[Simple virilizing forms of congenital adrenal hyperplasia: adaptation and prospective validation of the molecular screening]. / Formas virilizantes simples de hiperplasia suprarrenal congénita: adaptación y validación prospectiva del cribado molecular de diagnóstico.

BACKGROUND AND OBJECTIVE: Congenital Adrenal Hyperplasia (CAH) is not an infrequent genetic disorder for which mutation-based analysis for CYP21A2 gene is a useful tool. Contrarily to salt-wasting forms the basic mutation screening accounts only for 83% of simple virilising (SV) phenotypes. Rare alleles with a local distribution not included in the basic panel may reduce its diagnostic accuracy. Our aim is to explore underlying prevalent mutations among our partially characterised SV forms and to evaluate their potential impact in the mutation screening. PATIENTS AND METHODS: Preliminary study: CYP21A2 gene sequencing in 13 SV patients partially characterised. Retrospective targeted study: 2,097 DNA samples (561 patients) were re-analysed for p.R426H mutation. Prospective targeted study: incorporation of the p.R426H mutation to the initial exploration of CAH in 1,041 DNA samples to validate this extended screening. RESULTS: p.R426H mutation was detected in five patients in the preliminary analysis and in ten more during targeted studies. A frequency for this mutation was 0.71% in the whole group and 7.14% in SV forms. Associated haplotypes were identical thus suggesting a preferential dissemination. The observed phenotypes correlated and confirmed the moderate-to-severe effect on the enzymatic activity. CONCLUSIONS: Our data relative to allelic frequency of the p.R426H mutation and its strong association to SV forms justify the incorporation of the p.R426H mutation into the basic screening panel because of the significant improvement in the initial characterization of affected patients, especially among those with SV forms. Two new cases detected remark the usefulness of this novel approach.

Development and validation of a next-generation sequencing panel for clinical pharmacogenetics.

The rapid clinical implementation of next generation sequencing techniques is  due to its ability to sequence a large number of genetic regions at lower costs  than conventional techniques. However, its use in the field of pharmacogenetics  is still very limited. OBJECTIVE: Design, development, implementation and validation of a clinical  pharmacogenetics next-generation sequencing panel. METHOD: We developed a panel of hybrid capture probes (SureSelect®) for the  analysis of the genetic regions of clinical interest collected by literature search  and using Illumina HiSeq 1500® sequencing platform. We developed a  bioinformatic algorithm for variant annotation, haplotype inference and  determination of structural variants in the genes of interest. The results obtained were validated with Coriell® reference material from the pharmacogenetic  repositories. RESULTS: The developed panel allows the study of a total of 12,794 regions comprised in 389 genes. Validation results showed a sensitivity greater  than 99% for single nucleotide variants and small INDELs. Haplotype imputation was consistent with the consensus results in the characterized  reference materials. Furthermore, the developed tool was able to correctly  identify different types of CYP2D6 copy number variations as well as a wide  variety of HLA-B alleles. CONCLUSIONS: This technology represents an appropriate alternative for its  clinical use with advantages over conventional techniques in its throughput and  complex gene study capabilities (CYP2D6, HLA-B).

La rápida implantación clínica de las técnicas de secuenciación masiva en  paralelo se debe a su capacidad para secuenciar un gran número de regiones  genéticas con un coste menor a las técnicas convencionales. Sin embargo, su  uso en el ámbito de la farmacogenética es, todavía, muy escaso.Objetivo: Diseño, desarrollo, implementación y validación de un panel de  secuenciación masiva en paralelo de farmacogenética orientado a la práctica  clínica.Método: Se desarrolló un panel de sondas de captura híbrida (SureSelect ®)  para el análisis de las regiones genéticas de interés clínico recopiladas mediante  búsqueda bibliográfica. Se empleó la plataforma de secuenciación Illumina HiSeq 1500®. Se desarrolló un algoritmo de análisis bioinformático para la anotación  de variantes puntuales, inferencia de haplotipos y determinación de variantes  estructurales en los genes de interés. Los resultados obtenidos se validaron con  materiales de referencia Coriell® de los repositorios de farmacogenética.Resultados: El panel desarrollado permite el estudio de un total de 12.794  regiones comprendidas en 389 genes. Los resultados de validación mostraron  una sensibilidad superior al 99% para variantes puntuales e inserciones y  deleciones pequeñas. La imputación de haplotipos fue coherente con los  resultados consenso de los materiales de referencia caracterizados. Además, la  herramienta desarrollada pudo identificar correctamente diferentes tipos de  variaciones de número de copias de CYP2D6, así como una gran variedad de  alelos de HLA-B.Conclusiones: Esta tecnología representa una alternativa adecuada para su  empleo asistencial con ventajas frente a las técnicas convencionales en su  rendimiento de producción y sus capacidades de estudio de genes complejos  (CYP2D6, HLA-B).