Cupressus sempervirens Essential Oil: Exploring the Antibacterial Multitarget Mechanisms, Chemcomputational Toxicity Prediction, and Safety Assessment in Zebrafish Embryos.

Nowadays, increasing interest has recently been given to the exploration of new food preservatives to avoid foodborne outbreaks or food spoilage. Likewise, new compounds that substitute the commonly used synthetic food preservatives are required to restrain the rising problem of microbial resistance. Accordingly, the present study was conducted to examine the chemical composition and the mechanism(s) of action of the Cupressus sempervirens essential oil (CSEO) against Salmonella enterica Typhimuriumand Staphyloccocus aureus. The gas chromatography analysis revealed α-pinene (38.47%) and δ-3-carene (25.14%) are the major components of the CSEO. By using computational methods, such as quantitative structure-activity relationship (QSAR), we revealed that many CSEO components had no toxic effects. Moreover, findings indicated that α-pinene, δ-3-carene and borneol, a minor compound of CSEO, could inhibit the AcrB-TolC and MepR efflux pump activity of S. enterica Typhimurium and S. aureus, respectively. In addition, our molecular docking predictions indicated the high affinity of these three compounds with active sites of bacterial DNA and RNA polymerases, pointing to plausible impairments of the pathogenic bacteria cell replication processes. As well, the safety profile was developed through the zebrafish model. The in vivo toxicological evaluation of (CSEO) exhibited a concentration-dependent manner, with a lethal concentration (LC50) equal to 6.6 µg/mL.

Congenital lamellar ichthyosis in Tunisia is caused by a founder nonsense mutation in the TGM1 gene.

Lamellar ichthyosis (LI, MIM# 242300) is a severe autosomal recessive genodermatosis present at birth in the form of collodion membrane covering the neonate. Mutations in the TGM1 gene encoding transglutaminase-1 are a major cause of LI. In this study molecular analysis of two LI Tunisian patients revealed a common nonsense c.788G>A mutation in TGM1 gene. The identification of a cluster of LI pedigrees carrying the c.788G>A mutation in a specific area raises the question of the origin of this mutation from a common ancestor. We carried out a haplotype-based analysis by way of genotyping 4 microsatellite markers and 8 SNPs flanking and within the TGM1 gene spanning a region of 6 Mb. Haplotype reconstruction from genotypes of all members of the affected pedigrees indicated that all carriers for the mutation c.788G>A harbored the same haplotype, indicating common ancestor. The finding of a founder effect in a rare disease is essential for the genetic diagnosis and the genetic counselling of affected LI pedigrees in Tunisia.

Short-term effects of various non-steroidal anti-inflammatory drugs (NSAIDs) on Danio rerio embryos.

Due to the widespread use of non-steroidal anti-inflammatory drugs (NSAIDs) without a medical prescription and their frequent prevalence in aquatic habitats, there are major health and environmental issues. NSAIDs have been found in surface water and wastewater in concentrations ranging from ng/L to µg/L all over the world. The purpose of this study was to determine the relationship between NSAIDs (diclofenac, ketoprofen, paracetamol and ibuprofen) exposure and associated adverse effects in the assessment of indirect human health risks posed by Danio rerio (zebrafish) and Environmental Risk Assessment (ERA) of these NSAIDs in aquatic environments. Therefore, the objectives of this study were to (i) reveal abnormality endpoints of early developmental stages, after exposure of zebrafish and (ii) perform an ecological risk assessment of aquatic organisms upon exposure to NSAIDs detected in surface waters based on the risk quotients (RQs) method. According to the toxicity data collected, all of the malformations appeared after diclofenac exposure at all concentrations. The most notable malformations were the lack of pigmentation and an increase in yolk sac volume, with EC50 values of 0.6 and 1.03 mg/L, respectively. The results obtained for the ERA revealed RQs higher than 1 for all the four NSAIDs chosen, posing ecotoxicological pressure in aquatic environments. Overall, our findings provide a critical contribution to the formulation of high-priority actions, sustainable strategies and strict regulations that minimize the negative effects of NSAIDs on the aquatic ecosystem.•To determine the LC50, lethal conditions such as coagulation, absence of heartbeat and blood flow, absence of tail separation and development of somites were taken into account.•The EC50 was calculated using sublethal parameters such as blood coagulation, pericardial edema, yolk sac edema or hypertrophy.•The 4 compounds present a high risk individually and in mixture with a RQ >> 1.

Impact of single-nucleotide polymorphisms at the TP53-binding and responsive promoter region of BCL2 gene in modulating the phenotypic variability of LGMD2C patients.

Apoptosis of skeletal muscle fibers is a well-known event occurring in patients suffering from muscular dystrophies. In this study, we hypothesized that functional polymorphisms in genes involved in the mitochondrial apoptotic pathway might modulate the apoptotic capacity underlying the muscle loss and contributing to intrafamilial and interfamilial variable phenotypes in LGMD2C (Limb Girdle Muscular Dystrophy type 2C) patients sharing the same c.521delT mutation in SGCG gene. Detection of apoptosis was confirmed on muscle biopsies taken from LGMD2C patients using the TUNEL method. We genotyped then ten potentially functional SNPs in TP53, BCL-2 and BAX genes involved in the mitochondrial apoptotic pathway. Potential genotype-dependent Bcl-2 and p53 protein expressed in skeletal muscle was investigated using western blot and ELISA assays. The result showed that muscle cells carrying the TP53-R72R and TP53-16 bp del/del genotypes displayed an increased p53 level which could be more effective in inducing apoptosis by activation of the pro-apoptotic gene expression. In addition, the BCL2-938 AA genotype was associated with increased Bcl-2 protein expression in muscle from LGMD2C patients compared to -938CC genotype, while there was no evidence of significant difference in the BAX haplotype. Our findings suggest that increased Bcl-2 protein expression may counteract pro-apoptotic pathways and thus reduce the muscle loss. To the best of our knowledge, this is a pioneer study evaluating the role of apoptotic BCL-2 and TP53 genes in contributing to the phenotypic manifestation of c.521delT mutation in LGMD2C patients. Larger studies are needed to validate these findings.

Congenital factor XIII deficiency caused by two mutations in eight Tunisian families: molecular confirmation of a founder effect.

Inherited factor XIII (FXIII) deficiency is a rare bleeding disorder characterized by an umbilical bleeding during the neonatal period, delayed soft tissue bruising, mucosal bleeding spontaneous intracranial hemorrhage, and soft tissue hemorrhages. Congenital FXIII deficiency is an autosomal recessive disorder, usually attributed to a defect in the FXIIIA and B subunits coding, respectively, by F13A and F13B genes. The aim of this study was to determine the molecular defects responsible for congenital factor XIII deficiency in eight Tunisian families. Molecular analysis was performed by direct DNA sequencing of polymerase chain reaction amplified fragments spanning the coding regions and splice junctions of the FXIIIA subunit gene (F13A) in probands and in families' members and compared with the reported sequence of this gene. In all patients, FXIIIA activity was undetectable and the FXIIIB was within the normal range. Direct sequencing of the F13A gene in all probands showed two mutations: the c.869insC mutation found in eight patients and the c.1226G > A transition found in only one. We also confirmed the presence of a founder effect for the first frequent mutation by using two microsatellite markers, HUMF13A01 and a generated ployAC marker (HUMF13A02). We describe here molecular abnormalities found in nine Tunisian probands diagnosed with FXIIIA deficiency. The identification of the founder mutation and polymorphisms allowed a genetic counseling in relatives of these families, and the antenatal diagnosis is now available.

Thyroid involvement in Chanarin-Dorfman syndrome in adults in the largest series of patients carrying the same founder mutation in ABHD5 gene.

BACKGROUND: Chanarin-Dorfman syndrome (CDS) is a rare syndromic disease related to an accumulation of triacylglycerol in most organs. The aim of our study was to investigate various organs in a large series of CDS patients. RESULTS: We report for the first time thyroid function impairment in CDS. Among 12 investigated patients, 7 showed thyroid function impairment. All of them were over 30 of age. The 5 remaining investigated patients with normal thyroid function were under 30. Thyroid loss of function is an unknown clinical feature of CDS that could gradually develop with age. Thyroid ultrasound showed an abnormal aspect in all investigated patients (6 with thyroid impairment and 3 with normal thyroid function). Cervical MRI done in 2 patients with thyroid impairment showed fat infiltration of thyroid parenchyma. Audiogram carried out in 8 of our patients showed sensorineural hearing impairment in all patients, although only 2 patients suffered from clinical hypoacusia. We also demonstrated that kidney could be a more commonly involved organ than previously reported in the literature. A poorly differentiated kidney parenchyma is a common feature in our series. One patient showed cerebellar atrophy and T2 hypersignal of brain's white matter in MRI. All patients carried the same founder mutation c.773(- 1)G > A in the ABDH5 gene. DISCUSSION: Aside from the congenital ichthyosiform erythroderma, the most common symptom of CDS, in addition to other organs involvement frequently reported in the literature, we described thyroid dysfunction, an unreported feature, probably related to the lipid infiltration of the thyroid parenchyma. The association found between age and hypothyroidism in CDS patients could explain the gradually development of thyroid disease with age. CONCLUSION: We reported a thyroid dysfunction and unreported ultrasonographic aspects of kidneys and cerebral MRI in CDS patients. METHODS: We performed clinical analyses in 15 patients in whom thyroid, liver, ocular, kidney, skeletal muscle and neurological involvement were explored. Genetic and molecular explorations were performed by direct sequence analysis. Software SPSS, Fisher's exact test and ANOVA were used for statistical analyses.

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.

Molecular prenatal diagnosis of muscular dystrophies in Tunisia and postnatal follow-up role.

We undertook in this study the first successful prenatal diagnoses of MDC1A and LGMD2C forms in Africa, with a subsequent postnatal clinical follow-up of the newborns. Genetic and molecular studies were performed on cultured amniotic fluid cells after exclusion of maternal cell contamination. Immunofluorescence on the patients' muscle biopsies was performed so as to study the expression of muscular laminins. Results showed that normal and affected fetuses were diagnosed according to the presence or the absence of the responsible mutation in LAMA2 or SGCG genes. Postnatal molecular and clinical outcome was concordant with all prenatal diagnoses. However, a patient with MDC1A form of congenital muscular dystrophy who was diagnosed as affected was normal at birth, and developed later clinical features different from those observed in his severely affected elder brother. This intrafamilial clinical variability in two siblings occurring with the same mutation in LAMA2 gene emphasizes the importance of the postnatal follow-up in the confirmation of prenatal diagnosis, and suggests that other genetic or epigenetic factors can monitor the course of the MDC1A form.

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.

Original tandem duplication in FXIIIA gene with splicing site modification and four amino acids insertion causes factor XIII deficiency.

: Recessive mutations of F13A gene are reported to be responsible of FXIIIA subunit deficiency (FXIIIA). In all, some intronic nucleotide changes identified in this gene were investigated by in-silico analysis and occasionally supported by experimental data or reported in some cases as a polymorphism. To determine the molecular defects responsible of congenital factor XIII deficiency in Libyan patient, molecular analysis was performed by direct DNA sequencing of the coding regions and splice junctions of the FXIIIA subunit gene (F13A). A splicing minigene assay was used to study the effect of this mutation. Bioinformatics exploration was fulfilled to conceive consequences on protein. A 12-bp duplication straddling the border of intron 9 and exon 10 leads to two 3' acceptor splice sites, resulting in silencing of the downstream wild 3' splice site. It caused an in-frame insertion of 12 nucleotides into mRNA and four amino acids into protein. Bioinformatic analysis predicts that the insertion of four amino acids affects the site 3 of calcium binding site, which disturbs the smooth function of the FXIIIA peptide causing the factor XIII deficiency. This study showed that a small duplication seems to weaken the original 3' splice site and enhance the activation of a new splice site responsible for an alternative splicing. It would be interesting to examine the underlying molecular mechanism involved in this rearrangement.

Factor XIII deficiency in south of Tunisia.

: Factor XIII deficiency is a rare autosomal recessive disorder of hemostasis characterized by a plasmatic factor XIII level less than 1% in homozygote and bleeding as of the youth. The aim of the study is to describe the clinical features and the outcome of the patients and to determine molecular characteristics. A retrospective study, was conducted on seven patients with factor XIII deficiency in the department of hematology and pediatrics, Hedi Chaker Hospital, Sfax, Tunisia during the period of 14 years (2001-2014). The activity of factor XIII in plasma of the patients was less than 1%. Seven patients from five unrelated families were recorded (four men and three women). Median age at diagnosis was 3.5 years. All patients had consanguineous parents. Six patients presented umbilical bleeding and only three patients had intracranial bleeding. Other bleeding features were seen, including skin and mucosal bleeding, muscular hematoma, and splenic rupture. Recurrent abortions were observed in one patient. The standard screening tests were normal. Genetic analysis identified two mutations interesting the subunit A of factor XIII. All patients received transfusion of fresh frozen plasma monthly. One patient was died because of intracranial hemorrhage.Factor XIII deficiency is a rare bleeding disorder which frequently increases in areas with high consanguinity. In our study, we identified a founder mutation. The prognosis of the disorder is related to hemorrhagic complications especially to life-threatening intracranial bleeding. Prophylaxis consists of factor XIII concentrate or recombinant factor XIII. If these are unavailable, fresh frozen plasma may be used.

Merosin-deficient congenital muscular dystrophy with mental retardation and cerebellar cysts, unlinked to the LAMA2, FCMD, MEB and CMD1B loci, in three Tunisian patients.

We report three Tunisian patients affected by congenital muscular dystrophy with mental retardation and cerebellar cysts on cranial magnetic resonance imaging. The clinical features were characterized by hypotonia at birth, joint contractures associated with severe psychomotor retardation, absence of speech, inability to walk in three patients, but calf hypertrophy was noted only in two patients. Brain magnetic resonance imaging showed several cerebellar cysts and vermis hypoplasia in all of the patients. Abnormality of the white matter was present in two patients. The pattern of gyration was normal in all cases. Serum creatine kinase was elevated in all three cases and their muscle biopsy showed dystrophic changes compatible with congenital muscular dystrophy. The immunohistochemical analysis of the skeletal muscle revealed partial merosin deficiency, more pronounced for the N-terminal antibody. Linkage analysis excluded congenital muscular dystrophy loci on chromosomes 6q22, 9q31, 1p32 and 1q42. These patients constituted a particular form of congenital muscular dystrophy with a combination of severe motor delay, mental retardation, partial merosin deficiency and cerebellar cysts. Two patients showed white matter abnormalities on magnetic resonance imaging and hypertrophy of the calves. These cases, in addition to those reported previously, confirmed the large phenotypic variability in the group of secondary merosin deficiency congenital muscular dystrophy.

Contribution of immunological and genetic investigations to improve classification of patients with congenital muscular dystrophy.

OBJECTIVE: To minimize the uncertainty in clinical diagnosis and improve the classification of 14 Tunisian patients belonging to 12 families and affected with congenital muscular dystrophy (CMD). METHODS: Fourteen patients belonging to 12 unrelated families originating from the south of Tunisia and affected with CMD were clinically examined between 1990 and 2001 in the neurology service of Chu Habib Bourguiba, Sfax, Tunisia. Immunohistochemical and western blot analyses were used to explore protein expression in muscular biopsies and homozygosity mapping using microsatellite markers for the genetic study. These analyses were performed in the human molecular genetics laboratory. RESULTS: Among the patients tested with anti-merosin antibodies, 3 showed total laminin-a2 deficiency and the remaining patients showed partial laminin-a2 deficiency. All patients expressed normally a-sarcoglycan, b-dystroglycan and dystrophin except 2 showing reduction of expression in a-sarcoglycan and b-dystroglycan. Linkage analysis, performed for 8 families, was compatible with linkage to the LAMA2 gene for only 2. CONCLUSION: Our results showed that clinical and immunohistochemical analyses have allowed classification of only 3 patients, immunohistochemical and genotyping studies have contributed to the classification of 7 patients. In the remaining cases, there is no evident classification due to the lack of the genetic exploration. Our results also confirmed the broad spectrum of phenotypes associated with a defect in laminin-a2.

Molecular confirmation of founder mutation c.-167A>G in Tunisian patients with PMLD disease.

Pelizaeus Merzbacher disease and Pelizaeus Merzbacher like disease (PMLD) are hypomyelinating leucodystrophies of the central nervous system (CNS) with a very similar phenotype. PMD is an X-linked recessive condition caused by mutations, deletion duplication or triplication of the proteolipid protein 1 gene (PLP1). However, PMLD is a recessive autosomal hypomyelinating leukodystrophy caused by mutations of the GJC2 gene. In this study, we analyzed 5 patients belonging to 4 Tunisian families. Direct sequencing of GJC2 gene in all probands showed the same homozygous founder mutation c.-167A>G localized in the promoter region. We also generated two microsatellite markers GJC2 195GT and GJC2 76AC closed to the GJC2 gene to confirm the presence of a founder effect for this mutation. Haplotype study showed that the c.-167A>G promoter mutation occurred in a specific founder haplotype in Tunisian population. The identification of this founder mutation has important implications towards genetic counseling in relatives of these families and the antenatal diagnosis.

Mutations in LAMA2 and CAPN3 genes associated with genetic and phenotypic heterogeneities within a single consanguineous family involving both congenital and progressive muscular dystrophies.

LGMD (limb-girdle muscular dystrophy) and CMD (congenital muscular dystrophy) are two common forms of neuromuscular disorders which are distinguishable by their age of onset but with probably a similar underlying pathway. In the present study, we report immunohistochemical, Western-blot and genetic analyses in a large consanguineous Tunisian family with two branches, including seven patients sharing similar LGMD2 phenotype in one branch and one CMD patient in the other branch. Linkage analyses were compatible with the LGMD2A locus in one branch and the MDC1A (muscular dystrophy congenital type 1A) locus in the other branch. This result was supported by deficiency in merosin and calpain3 in the CMD patient and LGMD patients respectively. Mutation analysis revealed two distinct mutations: a c.8005delT frameshift deletion in exon 56 of the LAMA2 (laminin-α2) gene (MDC1A) was found in the CMD patient and a new homozygous mutation c.1536+1G>T in the donor splice site of intron 12 of the CAPN3 (calpain3) gene (LGMD2A) was found in the LGMD patients. RT-PCR (reverse transcription-PCR) performed on total RNA from a LGMD2A patient's muscle biopsy showed complete retention of intron 12 in CAPN3 cDNA, generating a PTC (premature termination codon) that potentially elicits degradation of the nonsense mRNA by NMD (nonsense-mediated mRNA decay). Our results indicate that mRNA analysis is necessary to clarify the primary effect of genomic mutations on splicing efficiency that alters mRNA processing and expression level.

Mutational analysis of the MECP2 gene in Tunisian patients with Rett syndrome: a novel double mutation.

Rett syndrome is a severe disorder characterized by loss of acquired skills after a period of normal development in infant girls. It is caused mainly by mutations in the MECP2 gene. In this study, we reported mutations in the MECP2 gene in 7 Tunisian patients with classic Rett syndrome. The results showed the presence of a double mutation in 1 patient: p.R306C and c.1461+98insA, which create a new hypothetical polyadenylation site in the 3(')UTR of the MECP2 gene. We also detected in another patient a new variant c.1461+92C>G in the 3(')UTR located previous to 34 bp from the polyadenylation site with a score of 4.085. This variation is located in a hypothetical splicing enhancer with a score of 1.96277 according to the ESE finder program. In the remaining 5 patients, we found 2 common mutations: p.T158M in 4 individuals and p.R168X in only 1 girl.

Whole mitochondrial genome screening in two families with hearing loss: detection of a novel mutation in the 12S rRNA gene.

Sensorineural hearing loss has been described in association with different mitochondrial multisystemic syndromes, often characterized by an important neuromuscular involvement. Until now, mutations in mitochondrial DNA, especially in the 12S rRNA, the tRNASer(UCN) and the tRNALeu(UUR) genes, were implicated in syndromic or non-syndromic hearing loss either as a primary cause or as predisposing factors. In the present study, we performed a whole mitochondrial genome screening in two unrelated Tunisian families with inherited hearing loss. Results showed the presence of a novel mutation in the mitochondrial 12S rRNA gene in the two probands of these two families who belong to two different haplogroups: L3 and H6a1. The m.735A>G mutation affects a conserved nucleotide of the mitochondrial 12S rRNA gene in primates and other species and had a conservation index of 78.5% (11/14). We also detected known polymorphisms and sic novel mitochondrial variants. The present study confirmed that the mitochondrial 12S rRNA gene is a hot spot for mutations associated with hearing impairment.

The first genome-wide scan in a tunisian family with generalized epilepsy with febrile seizure plus (GEFS+).

Generalized epilepsy with febrile seizure plus (GEFS+) is an autosomal dominant disorder. In the literature, 5 responsible genes were identified and 2 novel susceptibility loci for GEFS+ at 2p24 and 8p23-p21 were reported, indicating the genetic heterogeneity of this disorder. The aim of this report is to identify the responsible loci in a large affected Tunisian family by performing a 10cM density genome-wide scan. The highest multipoint logarithm of odds (LOD) score (1.04) was found for D5S407 in the absence of recombination. Two other interesting regions were found around marker D19S210 (LOD=0.799) and D7S484 (LOD=0.61) markers. To fine map these loci, additional markers in 2 regions on 5q13.3 and 7p14.2 were analyzed and positive LOD scores for both loci were obtained. Sequencing of the Sodium channel subunit beta-1 gene (SCN1B) (19q13.1) showed the absence of any causal mutation. Our findings emphasized the genetic heterogeneity of febrile seizures.

Mutational analysis of the mitochondrial 12S rRNA and tRNASer(UCN) genes in Tunisian patients with nonsyndromic hearing loss.

We explored the mitochondrial 12S rRNA and the tRNASer(UCN) genes in 100 Tunisian families affected with NSHL and in 100 control individuals. We identified the mitochondrial A1555G mutation in one out of these 100 families and not in the 100 control individuals. Members of this family harbouring the A1555G mutation showed phenotypic heterogeneity which could be explained by an eventual nuclear-mitochondrial interaction. So, we have screened three nuclear genes: GJB2, GJB3, and GJB6 but we have not found correlation between the phenotypic heterogeneity and variants detected in these genes. We explored also the entire mitochondrial 12S rRNA and the tRNASer(UCN) genes. We detected five novel polymorphisms: T742C, T794A, A813G, C868T, and C954T, and 12 known polymorphisms in the mitochondrial 12S rRNA gene. None of the 100 families or the 100 controls were found to carry mutations in the tRNASer(UCN) gene. We report here the first mutational screening of the mitochondrial 12S rRNA and the tRNASer(UCN) genes in the Tunisian population which describes the second family harbouring the A1555G mutation in Africa and reveals novel polymorphisms in the mitochondrial 12S rRNA gene.

New FKRP mutations causing congenital muscular dystrophy associated with mental retardation and central nervous system abnormalities. Identification of a founder mutation in Tunisian families.

The congenital muscular dystrophies (CMD) constitute a clinically and genetically heterogeneous group of autosomal recessive myopathies. Patients show congenital hypotonia, muscle weakness, and dystrophic changes on muscle biopsy. Mutations in four genes (FKT1, POMGnT1, POMT1, FKRP) encoding putative glycosyltransferases have been identified in a subset of patients characterized by a deficient glycosylation of alpha-dystroglycan on muscle biopsy. FKRP mutations account for a broad spectrum of patients with muscular dystrophy, from a severe congenital form with or without mental retardation (MDC1C) to a much milder limb-girdle muscular dystrophy (LGMD2I). We identified two novel homozygous missense FKRP mutations, one, A455D, in six unrelated Tunisian patients and the other, V405L, in an Algerian boy. The patients, between the ages of 3 and 12 years, presented with a severe form of MDC1C with calf hypertrophy and high serum creatine kinase levels. None had ever walked. Two had cardiac dysfunction and one strabismus. They all had mental retardation, microcephaly, cerebellar cysts, and hypoplasia of the vermis. White matter abnormalities were found in five, mostly when cranial magnetic resonance imaging was performed at a young age. These abnormalities were shown to regress in one patient, as has been observed in patients with Fukuyama CMD. Identification of a new microsatellite close to the FKRP gene allowed us to confirm the founder origin of the Tunisian mutation. These results strongly suggest that particular FKRP mutations in the homozygous state induce structural and clinical neurological lesions in addition to muscular dystrophy. They also relate MDC1C to other CMD with abnormal protein glycosylation and disordered brain function.