardization of the next generation sequencing process for the diagnosis of genetic diseases (4) - Report interpretation and genetic counseling].

Clinical genetic testing results are compiled into a standardized report by genetic specialists and provided to clinicians and patients (Should the patient be intellectually disabled or under 18, the report will be provided to his/her parents or legal guardians). The content of genetic testing report should conform to relevant guidelines, industry standards and consensus. The decisions of clinicians will be made based on the report and clinical indications. Genetic counselors should provide post-test counseling to clinicians and patients or their authorized family members. A mechanism of follow-up visit after the genetic testing should be established with informed consent. Data should be shared by clinical institutions and genome sequencing institutions. As findings upon follow-up visit can help with further evaluation of the results, genome sequencing institutions should regularly re-analyze historical and follow-up data, and the updated results should be shared with clinical institutions. All activities involving reporting, genetic counselling, follow-up visiting, and re-analyzing should follow the relevant guidelines and regulations.

Phenotype-Driven Virtual Panel Is an Effective Method to Analyze WES Data of Neurological Disease.

Objective: Whole Exome Sequencing (WES) is an effective diagnostic method for complicated and multi-system involved rare diseases. However, annotation and analysis of the WES result, especially for single case analysis still remain a challenge. Here, we introduce a method called phenotype-driven designing "virtual panel" to simplify the procedure and assess the diagnostic rate of this method. Methods: WES was performed in samples of 30 patients, core phenotypes of probands were then extracted and inputted into an in-house software, "Mingjian" to calculate and generate associated gene list of a virtual panel. Mingjian is a self-updating genetic disease computer supportive diagnostic system that based on the databases of HPO, OMIM, HGMD. The virtual panel that generated by Mingjian system was then used to filter and annotate candidate mutations. Sanger sequencing and co-segregation analysis among the family were then used to confirm the filtered mutants. Result: We first used phenotype-driven designing "virtual panel" to analyze the WES data of a patient whose core phenotypes are ataxia, seizures, esotropia, puberty and gonadal disorders, and global developmental delay. Two mutations, c.430T > C and c.640G > C in PMM2 were identified by this method. This result was also confirmed by Sanger sequencing among the family. The same analysing method was then used in the annotation of WES data of other 29 neurological rare disease patients. The diagnostic rate was 65.52%, which is significantly higher than the diagnostic rate before. Conclusion: Phenotype-driven designing virtual panel could achieve low-cost individualized analysis. This method may decrease the time-cost of annotation, increase the diagnostic efficiency and the diagnostic rate.