Sellama Nadifi

Hypomorphic homozygous mutations in phosphoglucomutase 3 (PGM3) impair immunity and increase serum IgE levels

BACKGROUND Recurrent bacterial and fungal infections, eczema, and increased serum IgE levels characterize patients with the hyper-IgE syndrome (HIES). Known genetic causes for HIES are mutations in signal transducer and activator of transcription 3 (STAT3) and dedicator of cytokinesis 8 (DOCK8), which are involved in signal transduction pathways. However, glycosylation defects have not been described in patients with HIES. One crucial enzyme in the glycosylation pathway is phosphoglucomutase 3 (PGM3), which catalyzes a key step in the synthesis of uridine diphosphate N-acetylglucosamine, which is required for the biosynthesis of N-glycans. OBJECTIVE We sought to elucidate the genetic cause in patients with HIES who do not carry mutations in STAT3 or DOCK8. METHODS After establishing a linkage interval by means of SNPchip genotyping and homozygosity mapping in 2 families with HIES from Tunisia, mutational analysis was performed with selector-based, high-throughput sequencing. Protein expression was analyzed by means of Western blotting, and glycosylation was profiled by using mass spectrometry. RESULTS Mutational analysis of candidate genes in an 11.9-Mb linkage region on chromosome 6 shared by 2 multiplex families identified 2 homozygous mutations in PGM3 that segregated with disease status and followed recessive inheritance. The mutations predict amino acid changes in PGM3 (p.Glu340del and p.Leu83Ser). A third homozygous mutation (p.Asp502Tyr) and the p.Leu83Ser variant were identified in 2 other affected families, respectively. These hypomorphic mutations have an effect on the biosynthetic reactions involving uridine diphosphate N-acetylglucosamine. Glycomic analysis revealed an aberrant glycosylation pattern in leukocytes demonstrated by a reduced level of tri-antennary and tetra-antennary N-glycans. T-cell proliferation and differentiation were impaired in patients. Most patients had developmental delay, and many had psychomotor retardation. CONCLUSION Impairment of PGM3 function leads to a novel primary (inborn) error of development and immunity because biallelic hypomorphic mutations are associated with impaired glycosylation and a hyper-IgE-like phenotype.

The Aurora Kinase C c.144delC mutation causes meiosis I arrest in men and is frequent in the North African population

Infertility concerns a minimum of 70 million couples worldwide. An important proportion of cases is believed to have a genetic component, yet few causal genes have been identified so far. In a previous study, we demonstrated that a homozygous mutation (c.144delC) in the Aurora Kinase C (AURKC) gene led to the production of large-headed polyploid multi-flagellar spermatozoa, a primary infertility phenotype mainly observed in North Africans. We now want to estimate the prevalence of the defect, to improve our understanding of AURKC physiopathology in spermatogenesis and assess its implication in oogenesis. A carrier frequency of 1/50 was established from individuals from the Maghrebian general population, comparable to that of Y-microdeletions, thus far the only known recurrent genetic event altering spermatogenesis. A total of 62 patients were genotyped, all who had a typical phenotype with close to 100% large-headed spermatozoa were homozygously mutated (n = 32), whereas no AURKC mutations were detected in the others. Two homozygous females were identified; both were fertile indicating that AURKC is not indispensible in oogenesis. Previous FISH results had showed a great chromosomal heterogeneity in these patients spermatozoa. We demonstrate here by flow cytometry that all spermatozoa have in fact a homogeneous 4C DNA content and are thus all blocked before the first meiotic division. Our data thus indicate that a functional AURKC protein is necessary for male meiotic cytokinesis while its absence does not impair oogenesis.

BRCA1 and BRCA2 germline mutations in Moroccan breast/ovarian cancer families: Novel mutations and unclassified variants

OBJECTIVE Breast cancer is the most common female cancer in Morocco. About 5 to 10% are due to hereditary predisposition and mutations in BRCA1 and BRCA2 genes are responsible for an important proportion of high-risk breast/ovarian cancer families. The relevance of BRCA1/2 mutations in the Moroccan population was not studied. The main objective of this study is to investigate the spectrum of BRCA1 and BRCA2 germline mutations in early onset and familial breast/ovarian cancer among Moroccan women. METHODS We screened the entire coding sequences and intron/exon boundaries of BRCA1 and BRCA2 genes in 40 patients by direct sequencing. RESULTS Nine pathogenic mutations were detected in ten unrelated families, five deleterious mutations in BRCA1 gene and four mutations in BRCA2 gene. Four novel mutations were found: one in BRCA1 (c.2805delA/2924delA) and three in BRCA2 (c.3381delT/3609delT; c.7110delA/7338delA and c.7235insG/7463insG). We also identified 51 distinct polymorphisms and unclassified variants (three described for the first time). CONCLUSIONS Our data suggest that BRCA1 and BRCA2 mutations are responsible for a significant proportion of familial breast cancer in Moroccan patients. Therefore full BRCA1/2 screening should be offered to patients with a family history of breast/ovarian cancer.

Autosomal recessive and sporadic deafness in Morocco: High frequency of the 35delG GJB2 mutation and absence of the 342-kb GJB6 variant

Deafness is a heterogeneous disorder showing different pattern of inheritance and involving a multitude of different genes. Mutations in the gene, GJB2 Gap junction type 1), encoding the gap junction protein connexin-26 on chromosome 13q11 may be responsible for up 50% of autosomal recessive nonsyndromic hearing loss cases (ARNSHL), and for 15-30% of sporadic cases. However, a large proportion (10-42%) of patients with GJB2 has only one GJB2 mutant allele. Recent reports have suggested that a 342-kb deletion truncating the GJB6 gene (encoding connexin-30), was associated with ARNSHL through either homozygous deletion of Cx30, or digenic inheritance of a Cx30 deletion and a Cx26 mutation in trans. Because mutations in Connexin-26 (Cx26) play an important role in ARNSHL and that distribution pattern of GJB2 variants differs considerably among ethnic groups, our objective was to find out the significance of Cx26 mutations in Moroccan families who had hereditary and sporadic deafness. One hundred and sixteen families with congenital deafness (including 38 multiplex families, and 78 families with sporadic cases) were included. Results show that the prevalence of the 35delG mutation is 31.58% in the family cases and 20.51% in the sporadic cases. Further screening for other GJB2 variants demonstrated the absence of other mutations; none of these families had mutations in exon 1 of GJB2 or the 342-kb deletion of GJB6. Thus, screening of the 35delG in the GJB2 gene should facilitate routinely used diagnostic for genetic counselling in Morocco.

Large-scale meta-analysis of genetic studies in ischemic stroke: Five genes involving 152,797 individuals.

BACKGROUND: Ischemic stroke descent has a genetic basis. Stroke represents a complex trait, which is assumed to be polygenic. On this topic, the role of a wide number of candidate genes has been investigated in stroke through association studies. MATERIALS AND METHODS: We performed a literature-based systematic review of genetic association studies in stroke abound several populations. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for each gene-disease association. Following a review of 300 manuscripts, five candidate gene variants were analyzed among 152,797 individuals (45,433 cases and 107,364 controls). RESULTS: For these five candidate genes studied, the prothrombin OR is 1,57 (1,23-2,89), the factor V Leiden OR is 1,43 (0,67-6,24), the mean OR of angiotensin I converting enzyme (ACE) insertion/deletion (I/D) polymorphism is 1,11 (1,02-1,25), the summary OR for the C677T variant of 5,10-methylenetetrahydrofolate reductase (MTHFR) is 1,23 (0,61-1,47) and the pooled OR for the apolipoprotein E (APOE) gene is 0,95 (0,77-1,14) . CONCLUSION: These data suggest the genetic associations of some genes with ischemic stroke and it is necessary to compete with other genes. Our findings could represent an epidemiological base and a useful tool to address further molecular investigations and to realize more detailed meta-analyses.

Prevalence of angiotensin-converting enzyme, methylenetetrahydrofolate reductase, Factor V Leiden, prothrombin and apolipoprotein E gene polymorphisms in Morocco

Background: Evidence of the influence of genetic risk factors on cardiovascular diseases is more or less established. These genetic factors are involved in several pathways affecting blood pressure regulation, blood coagulation, homocysteine and lipid metabolisms. Aim: We evaluated frequencies of five genetic polymorphisms to assess their informativeness as markers for prospective clinical studies. Subjects and methods: 182 healthy Moroccan subjects were genotyped for ACE I/D by amplification alone and by amplification followed by enzymatic digestion for other polymorphisms. Results: Allele frequencies of ACE ID, MTHFR C677T were 76.6%, 26.9% for D and T alleles, respectively. APOE polymorphism showed 11.3%, 78.6% and 10.2% for the alleles E2, E3 and E4, respectively. The frequency for FII G20210A polymorphism was around 2.7% for A allele. Our data showed an absence of FVL mutation. Using allele frequencies, genetic distances between Moroccan and other populations revealed an independent variability of these polymorphisms. Conclusion: These values appear to be influenced by findings in European and African peoples, and may be considered in assessing the clinical significance of a predisposition to cardiovascular disease.

Toll-like receptor 4 Asp299Gly and Thr399Ile polymorphisms: New data and a meta-analysis.

BackgroundThe pathogenesis of inflammatory bowel disease (IBD) involves interactions between the host genetic susceptibility, intestinal microflora and mucosal immune responses through the pattern recognition receptor. Polymorphisms in toll-like receptor 4 (TLR4) induce an aberrant immune response to indigenous intestinal flora, which might favor IBD development. In this study, we aimed to determine whether TLR4 gene was associated with Crohn’s disease (CD) and ulcerative colitis (UC) among Moroccan patients, and evaluated its correlation with clinical manifestation of the disease.MethodsThe study population comprised 117 patients with IBD and 112 healthy unrelated blood donors. TLR4 polymorphisms: Asp299Gly and Thr399Ile were genotyped by polymerase chain reaction-restriction fragment length polymorphism. PCR products were cleaved with Nco I for the Asp299Gly polymorphism and Hinf I for the Thr399Ile polymorphism. Meta-analysis was performed to test the association of 299Gly and 399Ileu carriage with CD, UC and the overall IBD risk.ResultsOur study revealed that the frequency of Asp299Gly and Thr399Ile did not differ significantly between patients and controls in the Moroccan population. However, meta-analysis demonstrated significantly higher frequencies of both Asp299Gly and Thr399Ile SNPs in IBD and CD and for 399Ileu carriage in UC patients.ConclusionThe meta-analysis provides evidence that TLR4 polymorphisms confer a significant increased risk for the overall IBD development.

Biomarkers for Alzheimer disease: Classical and novel candidates’ review

The biomarkers may be useful for predictive diagnosis of Alzheimers disease (AD). The current challenge is to diagnose it in its preclinical phase. The combination of cerebrospinal fluid (CSF) biomarkers and imaging has been investigated extensively for a number of years. It can provide an increased diagnostic accuracy. This review discusses the contribution of classical biomarkers to predict AD and highlights novel candidates identified as potential markers for AD. We referred to the electronic databases PubMed/Medline and Web of Science to search for articles that were published until February 2016. Sixty-two records were included in qualitative synthesis. In the first section, the results show the contribution of biomarkers to predict and track AD considered as classical biomarkers. In the second section, the results highlight the involvement of novel candidates that should be considered for future evaluation in the characterization of the AD progression. Reported findings open prospect to define noninvasive biomarkers to predict AD before symptoms onset.

Ten-year follow-up of a DOCK8-deficient child with features of systemic lupus erythematosus.

Dedicator of cytokinesis 8 (DOCK8) deficiency is an innate error of adaptive immunity characterized by recurrent infections with viruses, bacteria, and fungi, typically high serum levels of immunoglobulin E, eosinophilia, and a progressive deterioration of T- and B-cell–mediated immunity. DOCK8 mutations are the second most common cause of hyper–immunoglobulin E syndromes (HIES). We report a case of DOCK8 deficiency associated with systemic lupus erythematosus (SLE). Association of SLE with HIES is very rare; to our knowledge, this is the sixth such case reported in the literature. A 10-year-old girl of consanguineous parents was followed in our clinic because of HIES since early childhood. She developed SLE with purpuric and necrotic skin lesions, diffuse arthritis, and glomerulonephritis. These autoimmune features were corroborated by the presence of antinuclear, anti-DNA, and antiphospholipid antibodies. The combination of HIES and autoimmunity makes treatment difficult, because the use of immunosuppressive drugs needed for SLE may worsen existing symptoms caused by the immunodeficiency. Our observation is the first case of association of SLE with HIES in the literature where the primary immune disease is genetically documented and labeled as DOCK8 deficiency.

IL23R and ATG16L1 variants in Moroccan patients with inflammatory bowel disease

BackgroundInflammatory bowel diseases (IBD) are chronic diseases of the gastrointestinal tract. Although their pathogenesis is unclear, the combination of genetic predisposition and environmental components are believed to be the main cause of these diseases. Recently, many variants in interleukin 23 receptor (IL23R) and autophagy-related 16-like 1 (ATG16L1) genes have been associated with the disease. Our objective was to assess the frequency of ATG16L1 (T300A) and IL23R (L310P) variants in Moroccan IBD (Crohn’s disease and Ulcerative Colitis) patients and to evaluate a possible effect of these variants on disease’s phenotype and clinical course.Methods96 Moroccan IBD patients and 114 unrelated volunteers were genotyped for ATG16L1 (T300A) and IL23R (L310P) variants by PCR-restriction fragment length polymorphism.ResultsThis is the first report on the prevalence of ATG16L1 (T300A) and IL23R (L310P) variants in a Moroccan group. We found that IL23R (L310P) variant conferred a protective effect for crohn’s disease (CD) but not ulcerative colitis (UC) patients. The presence of ATG16L1 (T300A) mutated alleles was associated with CD type but not with disease onset. In addition, the carriage of T300A variant alleles conferred a protective effect in UC.ConclusionOur results showed that the prevalence of ATG16L1 and IL23R variants was not significantly different between patients and controls. However a possible role of ATG16L1 (T300A) on CD phenotype was suggested.