Report on a Case with Moreno-Nishimura-Schmidt Overgrowth Syndrome: A Clinically Delineated Disease Yet of an Unknown Origin!

Introduction: Overgrowth syndromes are a heterogeneous group of genetic disorders characterized by excessive growth, often accompanied by additional clinical features, such as facial dysmorphism, hormonal imbalances, cognitive impairment, and increased risk for neoplasia. Moreno-Nishimura-Schmidt (M-N-S) overgrowth syndrome is a very rare overgrowth syndrome characterized by severe pre- and postnatal overgrowth, dysmorphic facial features, kyphoscoliosis, large hands and feet, inguinal hernia, and distinctive skeletal features. The clinical and radiological features of the disorder have been well delineated, yet its molecular pathogenesis remains unclear. Case Presentation: We report on a Lebanese boy with M-N-S syndrome, whose clinical manifestations were compared with those of previously reported 5 affected individuals. Whole-exome sequencing combined with comparative genome hybridization analysis failed to delineate the molecular basis of the phenotype. However, epigenetic studies revealed a different methylation status of several CpG sites between him and healthy controls, with methyltransferase activity showing the most significant enrichment. Conclusion: An additional case of M-N-S syndrome recapitulated the clinical and radiological manifestations described in the previous reports. The data in the epigenetic studies implicated that abnormal methylations might play an essential role in development of the disease phenotype. However, additional studies in a clinically homogeneous cohort of patients are crucial to confirm this hypothesis.

Imbalance of NRG1-ERBB2/3 signalling underlies altered myelination in Charcot-Marie-Tooth disease 4H.

Charcot-Marie-Tooth (CMT) disease is one of the most common inherited neurological disorders, affecting either axons from the motor and/or sensory neurons or Schwann cells of the peripheral nervous system (PNS) and caused by more than 100 genes. We previously identified mutations in FGD4 as responsible for CMT4H, an autosomal recessive demyelinating form of CMT disease. FGD4 encodes FRABIN, a GDP/GTP nucleotide exchange factor, particularly for the small GTPase Cdc42. Remarkably, nerves from patients with CMT4H display excessive redundant myelin figures called outfoldings that arise from focal hypermyelination, suggesting that FRABIN could play a role in the control of PNS myelination. To gain insights into the role of FGD4/FRABIN in Schwann cell myelination, we generated a knockout mouse model (Fgd4SC-/-), with conditional ablation of Fgd4 in Schwann cells. We show that the specific deletion of FRABIN in Schwann cells leads to aberrant myelination in vitro, in dorsal root ganglia neuron/Schwann cell co-cultures, as well as in vivo, in distal sciatic nerves from Fgd4SC-/- mice. We observed that those myelination defects are related to an upregulation of some interactors of the NRG1 type III/ERBB2/3 signalling pathway, which is known to ensure a proper level of myelination in the PNS. Based on a yeast two-hybrid screen, we identified SNX3 as a new partner of FRABIN, which is involved in the regulation of endocytic trafficking. Interestingly, we showed that the loss of FRABIN impairs endocytic trafficking, which may contribute to the defective NRG1 type III/ERBB2/3 signalling and myelination. Using RNA-Seq, in vitro, we identified new potential effectors of the deregulated pathways, such as ERBIN, RAB11FIP2 and MAF, thereby providing cues to understand how FRABIN contributes to proper ERBB2 trafficking or even myelin membrane addition through cholesterol synthesis. Finally, we showed that the re-establishment of proper levels of the NRG1 type III/ERBB2/3 pathway using niacin treatment reduces myelin outfoldings in nerves of CMT4H mice. Overall, our work reveals a new role of FRABIN in the regulation of NRG1 type III/ERBB2/3 NRG1signalling and myelination and opens future therapeutic strategies based on the modulation of the NRG1 type III/ERBB2/3 pathway to reduce CMT4H pathology and more generally other demyelinating types of CMT disease.

Case Report: Identification of Novel Variants in ERCC4 and DDB2 Genes in Two Tunisian Patients With Atypical Xeroderma Pigmentosum Phenotype.

Xeroderma Pigmentosum (XP) is a rare genetic disorder affecting the nucleotide excision repair system (NER). It is characterized by an extreme sensitivity to sunlight that induces cutaneous disorders such as severe sunburn, freckling and cancers. In Tunisia, six complementation groups have been already identified. However, the genetic etiology remains unknown for several patients. In this study, we investigated clinical characteristics and genetic defects in two families with atypical phenotypes originating from the central region in Tunisia. Clinical investigation revealed mild cutaneous features in two patients who develop multiple skin cancers at later ages, with no neurological disorders. Targeted gene sequencing revealed that they carried novel variants. A homozygous variation in the ERCC4 gene c.1762G>T, p.V588F, detected in patient XP21. As for patient XP134, he carried two homozygous mutations in the DDB2 gene c.613T>C, p.C205R and c.618C>A, p.S206R. Structural modeling of the protein predicted the identified ERCC4 variant to mildly affect protein stability without affecting its functional domains. As for the case of DDB2 double mutant, the second variation seems to cause a mild effect on the protein structure unlike the first variation which does not seem to have an effect on it. This study contributes to further characterize the mutation spectrum of XP in Tunisian families. Targeted gene sequencing accelerated the identification of rare unexpected genetic defects for diagnostic testing and genetic counseling.

A novel bi-allelic loss-of-function mutation in STIM1 expands the phenotype of STIM1-related diseases.

STIM1, the stromal interaction molecule 1, is the key protein for maintaining calcium concentration in the endoplasmic reticulum by triggering the Store Operated Calcium Entry (SOCE). Bi-allelic mutations in STIM1 gene are responsible for a loss-of-function in patients affected with a CRAC channelopathy syndrome in which severe combined immunodeficiency syndrome (SCID-like), autoimmunity, ectodermal dysplasia and muscle hypotonia are combined. Here, we studied two siblings from a consanguineous Syrian family, presenting with muscle weakness, hyperlaxity, elastic skin, tooth abnormalities, dysmorphic facies, hypoplastic patellae and history of respiratory infections. Using exome sequencing, we have identified a new homozygous frameshift mutation in STIM1: c.685delT [p.(Phe229Leufs*12)], leading to a complete loss of STIM1 protein. In this study, we describe an unusual phenotype linked to STIM1 mutations, combining clinical signs usually observed in different STIM1-related diseases. In particular, we confirmed that the complete loss of STIM1 function is not always associated with severe immune disorders. Altogether, our results broaden the spectrum of phenotypes associated with mutations in STIM1 and opens new perspectives on the pathological mechanisms associated with a defect in the proteins constituting the SOCE complex.

A severe clinical phenotype of Noonan syndrome with neonatal hypertrophic cardiomyopathy in the second case worldwide with RAF1 S259Y neomutation.

Noonan syndrome and related disorders are a group of clinically and genetically heterogeneous conditions caused by mutations in genes of the RAS/MAPK pathway. Noonan syndrome causes multiple congenital anomalies, which are frequently accompanied by hypertrophic cardiomyopathy (HCM). We report here a Tunisian patient with a severe phenotype of Noonan syndrome including neonatal HCM, facial dysmorphism, severe failure to thrive, cutaneous abnormalities, pectus excavatum and severe stunted growth, who died in her eighth month of life. Using whole exome sequencing, we identified a de novo mutation in exon 7 of the RAF1 gene: c.776C > A (p.Ser259Tyr). This mutation affects a highly conserved serine residue, a main mediator of Raf-1 inhibition via phosphorylation. To our knowledge the c.776C > A mutation has been previously reported in only one case with prenatally diagnosed Noonan syndrome. Our study further supports the striking correlation of RAF1 mutations with HCM and highlights the clinical severity of Noonan syndrome associated with a RAF1 p.Ser259Tyr mutation.

Identification of a ERCC5 c.2333T>C (L778P) Variant in Two Tunisian Siblings With Mild Xeroderma Pigmentosum Phenotype.

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder due to a defect in the nucleotide excision repair (NER) DNA repair pathway, characterized by severe sunburn development of freckles, premature skin aging, and susceptibility to develop cancers at an average age of eight. XP is an example of accelerated photo-aging. It is a genetically and clinically heterogeneous disease. Eight complementation groups have been described worldwide. In Tunisia, five groups have been already identified. In this work, we investigated the genetic etiology in a family with an atypically mild XP phenotype. Two Tunisian siblings born from first-degree consanguineous parents underwent clinical examination in the dermatology department of the Charles Nicolle Hospital on the basis of acute sunburn reaction and mild neurological disorders. Blood samples were collected from two affected siblings after written informed consent. As all mutations reported in Tunisia have been excluded using Sanger sequencing, we carried out mutational analysis through a targeted panel of gene sequencing using the Agilent HaloPlex target enrichment system. Our clinical study shows, in both patients, the presence of achromic macula in sun exposed area with dermatological feature suggestive of Xeroderma pigmentosum disease. No developmental and neurological disorders were observed except mild intellectual disability. Genetic investigation shows that both patients were carriers of an homozygous T to C transition at the nucleotide position c.2333, causing the leucine to proline amino acid change at the position 778 (p.Leu778Pro) of the ERCC5 gene, and resulting in an XP-G phenotype. The same variation was previously reported at the heterozygous state in a patient cell line in Europe, for which no clinical data were available and was suggested to confer an XP/CS phenotype based on functional tests. This study contributes to further characterization of the mutation spectrum of XP in consanguineous Tunisian families and is potentially helpful for early diagnosis. It also indicates that the genotype-phenotype correlation is not always coherent for patients with mild clinical features. These data therefore suggest that targeted NGS is a highly informative diagnostic strategy, which can be used for XP molecular etiology determination.

A novel PDE6D mutation in a patient with Joubert syndrome type 22 (JBTS22).

Joubert syndrome (JS) is an autosomal or X-linked recessive syndrome principally characterized by hypotonia, ataxia, cognitive impairment, and a specific finding on brain imaging called a "molar tooth sign" (MTS), which can be isolated or in conjunction with variable organ involvement. The genetic basis of JS is heterogeneous, with over 35 ciliary genes being implicated in its pathogenesis. However, some of these genes (such as PDE6D) have been associated to JS only in single families, seeking confirmation. Here we report a boy, born to first cousin parents, presenting with developmental delay, hypotonia, microcephaly, post axial polydactyly, oculomotor apraxia, and MTS. Whole exome sequencing revealed the presence of a novel homozygous truncating variant in the PDE6D gene: NM_002601.3:c.367_368insG [p.(Leu123Cysfs*13)]. The variant was confirmed by Sanger sequencing and found at the heterozygous state in both parents. A review of the literature pertaining to the role of PDE6D in JS is discussed.

Clinical profile of comorbidity of rare diseases in a Tunisian patient: a case report associating incontinentia pigmenti and Noonan syndrome.

BACKGROUND: Noonan syndrome (NS) is an autosomal dominant multisystem disorder caused by the dysregulation of several genes belonging to the RAS Mitogen Activated Protein Kinase (MAPK) signaling pathway. Incontinentia Pigmenti (IP) is an X-linked, dominantly inherited multisystem disorder. CASE PRESENTATION: This study is the first report of the coexistence of Noonan (NS) and Incontinentia Pigmenti (IP) syndromes in the same patient. We report on the clinical phenotype and molecular characterization of this patient. The patient was examined by a pluridisciplinary staff of clinicians and geneticist. The clinical diagnosis of NS and IP was confirmed by molecular investigations. The newborn girl came to our clinics due to flagrant dysmorphia and dermatological manifestations. The clinical observations led to characterize the Incontinentia Pigmenti traits and a suspicion of a Noonan syndrome association. Molecular diagnosis was performed by Haloplex resequencing of 29 genes associated with RASopathies and confirmed the NS diagnosis. The common recurrent intragenic deletion mutation in IKBKG gene causing the IP was detected with an improved PCR protocol. CONCLUSION: This is the first report in the literature of comorbidity of NS and IP, two rare multisystem syndromes.

Loss of Calmodulin- and Radial-Spoke-Associated Complex Protein CFAP251 Leads to Immotile Spermatozoa Lacking Mitochondria and Infertility in Men.

Flagella and motile cilia share a 9 + 2 microtubule-doublet axoneme structure, and asthenozoospermia (reduced spermatozoa motility) is found in 76% of men with primary ciliary dyskinesia (PCD). Nevertheless, causal genetic variants in a conserved axonemal component have been found in cases of isolated asthenozoospermia: 30% of men with multiple morphological anomalies of sperm flagella (MMAF) carry bi-allelic mutations in DNAH1, encoding one of the seven inner-arm dynein heavy chains of the 9 + 2 axoneme. To further understand the basis for isolated asthenozoospermia, we used whole-exome and Sanger sequencing to study two brothers and two independent men with MMAF. In three men, we found bi-allelic loss-of-function mutations in WDR66, encoding cilia- and flagella-associated protein 251 (CFAP251): the two brothers were homozygous for the frameshift chr12: g.122359334delA (p.Asp42Metfs∗4), and the third individual was compound heterozygous for chr12: g.122359542G>T (p.Glu111∗) and chr12: g.122395032_122395033delCT (p.Leu530Valfs∗4). We show that CFAP251 is normally located along the flagellum but is absent in men carrying WDR66 mutations and reveal a spermatozoa-specific isoform probably generated during spermatozoon maturation. CFAP251 is a component of the calmodulin- and radial-spoke- associated complex, located adjacent to DNAH1, on the inner surface of the peripheral microtubule doublets of the axoneme. In Tetrahymena, the CFAP251 ortholog is necessary for efficient coordinated ciliary beating. Using immunofluorescent and transmission electron microscopy, we provide evidence that loss of CFAP251 affects the formation of the mitochondrial sheath. We propose that CFAP251 plays a structural role during biogenesis of the spermatozoon flagellum in vertebrates.

VarAFT: a variant annotation and filtration system for human next generation sequencing data.

With the rapidly developing high-throughput sequencing technologies known as next generation sequencing or NGS, our approach to gene hunting and diagnosis has drastically changed. In <10 years, these technologies have moved from gene panel to whole genome sequencing and from an exclusively research context to clinical practice. Today, the limit is not the sequencing of one, many or all genes but rather the data analysis. Consequently, the challenge is to rapidly and efficiently identify disease-causing mutations within millions of variants. To do so, we developed the VarAFT software to annotate and pinpoint human disease-causing mutations through access to multiple layers of information. VarAFT was designed both for research and clinical contexts and is accessible to all scientists, regardless of bioinformatics training. Data from multiple samples may be combined to address all Mendelian inheritance modes, cancers or population genetics. Optimized filtration parameters can be stored and re-applied to large datasets. In addition to classical annotations from dbNSFP, VarAFT contains unique features at the disease (OMIM), phenotypic (HPO), gene (Gene Ontology, pathways) and variation levels (predictions from UMD-Predictor and Human Splicing Finder) that can be combined to optimally select candidate pathogenic mutations. VarAFT is freely available at: http://varaft.eu.

Rigid spine syndrome associated with sensory-motor axonal neuropathy resembling Charcot-Marie-Tooth disease is characteristic of Bcl-2-associated athanogene-3 gene mutations even without cardiac involvement.

INTRODUCTION: Bcl-2-associated athanogene-3 (BAG3) mutations have been described in rare cases of rapidly progressive myofibrillar myopathies. Symptoms begin in the first decade with axial involvement and contractures and are associated with cardiac and respiratory impairment in the second decade. Axonal neuropathy has been documented but usually not as a key clinical feature. METHODS: We report a 24-year-old woman with severe rigid spine syndrome and sensory-motor neuropathy resembling Charcot-Marie-Tooth disease (CMT). RESULTS: Muscle MRI showed severe fat infiltration without any specific pattern. Deltoid muscle biopsy showed neurogenic changes and discrete myofibrillar abnormalities. Electrocardiogram and transthoracic echocardiography results were normal. Genetic analysis of a panel of 45 CMT genes showed no mutation. BAG3 gene screening identified the previously reported c.626C>T, pPro209Leu, mutation. DISCUSSION: This case indicates that rigid spine syndrome and sensory-motor axonal neuropathy are key clinical features of BAG3 mutations that should be considered even without cardiac involvement. Muscle Nerve, 57: 330-334, 2018.

Neuroblastoma Amplified Sequence (NBAS) mutation in recurrent acute liver failure: Confirmatory report in a sibship with very early onset, osteoporosis and developmental delay.

BACKGROUND: Recently, biallelic mutations in the Neuroblastoma Amplified Sequence NBAS gene have been identified in ten patients that present recurrent acute liver failure (RALF) in early infancy. In addition to severe liver dysfunction, some of these individuals also suffered from other comorbidities including cardiomyopathy, neurologic phenotypes and gastrointestinal immune defects. Here we report on a consanguineous Lebanese family with three siblings affected by RALF. Of note, neonatal spontaneous fractures, developmental delay, prominent eyes, generalized hirsutism, gum hypertrophy, and hepato-splenomegaly ​were also present. METHODS: Whole-genome SNP genotyping in all the patients, followed by exome sequencing was performed in one of the affected siblings. RESULTS: A homozygous c.409C > T (p.Arg137Trp) missense mutation in NBAS was identified in all patients. CONCLUSION: Overall, our findings confirm the involvement of NBAS in the pathogenesis of this condition characterized by severe liver dysfunction and help expand its phenotypical spectrum.

WDR73 Mutations Cause Infantile Neurodegeneration and Variable Glomerular Kidney Disease.

Infantile-onset cerebellar atrophy (CA) is a clinically and genetically heterogeneous trait. Galloway-Mowat syndrome (GMS) is a rare autosomal recessive disease, characterized by microcephaly with brain anomalies including CA in some cases, intellectual disability, and early-infantile-onset nephrotic syndrome. Very recently, WDR73 deficiency was identified as the cause of GMS in five individuals. To evaluate the role of WDR73 mutations as a cause of GMS and other forms of syndromic CA, we performed Sanger or exome sequencing in 51 unrelated patients with CA and variable brain anomalies and in 40 unrelated patients with a diagnosis of GMS. We identified 10 patients from three CA and from two GMS families with WDR73 mutations including the original family described with CA, mental retardation, optic atrophy, and skin abnormalities (CAMOS). There were five novel mutations, of which two were truncating and three were missense mutations affecting highly conserved residues. Individuals carrying homozygous WDR73 mutations mainly presented with a pattern of neurological and neuroimaging findings as well as intellectual disability, while kidney involvement was variable. We document postnatal onset of CA, a retinopathy, basal ganglia degeneration, and short stature as novel features of WDR73-related disease, and define WDR73-related disease as a new entity of infantile neurodegeneration.

The impairment of MAGMAS function in human is responsible for a severe skeletal dysplasia.

Impairment of the tightly regulated ossification process leads to a wide range of skeletal dysplasias and deciphering their molecular bases has contributed to the understanding of this complex process. Here, we report a homozygous mutation in the mitochondria-associated granulocyte macrophage colony stimulating factor-signaling gene (MAGMAS) in a novel and severe spondylodysplastic dysplasia. MAGMAS, also referred to as PAM16 (presequence translocase-associated motor 16), is a mitochondria-associated protein involved in preprotein translocation into the matrix. We show that MAGMAS is specifically expressed in trabecular bone and cartilage at early developmental stages and that the mutation leads to an instability of the protein. We further demonstrate that the mutation described here confers to yeast strains a temperature-sensitive phenotype, impairs the import of mitochondrial matrix pre-proteins and induces cell death. The finding of deleterious MAGMAS mutations in an early lethal skeletal dysplasia supports a key role for this mitochondrial protein in the ossification process.

A novel mutation in FGD4/FRABIN causes Charcot Marie Tooth disease type 4H in patients from a consanguineous Tunisian family.

Charcot-Marie-Tooth (CMT) disease constitutes a clinically and genetically heterogeneous group of hereditary neuropathies characterized by progressive muscular and sensory loss in the distal extremities with chronic distal weakness, deformation of the feet, and loss of deep tendon reflexes. CMT4H is an autosomal recessive demyelinating subtype of CMT, due to mutations in FGD4/FRABIN, for which nine mutations are described to date. In this study, we describe three patients from a consanguineous Tunisian family, presenting with severe, early onset, slowly progressive, autosomal recessive demyelinating CMT, complicated by mild to severe kyphoscoliosis, consistent with CMT4H. In these patients, we report the identification of a novel homozygous frameshift mutation in FGD4: c.514_515insG; p.Ala172Glyfs*27. Our study reports the first mutation identified in FGD4 in Tunisian patients affected with CMT. It further confirms the important clinical heterogeneity observed in patients with mutations in FGD4 and the lack of phenotype/genotype correlations in CMT4H. Our results suggest that FGD4 should be screened in other early-onset CMT subtypes, regardless of the severity of the phenotype, and particularly in patients of consanguineous descent. In Tunisians, as in other populations with high consanguinity rates, screening of genes responsible for rare autosomal recessive CMT subtypes should be prioritized.

A novel MYH7 mutation links congenital fiber type disproportion and myosin storage myopathy.

This study aimed to identify the genetic defect in a multigenerational family presenting an autosomal dominant myopathy with histological features of congenital fiber type disproportion. Linkage analysis and genetic sequencing identified, in all affected members of the family, the c.5807A>G heterozygous mutation in MYH7, which encodes the slow/ß-cardiac myosin heavy chain. This mutation causes skeletal but not cardiac involvement. Myosin heavy chain expression pattern was also characterized by immunohistochemistry, western blot and q-PCR in muscle biopsies from two patients aged 25 and 62, respectively. While only congenital fiber type disproportion was observed in the younger patient, older patient's biopsy presented aggregates of slow myosin heavy chains, in fiber sub-sarcolemmal region. These clinico-pathologic findings suggest a novel phenotype within the emerging group of hereditary myosin myopathies, which in this family presents typical characteristics of congenital fiber type disproportion in early stages and later evolves to myosin storage myopathy.

Mutations in TREM2 lead to pure early-onset dementia without bone cysts.

A genome-wide screen using 382 STR markers to localize and identify the gene implicated in early-onset dementia (EOD) without bone cysts in a Lebanese family with three affected subjects was conducted. A unique locus homozygous by descent at chromosome 6p21.2 locus was identified. Candidate genes were explored by fluorescent sequencing and the effect of the identified mutation was confirmed by qualitative and quantitative RT-PCR. The genetic analysis revealed a novel deletion, c.40+3delAGG, in the 5' consensus donor splice site in intron 1 of TREM2 gene which is known to be responsible for PLOSL (Polycystic Lipomembranous Osteodysplasia with Sclerosing Leukoencephalopathy) also designated as Nasu-Hakola disease. In silico analysis predicted a lower strength for the novel donor splice site. Qualitative RT-PCR revealed normal transcript while quantitative RT-PCR showed over twofold down-regulation of TREM2 transcripts. The expression profile of six genes SPP1, NEDD9, FSCN, BCL3, NFKBIA and CCL2 known as disrupted in TREM2-deficient samples was studied and showed same expression profile as TREM2-mutated samples except for CCL2 which was normally regulated. The significantly-reduced expression of TREM2 in our patients and the expression profiles of the six studied genes confirm a role for TREM2 in this distinct phenotype of EOD without bone cysts. To our knowledge, this is the first report of mutations in TREM2 causing a pure dementia.

Mutation in WNT10A is associated with an autosomal recessive ectodermal dysplasia: the odonto-onycho-dermal dysplasia.

Odonto-onycho-dermal dysplasia is a rare autosomal recessive syndrome in which the presenting phenotype is dry hair, severe hypodontia, smooth tongue with marked reduction of fungiform and filiform papillae, onychodysplasia, keratoderma and hyperhidrosis of palms and soles, and hyperkeratosis of the skin. We studied three consanguineous Lebanese Muslim Shiite families that included six individuals affected with odonto-onycho-dermal dysplasia. Using a homozygosity-mapping strategy, we assigned the disease locus to an ~9-cM region at chromosome 2q35-q36.2, located between markers rs16853834 and D2S353, with a maximum multipoint LOD score of 5.7. Screening of candidate genes in this region led us to identify the same c.697G-->T (p.Glu233X) homozygous nonsense mutation in exon 3 of the WNT10A gene in all patients. At the protein level, the mutation is predicted to result in a premature truncated protein of 232 aa instead of 417 aa. This is the first report to our knowledge of a human phenotype resulting from a mutation in WNT10A, and it is the first demonstration of an ectodermal dysplasia caused by an altered WNT signaling pathway, expanding the list of WNT-related diseases.

Familial Mediterranean fever in the Syrian population: gene mutation frequencies, carrier rates and phenotype-genotype correlation.

BACKGROUND: Familial Mediterranean fever (FMF) is an autosomal recessive disease mainly affecting particularly Arabs, Non-Ashkenazi Jews, Armenians, and Turks. It is an autoinflammatory periodic disorder characterized by febrile and painful attacks due to inflammation involving the serosal membranes in the abdomen, chest or joints. Over 50 mutations have been identified in the MEFV gene responsible for FMF. OBJECTIVE: To identify the distribution and the frequency of the MEFV gene mutations in Syrian FMF patients and population and perform a genotype/phenotype correlation in the patients' cohort. PATIENTS AND METHODS: The study was carried out on 83 clinically diagnosed Syrian FMF patients and 242 healthy subjects. The tested individuals were screened for the most common five MEFV mutations (M694V, M694I, M680I, V726A and E148Q) by restriction fragment length polymorphism. Sequencing of exon 10 was performed only for the patients' DNA where just one or no mutation was detected. RESULTS AND DISCUSSION: Of the 83 patients studied, 74 (89%) were positive either for one, two or three mutations and nine (11%) had no mutations detected. Of those positive for mutations, 25 were homozygous, 30 were compound heterozygotes, three had complex alleles, and 16 patients had only one mutation. The M694V, V726A, M694I, M680I and E148Q mutations accounted for 45.8%, 26%, 13.9%, 4.8% and 6% of the alleles, respectively. The carrier rate in the Syrian population for the tested mutations was 17.5%, E148Q being the most common mutation, followed by V726A and M694V. The severity of the disease and development of amyloidosis seem to have an association with M694V, the most common mutation in Syrian FMF patients.

Molecular study of WISP3 in nine families originating from the Middle-East and presenting with progressive pseudorheumatoid dysplasia: identification of two novel mutations, and description of a founder effect.

Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive syndrome characterized by the presence of spondyloepiphyseal dysplasia associated with pain, stiffness, and swelling of multiple joints, osteoporosis, and the absence of destructive bone changes. The disorder is caused by mutations of the WISP3 gene located on chromosome 6q22. We hereby report the molecular study of the WISP3 gene in nine unrelated consanguineous families originating from the Middle-East: three from Lebanon, five from Syria, and one from Palestinian Bedouin descent, all affected with PPD. Five different sequence variations were identified in the WISP3 gene, two of them being new mutations: the c.589G --> C transversion at codon 197, responsible for a splicing defect (A197fsX201); and the c.536_537delGT deletion (C179fsX), both in exon 3. In all other families, the affected patients were homozygous for a previously described nonsense mutation, namely c.156C --> A (C52X). Interestingly, in the latter families, the C52X mutation was always found associated with a novel c.248G --> A (G83E) variation, suggesting the existence of a founder effect.