Astute Clinician Report: A Novel 10 bp Frameshift Deletion in Exon 2 of ICOS Causes a Combined Immunodeficiency Associated with an Enteritis and Hepatitis.

ABSTRACT: ICOS encodes the Inducible T-cell Co-Stimulator (ICOS). Deficiency of this receptor in humans causes a common variable immunodeficiency (CVID) characterised by an absence of class-switched memory B cells and hypogammaglobulinemia. Three pathogenic mutations in ICOS have been described to date in a total of 13 cases. Here we report a novel homozygous 10 base pair frameshift deletion in exon 2 discovered by whole exome sequencing of two siblings from a family of Pakistani origin. Both patients presented in early childhood with diarrhea, colitis and transaminitis and one showed defective handling of human herpesvirus 6. Activated patient CD3(+)CD4(+) T lymphocytes demonstrated a complete absence of ICOS expression and, consistent with previous reports, we detected a reduction in circulating T

SUBMITTER: Robertson N 

PROVIDER: S-EPMC4628077 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature