Background: Gaining a correct genetic diagnosis for patients with adrenal insufficiency is important not only to enable genetic counselling within their families, but also for correct treatment and long term management. Adrenal insufficiency is genetically heterogeneous and the long-term sequelae for many of the gene defects, including the progression of the disease and involvement of other tissues, is unknown. Next-generation sequencing (NGS) technologies allow parallel sequence and CNV analysis of multiple genes simultaneously and are therefore ideal to screen genetically heterogeneous disorders.
Methods: We have designed a high-throughput custom Haloplex NGS panel to study 150 known and candidate genes for adrenal insufficiency. As a preliminary study we processed 28 patients without a diagnosis for their adrenal insufficiency. Data analysis was performed using two pipelines, Agilent SureCall Software and Ingenuity Variant Analysis.
Results: A rapid molecular diagnosis was obtained for 11/28 patients including new and previously reported mutations in HSD3B2 (one patient, homozygous p.R335*), MC2R (two patients, homozygous for p.N81fs*3 and p.F235fs*7), NR0B1 (two patients, hemizygous for p.S431fs*6 and p.L436R), ABCD1 (two patients hemizygous for p.Q472fs*83 and p.A262T), STAR (one patient, compound heterozygous for p.G221S and p.G201D), CYP11A1 (one patient, compound heterozygous for p.R439* and p.E314K), NNT (one patient, compound heterozygous for p.G236V and p.P437L), and POMC (compound heterozygous for p.R145C and a regulatory region variant c.-11C>A). Deleterious, single heterozygous changes were discovered in a further 6 patients in POR, AAAS, STAR, AIRE, and TXNRD2 hinting at a genetic diagnosis for these individuals too.
Conclusion: The application of targeted enrichment and NGS can be utilised to aid in the rapid identification of novel and known pathogenic mutations in adrenal insufficiency whilst avoiding the incidental findings associated with whole exome or whole genome sequencing.