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Common Variable Immunodeficiency and Neurodevelopmental Delay Due to a 13Mb Deletion on Chromosome 4 Including the NFKB1 Gene: A Case Report.

ABSTRACT: Syndromic immunodeficiencies are a heterogeneous group of inborn errors of immunity that can affect the development of non-immune organs and systems. The genetic basis of these immunodeficiencies is highly diverse, ranging from monogenic defects to large chromosomal aberrations. Antibody deficiency is the most prevalent immunological abnormality in patients with syndromic immunodeficiencies caused by chromosomal rearrangements, and usually manifests as a common variable immunodeficiency (CVID)-like phenotype. Here we describe a patient with a complex phenotype, including neurodevelopmental delay, dysmorphic features, malformations, and CVID (hypogammaglobulinemia, reduced pre-switch and switch memory B cells, and impaired vaccine response). Microarray-based comparative genomic hybridization (aCGH) revealed a 13-Mb deletion on chromosome 4q22.2-q24 involving 53 genes, some of which were related to the developmental manifestations in our patient. Although initially none of the affected genes could be linked to his CVID phenotype, subsequent reanalysis identified NFKB1 haploinsufficiency as the cause. This study underscores the value of periodic reanalysis of unsolved genetic studies performed with high-throughput technologies (eg, next-generation sequencing and aCGH). This is important because of the ongoing incorporation of new data establishing the relationship between genes and diseases. In the present case, NFKB1 had not been associated with human disease at the time aCGH was performed. Eight years later, reanalysis of the genes included in the chromosome 4 deletion enabled us to identify NFKB1 haploinsufficiency as the genetic cause of our patient's CVID. In the future, other genes included in the deletion may be linked to human disease, allowing us to better define the molecular basis of our patient's complex clinical phenotype.

SUBMITTER: Franco-Jarava C

PROVIDER: S-EPMC9247144 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:In common variable immunodeficiency (CVID), heterozygous damaging NFKB1 variants represent the most frequent monogenic cause. NFKB1 encodes the precursor p105, which undergoes proteasomal processing to generate the mature NF-κB transcription factor subunit p50. The majority of NFKB1 sequence changes comprises missense variants of uncertain significance (VUS), each requiring functional evaluation to assess causality, particularly in families with multiple affected members presenting with different phenotypes. In four affected members of a German family, all diagnosed with CVID, we identified a previously uncharacterized heterozygous NFKB1 missense variant (c.1049A>G; p.Tyr350Cys). The clinical phenotypes varied markedly regarding onset, frequency and severity of infections. Consistent immunologic findings were hypogammaglobulinemia with normal specific antibody response to protein- and polysaccharide-based vaccinations, reduced switched memory B cells and decreased lymphocyte proliferation upon stimulation with the B cell mitogen SAC. To assess the pathogenicity of the NFKB1 missense variant, we employed immunophenotyping and functional analyses in a routine in vitro cell culture model. Following site-directed mutagenesis to introduce the variant into overexpression vectors encoding EGFP-fused p105 or p50, we analyzed transiently transfected HEK293T cells by confocal imaging and Western blotting. The cytoplasmic p105-Tyr350Cys precursor gained only weak expression levels indicating accelerated decay. The missense change disabled processing of the precursor to prevent the generation of mutant p50. Unlike the wildtype p50, the overexpressed mutant p50-Tyr350Cys was also not sustainable and showed a conspicuous subnuclear mislocalization with accumulation in dense aggregates instead of a homogenous distribution. Electrophoretic mobility shift assays, fluorescence-based reporter gene analyses and co-transfection experiments however demonstrated, that the DNA-binding activity of p50-Tyr350Cys and the interaction with RelA(p65), IκBα and wildtype p50 were preserved. Mutation carriers had reduced p105 and p50 levels, indicating insufficient protein amounts as the most likely primary defect. In conclusion, the missense variant c.1049A>G caused a detrimental defect, preventing the persistent expression of both, the p105-Tyr350Cys precursor and the mature p50-Tyr350Cys. The variable clinical phenotypes among affected family members sharing an identical pathogenic NFKB1 variant support a disease mechanism provoked by a p105/p50 (haplo)insufficient condition.

Project description:Background:Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency and has a broad spectrum of clinical manifestations. Among non-infectious complications, an increased incidence of malignancies may have a special relevance for survival, but little is known about treatment efficacy on malignant complications. Methods:This was a monocenter retrospective study on CVID patients, designed to provide preliminary data for the investigation of the possible link between therapeutic delay and tumor incidence. Results:A total of 67 CVID subjects were included. The median diagnostic delay was 7.5 years (range: 0-63 years), and the median therapeutic delay was 8.5 years (range: 0-67 years). Malignancies were diagnosed in 18 (27%) patients. Eight out of 18 (44%) patients with a malignancy had lymphoma. Patients who developed a malignancy showed a longer therapeutic delay in comparison to patients with no malignancy, although no statistical significance was achieved (11 years vs 8 years, respectively, p?=?0.424). We observed a lower frequency of malignancy in CVID patients with reduced therapeutic delay compared with patients with therapeutic delay???10 years. With a therapeutic delay of?>?1 year, 74% had no tumor, and 25% had a tumor; with a therapeutic delay of?>?10 years, 65% had no tumor and 35% had a malignancy. Among patients who had no malignancy, 64% had a therapeutic delay of?<?10 years, and 36% had a therapeutic delay of???10 years. Among patients with malignancy, 47% of subjects had a therapeutic delay?<?10 years, and 53% a therapeutic delay???10 years. Conclusions:The observation of clinical characteristics of our patients with CVID may suggest that an early institution of IgG replacement therapy could be of benefit for the prevention of malignant complications.Name of the registry: Comitato Etico Regionale delle Marche. Trial registration number: 1505. Date of registration: 27/10/2016, Retrospectively registered URL of trial registry record: http://www.ospedaliriuniti.marche.it/portale/archivio13_cerm-ancona_0_446_1.html. The trial was not registered before the first participant was enrolled.

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Common Variable Immunodeficiency and Neurodevelopmental Delay Due to a 13Mb Deletion on Chromosome 4 Including the NFKB1 Gene: A Case Report.

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