Tunisian Toxoplasma gondii strains genotyping by the use of AK69 marker

<p>Abstract</p> <p>Background</p> <p>Clinical manifestation due to infection by <it>Toxoplasma gondii </it>is closely linked to the infecting strain of the parasite. Several genetic markers are available to determinate its genotype but few of them are able to discriminate between the three predominant lineages, namely types I, II and III. The number of markers decreases when atypical, recombinant/mixed genotypes need to be identified.</p> <p>Findings</p> <p>In our study, the contribution of sequence polymorphisms in the AK69 gene as typing markers for <it>T. gondii </it>was investigated for the first time in an epidemiological study. The coding region of the marker was amplified, sequenced and aligned for different <it>Toxoplasma </it>strains. The identified nucleotide polymorphism at 12 positions was able to highly discriminate between the different congenital toxoplasmosis Tunisian strains. Moreover the high detection sensitivity level of the marker enabled unambiguous identification of mixed/recombinant genotypes directly.</p> <p>Conclusion</p> <p>It can be, thus, very useful for direct typing in areas where such genotypes are frequently encountered, mainly in the African continent.</p

Omenn Syndrome : Two Case Reports

Omenn syndrome is a variant of combined severe immunodeficiencydue to mutations in RAG genes. It is characterized by polymorph symptoms andlethal outcome. We report on two cases of Omenn syndrome. Infants were aged 50and 46 days. The clinical and biological signs were typical and complete in the firstcase. In the second case, only the cutaneous signs were present. Diagnosis was confirmedby genetic study. The Rag1 T631 mutation was found in these two patients.Hematopoietic stem cell transplantation could not be done and the evolution wasfatal in both cases because of severe infectious episodes. Prenatal diagnosis wasperformed in the two families and each family has currently a healthy child. In conclusion,early diagnosis of Omenn syndrome may avoid infectious complicationsresponsible for delay in therapeutic management. Genetic study confirms the diagnosis.The treatment usually consists of hematopoietic stem cell transplantationin association with immunosuppressive drugs. Prenatal diagnosis is very importantto allow parents to have healthy children.</p

Novel sequence variations in LAMA2 andSGCG genes modulating cis-acting regulatory elements and RNA secondary structure

In this study, we detected new sequence variations in LAMA2 and SGCG genes in 5 ethnic populations, and analysed their effect on enhancer composition and mRNA structure. PCR amplification and DNA sequencing were performed and followed by bioinformatics analyses using ESEfinder as well as MFOLD software. We found 3 novel sequence variations in the LAMA2 (c.3174+22_23insAT and c.6085 +12delA) and SGCG (c. * 102A/C) genes. These variations were present in 210 tested healthy controls from Tunisian, Moroccan, Algerian, Lebanese and French populations suggesting that they represent novel polymorphisms within LAMA2 and SGCG genes sequences. ESEfinder showed that the c. * 102A/C substitution created a new exon splicing enhancer in the 3'UTR of SGCG genes, whereas the c.6085 +12delA deletion was situated in the base pairing region between LAMA2 mRNA and the U1snRNA spliceosomal components. The RNA structure analyses showed that both variations modulated RNA secondary structure. Our results are suggestive of correlations between mRNA folding and the recruitment of spliceosomal components mediating splicing, including SR proteins. The contribution of common sequence variations to mRNA structural and functional diversity will contribute to a better study of gene expression

An Unusual Case of Peters Plus Syndrome with Sexual Ambiguity and Absence of Mutations in the B3GALTL Gene

Background: Peters Plus syndrome (MIM 261540) is a rare autosomal recessive condition characterized by ocular defects (typically Peters anomaly) and other systemic major/minor abnormalities. Mutations in the B3GALTL gene encoding the β-1,3-glucosyltransferase have been found in virtually all patients with typical Peters Plus syndrome. Case Presentation: We report here a female patient with severe manifestations of Peters Plus syndrome including facial dysmorphism and bilateral corneal opacity associated with left renal pyelo-calicial dilatation and sexual ambiguity. Total sequencing of the B3GALTL gene revealed no mutation in the patient. Conclusion: To our knowledge, sexual ambiguity has not previously been reported in Peters Plus syndrome so far, and renal malformation is also apparently rare in the syndrome

LAMA2 mRNA processing alterations generate a complete deficiency of laminin-alpha2 protein and a severe congenital muscular dystrophy.

An increasing number of genomic variations are no more regarded as harmless changes in protein coding sequences or as genetic polymorphisms. Studying the impact of these variations on mRNA metabolism became a central issue to better understand the biological significance of disease. We describe here a severe congenital muscular dystrophy (CMD) with lumbar scoliosis and respiratory complications in a patient, who died at the age of 10. Despite a poor linkage to any form of CMD, total deficiency of laminin-alpha2 rather suggested the occurrence of an MDC1A form. Extensive analysis of LAMA2 gene revealed two novel mutations: a (8007delT) frameshift deletion in exon 57, and a de novo 7nt deletion in intron 17. Using an ex vivo approach, we provided strong evidence that the intron mutation is responsible for complete exon 17 skipping. The mutations are in trans and they each generate a nonsense mRNA potentially elicited to degradation by NMD. We further discuss the impact of mRNA alterations on the subtle phenotypic discrepancies

Genetic analysis of Turner syndrome in Tunisian patients: from diagnosis to management

Background/aim Turner syndrome (TS) is a rare sex chromosome abnormality in women, occurring in approximately one in 2500 live births, associated with a wide range of clinical stigmata of which short stature, ovarian dysgenesis, and dysmorphic features are the most frequent. Morbidity and mortality are clearly increased compared with the general population, and the average age at diagnosis is quite delayed. Even if the majority of females with TS have a non-mosaic 45,X karyotype, several karyotype variations exist, including short or long arm deletion, ring X isochromosome of the long arm, and 45,X 46,XX mosaicism. This explains the large phenotypic and genetic heterogeneities of TS, which make the diagnosis and especially the management increasingly difficult. We present in this work a genetic study of TS in the Tunisian population to establish a genotype–phenotype correlation, which would be of great help for the diagnosis and the care of patients. Patients and methods A total of 26 unrelated Tunisian girls were included in this study. All patients underwent a complete clinical and biochemical examination as well as karyotyping. The screening for the SRY gene was carried out by fluorescence in-situ hybridization or by PCR. Results Cytogenetic results showed a prevalence of the 45,X karyotype in 46% of patients and various proportions of the other karyotypes. However, genotype–phenotype correlation revealed several discrepancies regarding the major signs and the age at diagnosis. The comparison of the approaches used for the screening of the SRY gene showed that karyotyping is unable to detect low 45,X/46,XY mosaicism and that it is the PCR that would be able to do, eliciting its role to make a reliable diagnosis. Conclusion The karyotype alone is not sufficient to make a TS diagnosis in cases of weak mosaicism, and the great heterogeneity that reigns the syndrome elicits an epigenetic and transcriptomic exploration of several genes that recently seem to be involved in the disease

Severe MDC1A congenital muscular dystrophy due to a splicing mutation in the LAMA2 gene resulting in exon skipping and significant decrease of mRNA level.

Congenital muscular dystrophies (CMDs) are a clinically and genetically heterogeneous group of neuromuscular disorders, with autosomal recessive inheritance. We report a patient with severe congenital muscular dystrophy and total deficiency in the laminin alpha2 chain. Genetic analyses showed a linkage to the MDC1A locus for the patient's family, and DNA sequencing revealed in the propositus of a new homozygous mutation in the donor splice site of intron 58 of the LAMA2 gene. RT-PCR experiments performed on total RNA from a patient's muscle biopsy showed a complete skipping of exon 58 in LAMA2 cDNA and a significant decrease in the LAMA2 mRNA level. This exon skipping altered the open reading frame of the mutant transcript and generated a premature termination codon (PTC) within exon 59, which potentially elicits the nonsense mRNA to degradation by NMD (nonsense-mediated mRNA decay). However, the residual exon 58-lacking mRNA could potentially be translated, and the resulting truncated alpha2 chain would lack its LG4 and LG5 domains that are involved in binding with alpha-dystroglycan. These results demonstrate the utility of mRNA analysis to understand the mutation primary impact and the disease phenotype in the patients