A family history of SCID and unrevealing WES: An approach to management and guidance of patients.

Severe Combined Immunodeficiency (SCID) is a genetically heterogeneous group of disorders characterized by severe T cell lymphopenia and defective T and B cell function. Without prompt diagnosis and early intervention, patients with SCID typically die from infection within the first year of life. Advances in molecular genetics have led to rapid and efficient diagnosis of SCID cases, particularly when paired with newborn screening. However, some cases remain unsolved, and this is of particular relevance to families that plan to have more children. Here we report a patient who died from complications of SCID in whom whole exome sequencing failed to reveal a candidate variant. We describe how Sanger sequencing of parents was used to study the genomic regions that were poorly covered by WES, and how immune phenotyping results were used in the setting of genetic counseling.