Somatic Reversion of a Novel IL2RG Mutation Resulting in Atypical X-Linked Combined Immunodeficiency

Mutations of the IL2RG gene, which encodes for the interleukin-2 receptor common gamma chain (γC, CD132), can lead to X-linked severe combined immunodeficiency (X-SCID) associated with a T−B+NK− phenotype as a result of dysfunctional γC-JAK3-STAT5 signaling. Lately, hypomorphic mutations of the IL2RG gene have been described causing atypical SCID with a milder phenotype. Here, we report three brothers with low-normal lymphocyte counts and susceptibility to recurrent respiratory infections and cutaneous warts. The clinical presentation combined with dysgammaglobulinemia suspected an inherited immunity disorder, which has been proven by Next Generation Sequencing as a novel c.458T > C; p.Ile153Thr IL2RG missense-mutation. Subsequent functional characterization revealed impaired T-cell proliferation, low TREC levels and a skewed TCR Vβ repertoire in all three patients. Interestingly, investigation of various subpopulations showed normal expression of CD132 but with partially impaired STAT5 phosphorylation compared to healthy controls. Additionally, we performed precise genetic analysis of subpopulations revealing spontaneous somatic reversion, predominately in lymphoid derived CD3+, CD4+ and CD8+ T cells. Our data demonstrate that the atypical SCID phenotype noticed in these three brothers is due to the combination of hypomorphic IL-2RG function and somatic reversion.

The first patient reported with X-linked severe combined immunodeficiency in Peru

Background X-linked severe combined immunodeficiency (X-SCID) is a life-threatening immune disorder caused by pathogenic mutations in the IL2RG gene. We report the first patient with genetically confirmed X-SCID in Peru. Case presentation Diagnosis was suspected before patient’s birth because of family history. At birth, blood immunophenotype was compatible with X-SCID and genetic analysis revealed a pathogenic mutation in IL2RG . Intravenous immunoglobulin and antibiotic prophylaxis were initiated until patient’s referral for an available novel treatment: gene therapy. Conclusions Family background is a key point to suspect X-SCID, allowing a timely diagnosis and treatment. X-SCID requires prompt immune reconstitution. However, HSCT is frequently not available to treat newborns in developing countries.

Computational Analysis Revealed Five Novel Mutations in Human IL2RG gene Related to X-SCID

ABSTRACTBackgroundX linked severe combined immunodeficiency (X-SCID) is a life-threatening disorder. It is due to mutation of the interleukin two receptor gamma-chain (IL2RG) gene. Nonsynonymous SNPs (nsSNPs) are the most common polymorphism, known to be deleterious or disease-causing variations because they alter protein sequence, structure, and function. Objective: is to reveal the effect of harmful SNPs in the function and structure of IL2RG protein.MethodData on IL2RG was investigated from dbSNP/NCBI database. Prediction of damaging effect was done using sift, polyphen, provean and SNAP2.more software were used for more analysis: phd-snp, and and go, Pmut, Imutant.modeling was done using chimera and project hope. Gene interaction was done by gene mania.3UTR prediction was done using polymiRTS software.ResultThe in-silico prediction identified 1479 SNPs within IL2RG gene out of which 253 were coding SNPs, 50 took place in the miRNA 3 UTR, 21 occurred in 5 UTR region and 921 occurred in intronic regions. a total of 12 missense nsSNPs were found to be damaging by both a sequence homology-based tool (SIFT) and a structural homology-based method (PolyPhen), Five of them were novel; rs1322436793(G305R), rs1064794027(C182Y), rs111033620(G114D), rs193922347 (Y105C) and rs1293196743(Y91C), Two SNPs(Rs144075871 and rs191726889) out of 50 in the 3UTR region were predicted to disrupt miRNAs binding sites and affect the gene expression.ConclusionsComputational analysis of SNPs has become a very valuable tool in order to discriminate neutral SNPs from damaging SNPs. This study revealed 5 novel nsSNPs in the IL2RG gene by using different software and 21 SNPs in 3UTR. These SNPs could be considered as important candidates in causing diseases related to IL2RG mutation and could be used as diagnostic markers.

Stem cell-derived clade F AAVs mediate high-efficiency homologous recombination-based genome editing

The precise correction of genetic mutations at the nucleotide level is an attractive permanent therapeutic strategy for human disease. However, despite significant progress, challenges to efficient and accurate genome editing persist. Here, we report a genome editing platform based upon a class of hematopoietic stem cell (HSC)-derived clade F adeno-associated virus (AAV), which does not require prior nuclease-mediated DNA breaks and functions exclusively through BRCA2-dependent homologous recombination. Genome editing is guided by complementary homology arms and is highly accurate and seamless, with no evidence of on-target mutations, including insertion/deletions or inclusion of AAV inverted terminal repeats. Efficient genome editing was demonstrated at different loci within the human genome, including a safe harbor locus, AAVS1, and the therapeutically relevant IL2RG gene, and at the murine Rosa26 locus. HSC-derived AAV vector (AAVHSC)-mediated genome editing was robust in primary human cells, including CD34+cells, adult liver, hepatic endothelial cells, and myocytes. Importantly, high-efficiency gene editing was achieved in vivo upon a single i.v. injection of AAVHSC editing vectors in mice. Thus, clade F AAV-mediated genome editing represents a promising, highly efficient, precise, single-component approach that enables the development of therapeutic in vivo genome editing for the treatment of a multitude of human gene-based diseases.