Project description:Autosomal recessive (AR) complete interferon-? receptor 1 (IFN-?R1) deficiency, also known as one genetic etiology of Mendelian susceptibility to mycobacterial disease (MSMD), is a life-threatening congenital disease leading to premature death. Affected patients present a pathognomonic predisposition to recurrent and severe infections with environmental mycobacteria or the Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine. Current therapeutic options are limited to antibiotic treatment and hematopoietic stem cell transplantation, however with poor outcome. Given the clinical success of gene therapy, we introduce the first lentiviral-based gene therapy approach to restore expression and function of the human IFN-?R-downstream signaling cascade. In our study, we developed lentiviral vectors constitutively expressing the human IFN-?R1 and demonstrate stable transgene expression without interference with cell viability and proliferation in transduced human hematopoietic cells. Using an IFN-?R1-deficient HeLa cell model, we show stable receptor reconstitution and restored IFN-?R1 signaling without adverse effect on cell functionality. Transduction of both SV40-immortalized and primary fibroblasts derived from IFN-?R1-deficient MSMD patients was able to recover IFN-?R1 expression and restore type II IFN signaling upon stimulation with IFN-?. In summary, we highlight lentiviral vectors to correct the IFN-? mediated immunity and present the first gene therapy approach for patients suffering from AR complete IFN-?R1 deficiency.
Project description:We studied a case with suspected PIK3CD deficiency with a homozygous mutation in the patient in PIK3CD (c.1340-1 G>A). All other family members were tested and defined as carriers of the same mutation and are clinically healthy. The literature states that there is an AD but also an AR form of the disease (Immunodeficiency 14 A and B, respectively) linked to the gene. The clinical phenotype of the patient fits very well the description as LOF she suffers from severe, recurrent infections since infancy and has low overall IgG levels.
Project description:BackgroundThe genetic aetiology of neurodevelopmental defects is extremely diverse, and the lack of distinctive phenotypic features means that genetic criteria are often required for accurate diagnostic classification. We aimed to identify the causative genetic lesions in two families in which eight affected individuals displayed variable learning disability, spasticity and abnormal gait.MethodsAutosomal recessive inheritance was suggested by consanguinity in one family and by sibling recurrences with normal parents in the second. Autozygosity mapping and exome sequencing, respectively, were used to identify the causative gene.ResultsIn both families, biallelic loss-of-function mutations in HACE1 were identified. HACE1 is an E3 ubiquitin ligase that regulates the activity of cellular GTPases, including Rac1 and members of the Rab family. In the consanguineous family, a homozygous mutation p.R219* predicted a truncated protein entirely lacking its catalytic domain. In the other family, compound heterozygosity for nonsense mutation p.R748* and a 20-nt insertion interrupting the catalytic homologous to the E6-AP carboxyl terminus (HECT) domain was present; western blot analysis of patient cells revealed an absence of detectable HACE1 protein.ConclusionHACE1 mutations underlie a new autosomal recessive neurodevelopmental disorder. Previous studies have implicated HACE1 as a tumour suppressor gene; however, since cancer predisposition was not observed either in homozygous or heterozygous mutation carriers, this concept may require re-evaluation.
Project description:BackgroundAutosomal recessive (AR) complete IRF8 deficiency is a rare severe inborn error of immunity underlying an absence of blood myeloid mononuclear cells, intracerebral calcifications, and multiple infections. Only three unrelated patients have been reported.Materials and methodsWe studied an Argentinian child with multiple infectious diseases and severe pulmonary alveolar proteinosis (PAP). We performed whole-exome sequencing (WES) and characterized his condition by genetic, immunological, and clinical means.ResultsThe patient was born and lived in Argentina. He had a history of viral pulmonary diseases, disseminated disease due to bacillus Calmette-Guérin (BCG), PAP, and cerebral calcifications. He died at the age of 10 months from refractory PAP. WES identified two compound heterozygous variants in IRF8: c.55del and p.R111*. In an overexpression system, the p.R111* cDNA was loss-of-expression, whereas the c.55del cDNA yielded a protein with a slightly lower molecular weight than the wild-type protein. The mutagenesis of methionine residues downstream from c.55del revealed a re-initiation of translation. However, both variants were loss-of-function in a luciferase assay, suggesting that the patient had AR complete IRF8 deficiency. The patient had no blood monocytes or dendritic cells, associated with neutrophilia, and normal counts of NK and other lymphoid cell subsets.ConclusionWe describe the fourth patient with AR complete IRF8 deficiency. This diagnosis should be considered in children with PAP, which is probably due to the defective development or function of alveolar macrophages.
Project description:Hemophagocytic lymphohistiocytosis (HLH) disease is a severe immune dysregulation caused by mutations in genes required for lymphocyte cytotoxicity function. However, HLH-like syndrome may develop secondary to infections, malignancy, and autoimmunity. Primary immunodeficiencies (PIDs) could predispose to HLH syndrome after uncontrolled infections. Mendelian susceptibility to mycobacterial disease (MSMD) is a PID characterized by a predisposition to clinical disease caused by weakly virulent mycobacteria, such as bacillus Calmette-Guérin (BCG). Inborn errors of interferon-γ immunity caused by mutations in 16 genes, underly MSMD development. Here, we report a case of fatal interferon-γ receptor 1 deficiency with disseminated BCG infection, which was initially diagnosed with HLH disease. We also include a review of cases reported in the literature.
Project description:BackgroundIntellectual disability (ID) is both a clinically diverse and genetically heterogeneous group of disorder, with an onset of cognitive impairment before the age of 18 years. ID is characterized by significant limitations in intellectual functioning and adaptive behaviour. The identification of genetic variants causing ID and neurodevelopmental disorders using whole-exome sequencing (WES) has proven to be successful. So far more than 1222 primary and 1127 candidate genes are associated with ID.MethodsTo determine pathogenic variants causative of ID in three unrelated consanguineous Pakistani families, we used a combination of WES, homozygosity-by-descent mapping, de-deoxy sequencing and bioinformatics analysis.ResultsRare pathogenic single nucleotide variants identified by WES which passed our filtering strategy were confirmed by traditional Sanger sequencing and segregation analysis. Novel and deleterious variants in VPS53, GLB1, and MLC1, genes previously associated with variable neurodevelopmental anomalies, were found to segregate with the disease in the three families.ConclusionsThis study expands our knowledge on the molecular basis of ID as well as the clinical heterogeneity associated to different rare genetic causes of neurodevelopmental disorders. This genetic study could also provide additional knowledge to help genetic assessment as well as clinical and social management of ID in Pakistani families.
Project description:We report an individual who presented with severe neurodevelopmental delay and an intractable infantile-onset seizure disorder. Exome sequencing identified a homozygous single nucleotide change that abolishes a splice donor site in the ARV1 gene (c.294 + 1G > A homozygous). This variant completely prevented splicing in minigene assays, and resulted in exon skipping and an in-frame deletion of 40 amino acids in primary human fibroblasts (NP_073623.1: p.(Lys59_Asn98del). The p.(Lys59_Asn98del) and previously reported p.(Gly189Arg) ARV1 variants were evaluated for protein expression and function. The p.(Gly189Arg) variant partially rescued the temperature-dependent growth defect in arv1Δ yeast, while p.(Lys59-Asn98del) completely failed to rescue at restrictive temperature. In contrast to wild type human ARV1, neither variant expressed detectable levels of protein in mammalian cells. Mice with a neuronal deletion of Arv1 recapitulated the human phenotype, exhibiting seizures and a severe survival defect in adulthood. Our data support ARV1 deficiency as a cause of autosomal recessive epileptic encephalopathy.