Exome and genome sequencing for inborn errors of immunity.
The advent of next generation sequencing (NGS) in 2010 has transformed medicine, particularly the growing field of inborn errors of immunity. NGS has facilitated the discovery of novel disease causing genes and the genetic diagnosis of patients with monogenic inborn errors of immunity. Whole exome sequencing (WES) is presently the most cost effective approach for research and diagnostics, although whole genome sequencing offers several advantages. The scientific or diagnostic challenge consists in selecting 1 or 2 candidate variants among thousands of NGS calls. Variant and gene level computational methods, as well as immunologic hypotheses, can help narrow down this genome wide search. The key to success is a well informed genetic hypothesis on 3 key aspects: mode of inheritance, clinical penetrance, and genetic heterogeneity of the condition. This determines the search strategy and selection criteria for candidate alleles. Subsequent functional validation of the disease causing effect of the candidate variant is critical. Even the most up to date dry lab cannot clinch this validation without a seasoned wet lab. The multifariousness of variations entails an experimental rigor even greater than traditional Sanger sequencing based approaches in order not to assign a condition to an irrelevant variant. Finding the needle in the haystack takes patience, prudence, and discernment.
The Journal of allergy and clinical immunology