LPS-responsive beige-like anchor (LRBA) gene mutation in a family with inflammatory bowel disease and combined immunodeficiency.

BACKGROUND Clinical immunology has traditionally relied on accurate phenotyping of the patient's immune dysfunction for the identification of a candidate gene or genes for sequencing and molecular confirmation. Although this is also true for other branches of medicine, the marked variability in immune-related phenotypes and the highly complex network of molecules that confer normal host immunity are challenges that clinical immunologists often face in their quest to establish a specific genetic diagnosis. OBJECTIVE We sought to identify the underlying genetic cause in a consanguineous family with chronic inflammatory bowel disease-like disorder and combined immunodeficiency. METHODS We performed exome sequencing followed by autozygome filtration. RESULTS A truncating mutation in LPS-responsive beige-like anchor (LRBA), which abolished protein expression, was identified as the most likely candidate variant in this family. CONCLUSION The combined exome sequencing and autozygosity mapping approach is a powerful tool in the study of atypical immune dysfunctions. We identify LRBA as a novel immunodeficiency candidate gene the precise role of which in the immune system requires future studies.