Journal Article

Germline CARD11 Mutation in a Patient with Severe Congenital B Cell Lymphocytosis

Jennings, Chester D., Dalgard, Clifton L., Stinson, Jeffrey R., Wang, Wei, Moscow, Jeffrey A., Sindiri, Sivasish, Su, Helen C., Kardava, Lela, Moir, Susan, Snow, Andrew L., Khan, Javed, Brohl, Andrew S., Sukumar, Gauthaman, Badgett, Thomas

2015

Overview

Purpose Activating germline mutations in CARD11 have recently been linked to a rare genetic disorder associated with congenital B cell lymphocytosis. We describe a patient with a similar clinical phenotype who had a de novo germline G123D CARD11 mutation. Methods Whole exome sequencing was performed on DNA from the patient and his biological parents. Laboratory studies examined characteristics of the patient’s B and T lymphocytes. A CARD11 cDNA containing the mutation was transfected into a lymphocyte cell line to gain an understanding of its function. RNA sequencing was performed on samples from the patient and from patients with alternate germline CARD11 mutations and differential gene expression analysis was performed. Results The patient had a decade-long history of severe polyclonal B lymphocytosis in the 20,000–90,000 lymphocytes/mm 3 range, which was markedly exacerbated by EBV infection and splenectomy at different times. He had a heterozygous germline CARD11 mutation causing a G123D amino acid substitution, which was demonstrated to induce NF-κB activation in unstimulated lymphocytes. In contrast to previous patients with CARD11 mutations, this patient’s B cells exhibited higher expression of several cell cycle progression genes, as well as enhanced proliferation and improved survival following B cell receptor stimulation. Conclusions This is the third reported germline and first de novo CARD11 mutation shown to cause congenital B cell lymphocytosis. The mutation was associated with a dramatically greater lymphocytosis than in previously described cases, disproportionate to the level of constitutive NF-κB activation. However, comparative review of the patient’s clinical history, combined with additional genomic and functional analyses, underscore other important variables that may affect pathophysiology or regulate mutant CARD11 function in B cell proliferation and disease. We now refer to these patients as having BENTA disease ( B cell E xpansion with N F-κB and T cell A nergy).

• Publisher: Springer US,Springer Nature B.V
• Subject: Amino Acid Substitution / Apoptosis - genetics / B-Lymphocytes - immunology / B-Lymphocytes - metabolism / B-Lymphocytes - pathology / Base Sequence / Biomedical and Life Sciences / Biomedicine / CARD Signaling Adaptor Proteins - chemistry / CARD Signaling Adaptor Proteins - genetics / Cell Proliferation - genetics / Child / DNA - genetics / Epstein-Barr virus / Gene Expression Profiling / Germ-Line Mutation / Guanylate Cyclase - chemistry / Guanylate Cyclase - genetics / Humans / Immunology / Infectious Diseases / Internal Medicine / Lymphocyte Activation - genetics / Lymphocytosis - congenital / Lymphocytosis - genetics / Lymphocytosis - immunology / Male / Medical Microbiology / Mutant Proteins - chemistry / Mutant Proteins - genetics / Mutation, Missense / NF-kappa B - metabolism / Original Research