M. Hachicha

Contribution of PTPN22, CD28, CTLA-4 and ZAP-70 variants to the risk of type 1 diabetes in Tunisians.

Type 1 diabetes (T1D) is caused by an immune-mediated destruction of the insulin-producing β-cells. Several studies support the involvement of T cell activation molecules. In order to underline the role of the genes involved in this pathway, we investigated, using the Sequenom MassARRAY platform, polymorphisms of sixteen single-nucleotide polymorphisms (SNPs) belonging to PTPN22, CD28, CTLA-4, and ZAP-70 genes in 76 T1D patients and 162 unrelated healthy controls from Southern Tunisia. We confirmed the association with PTPN22 (rs2476601, Corrected P (Pcorr)=0.002, OR=6.20) and CD28 gene (rs1879877, Pcorr=0.003; OR=4.27 and rs3181096, Pcorr=0.02; OR=1.73). We also identified an association with rs17695937 of ZAP-70 gene (Pcorr=0.02, OR=1.87). Our results suggest a significant effect on T1D susceptibility for A-C-A-G-C and T-C-C-T-A-C haplotypes, of ZAP-70 and CD28 genes, respectively. In addition, (A-G-C) combination of ZAP-70/CD28 gene was significantly increased in T1D patients as compared to controls, suggesting the possible interaction between these genes. These results confirm the involvement of PTPN22 and CD28 genes in the genetic susceptibility to T1D. Interestingly, ZAP-70 seems to contribute to the susceptibility to the disease in our population. However, this finding has to be confirmed in further studies.

Clinical and Genetic Characterization of 26 Tunisian Patients with Allgrove Syndrome

BACKGROUND AND AIMS Allgrove syndrome is characterized by achalasia, alacrima, and adrenal insufficiency as well as being associated with progressive neurological signs. This is an autosomal recessive disorder due to mutations in the AAAS gene located on chromosome 12q13. The AAAS gene encodes a protein of 546 amino acids, ALADIN. Mutations in this genwere reported in families from North Africa and Europe. Our objective is to conduct a clinical, molecular and genetic study of 26 Tunisian patients with Allgrove syndrome. METHODS We report 26 Tunisian patients with between two and four clinical features associated with Allgrove syndrome. Blood samples were collected and isolated DNA derived from subjects was amplified. The entire sequence of the AAAS gene was analyzed by PCR and sequencing. PCR-RFLP method was performed to identify the frequent mutations found. RESULTS Sequencing of the AAAS gene revealed a major homozygous mutation (c.1331+1G>A) in 25 patients and R286X mutation in one patient. The presence of a major mutation in several unrelated affected individuals suggests the presence of a founder effect in Tunisia and allows for a fast and targeted molecular diagnosis. CONCLUSIONS We created an easy and rapid molecular enzymatic protocol based on PCR-RFLP using MvaI restriction enzyme that directly targets this major mutation and can be used for prenatal diagnosis and genetic counseling for Tunisian families at risk. To the best of our knowledge, this is the first major series report of Allgrove syndrome in Tunisia.

Association of TCR/CD3, PTPN22, CD28 and ZAP70 gene polymorphisms with type 1 diabetes risk in Tunisian population: family based association study.

Type 1 diabetes (T1D) is caused by an immune-mediated destruction of the insulin-producing β-cells. Several studies support the involvement of T cell activation molecules in the pathogenesis of T1D. In order to underline the role of the genes involved in this activation pathway, we investigated, using the Sequenom MassARRAY platform, 45 single-nucleotide polymorphisms (SNPs) belonging to TCR/CD3, CD28, ZAP70, and PTPN22 genes in 59 T1D Tunisian families. In the current study, we identified an association with rs706 (Z score=2.782; p=0.005) of TCRβ gene. We also demonstrated that rs10918706 in the intron of the CD3z gene was associated with increased risk of T1D (Z score 2.137; p=0.032). In the same region, rs2949655 (Z score=2.101; p=0.035) and rs1214611 (Z score=4.036; p=0.00005) showed a genotype association with the risk of T1D. When haplotypes were constructed, GAA haplotype displayed significant association with T1D (Z score=2.135; p=0.032), while GGA haplotype (Z score=-1.988; p=0.046) was negatively associated with the disease. We also identified an association with rs3181096 (Z score=2.177; p=0.029), rs17695937 (Z score =2.111; p=0.034) and rs2488457 (Z score=2.219; p=0.026), respectively of CD28, ZAP70 and PTPN22 genes. In addition, our results suggest a significant effect on T1D susceptibility for AC (Z score=2.30; p=0.02) and CTGGC (Z score=2.309, p=0.02) haplotypes of ZAP70 and PTPN22 genes, respectively. While, the GTCT (Z score=-2.114, p=0.034) and CTAGG (Z score=-2.121, p=0.033) haplotypes of CD28 and PTPN22 genes, may confer protection against T1D. These findings confirm the role of PTPN22 and CD28 involved in the T cell activation pathway in the development of T1D in Tunisian families. Interestingly, ZAP70 and TCRβ/CD3z seem to contribute to the susceptibility to the disease in our population. However, this finding has to be confirmed in further studies.

CREM variant rs17583959 conferred susceptibility to T1D risk in the Tunisian families.

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease caused by the destruction of insulin-producing pancreatic β-cells by autoreactive T cells. Studies in animal models, such as the non-obese diabetic (NOD) mouse reveal that this disease is under the control of several genes that encode molecules implicated in regulation of transcription factors and in T cell activation. In order to underline the role of the genes involved in this regulation pathways, we investigated, using the Sequenom MassARRAY platform, 13 single-nucleotide polymorphisms (SNPs) belonging to CREM, IRF5, STAT4, and STAT5a/b genes in 59 T1D Tunisian families. In the current study, we identified an association with rs17583959 (allele G; Z score=2.27; p=0.02; Genotype GG: score=1.96; p=0.04) of CREM gene. In LD analysis a strong LD between the 3 CREM variants (Block 1) was detected; rs2384352 was in complete LD with rs1148247. When haplotypes were constructed between CREM polymorphisms (rs1148247, rs17583959, rs2384352), AGA haplotype (H2) was significantly over-transmitted from parents to affected offspring (Z score=2.988; P=0.002) and may confer a risk for T1D disease. Whereas, AAG haplotype (H5) (Z score=-2.000; p=0.045) was less transmitted than expected to affected children suggesting its protective effect against T1D pathology. No significant association in IRF5, STAT4, and STAT5a/b genes were observed. In conclusion, this study shows an eventually involvement of CREM gene in the development of T1D pathology in Tunisian families. These facts are consistent with a major role for transcription factor genes involved in the immune pathways in the control of autoimmunity. Further researches of association and functional analysis across populations are needed to confirm these findings.

Érythroblastopénie aiguë secondaire à une infection par le Parvovirus B19 révélant une sphérocytose héréditaire chez 2 enfants de la même famille.

Acute Parvovirus B19 infection is responsible for blocking the erythroblastic line, usually with no consequences on hematopoiesis except in patients with chronic hemolytic anemia in whom it can evolve to potentially serious acute anemia. We report 2 observations of acute erythroblastopenia revealing hereditary spherocytosis in 2 children (1 boy and 1 girl) of non-consanguineous parents.

Le syndrome des antiphospholipides à propos d’une nouvelle observation pédiatrique

UNLABELLED Many conditions can lead to cerebral strokes in children. The antiphospholipid syndrome widely described in adults in association with systemic lupus erythematosus, is rare in childhood. CASE REPORT Two months after recovering from varicella and a few days after an episode of bronchitis, a 17-month-old girl developed left facial paralysis associated with right hemiplegia. Brain MRI and angio-scan showed thrombosis in the internal left carotid associated with ischemia in the superficial posterior territory of the left Sylvian artery. Echocardiography and hemoglobin electrophoresis were normal. Tests were negative for protein S, C and antithrombin III deficiencies and no resistance to activated protein C. IgM anticardiolipin antibodies were detected at high level (greater than 25IU/l) initially and six weeks later. In the absence of an evident etiology, mainly systemic lupus erythematosus (negative antinuclear antibodies), the diagnosis of primary antiphospholipid syndrome was retained. The girl was treated by heparin then by salicylate at antiaggregate doses associated with re-habilitation. Twelve months later, the patient had not developed any other thrombosis, in spite of a high level of anticardiolipin antibodies. CONCLUSION In children with cerebral strokes, antiphospholipid syndrome must be discussed when the usual etiologies have been ruled out.

Déficit congénital en facteur VII de la coagulation, révélé par une hémorragie cérébrale

Constitutional factor VII deficiency is a hereditary disease with recessive autosomic transmission. Its incidence is estimated to be 1/1,000,000 in the general population. We report a case of severe factor VII deficiency in infancy revealed by an intracranial hemorrhage in a 2-month-old infant. We describe the clinical, biological and therapeutic characteristics of this disease.

Fulminant mulch pneumonitis in a previously healthy child

Chronic granulomatous disease (CGD) is associated with multiple and recurrent infections. In patients with CGD, invasive pulmonary infection with aspergillus species remains the greatest cause of mortality. Acute fulminant presentations of fungal pneumonia are catastrophic. It is a medical emergency, and currently the treatment is based on association of corticosteroids and antifungal therapy. We describe the case of an 11-year-old boy, with late initial presentation of CGD, which was revealed by fulminant aspergillus pneumonia. He was successfully treated with an association of high doses of steroids and voriconazole.

Familial haemophagocytosis lymphohisticytosis type 3: A case report

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare autosomal recessive disorder of immune regulation. Here, we report on a fatal case of type 3 FHL (FHL3) in a 45-day-old boy. Clinically, the infant presented with fever and hepatosplenomegaly. Biology showed pancytopenia, elevated ferritin, and decreased fibrinogen. Images of hemophagocytosis were found at the bone morrow examination. The diagnosis of FHL type 3 was made by the identification of homozygous mutation in the Munc13-4 gene (UNC13D) located in exon 20: 1822 del 12bp (V608fs). This mutation was previously observed in a Tunisian and in Moroccan families.

Macrophagic activation syndrome related to an infection by Rickettsia conorii in a child.

Since the Arab Spring, a resurgence of zoonotic diseases such as rickettsiosis, endemic in the Mediterranean basin, has been observed. It preferentially infects microvascular endothelial cells of mammalian hosts inducing vasculitis with endothelial injury. Rickettsioses are considered benign infectious diseases. Severe systemic manifestations have been reported and are often explained by a delay in diagnosis. We present a case of hemophagocytic syndrome occurring in a 4-year-old Libyan girl as a complication of Mediterranean spotted fever. Rickettsial infection was confirmed by serology and the patient was treated with clarithromycin, with a favorable outcome.