Loss of B Cells in Patients with Heterozygous Mutations in IKAROS.

BACKGROUND: Common variable immunodeficiency (CVID) is characterized by late-onset hypogammaglobulinemia in the absence of predisposing factors. The genetic cause is unknown in the majority of cases, and less than 10% of patients have a family history of the disease. Most patients have normal numbers of B cells but lack plasma cells. METHODS: We used whole-exome sequencing and array-based comparative genomic hybridization to evaluate a subset of patients with CVID and low B-cell numbers. Mutant proteins were analyzed for DNA binding with the use of an electrophoretic mobility-shift assay (EMSA) and confocal microscopy. Flow cytometry was used to analyze peripheral-blood lymphocytes and bone marrow aspirates. RESULTS: Six different heterozygous mutations in IKZF1, the gene encoding the transcription factor IKAROS, were identified in 29 persons from six families. In two families, the mutation was a de novo event in the proband. All the mutations, four amino acid substitutions, an intragenic deletion, and a 4.7-Mb multigene deletion involved the DNA-binding domain of IKAROS. The proteins bearing missense mutations failed to bind target DNA sequences on EMSA and confocal microscopy; however, they did not inhibit the binding of wild-type IKAROS. Studies in family members showed progressive loss of B cells and serum immunoglobulins. Bone marrow aspirates in two patients had markedly decreased early B-cell precursors, but plasma cells were present. Acute lymphoblastic leukemia developed in 2 of the 29 patients. CONCLUSIONS: Heterozygous mutations in the transcription factor IKAROS caused an autosomal dominant form of CVID that is associated with a striking decrease in B-cell numbers. (Funded by the National Institutes of Health and others.).

Eosinophilic esophagitis as paraneoplastic syndrome in a patient with ganglioneuroblastoma.

A 16-month-old boy presented with failure to thrive despite sufficient caloric intake, hypersalivation, abdominal pain, chronic diarrhea and blepharitis. An eosinophilic esophagitis (EoE) was diagnosed by esophageal biopsy. Dietary restrictions and topical steroid treatment lead to no improvement. Further diagnostic work-up revealed an intrathoracal, paraspinal ganglioneuroblastoma. After operative extirpation of the tumour, all initial symptoms resolved. An esophageal control biopsy 4 weeks after tumour resection was normal. This is the first report of eosinophilic esophagitis as part of a paraneoplastic syndrome in a patient with a malignant disease other than a carcinoma.