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M Shohat

Publications and source records attributed to M Shohat.

At least 55 records · Page 3Linked to original sources
PubMed1999

Phenotype-genotype correlation in familial Mediterranean fever: evidence for an association between Met694Val and amyloidosis.

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterised by recurrent attacks of inflammation of serosal membranes. Amyloidosis is the most severe complication of the disease. The aim of this study was to investigate the genotype-phenotype correlation and specifically the association between amyloidosis and the four common mutations in exon 10 of the gene causing FMF (MEFV) in a total of 83 FMF families from three ethnic groups: North African Jews, Armenians and Turks. A significant association was found between amyloidosis and the specific mutation at the MEFV gene: Met694Val (RR = 1.41, P = 0.02). Amyloidosis was present in 18 out of 87 homozygous FMF patients (20.7%) and in only two out of the 41 compound heterozygous FMF patients (4.9%). No patients carrying other mutations had amyloidosis. There was no significant association between the various mutations and the type or severity of the FMF symptoms. This finding underscores the importance of performing molecular studies on all suspect FMF patients. In addition to providing accurate diagnosis, these tests allow identification of presymptomatic genetically affected individuals, detection of carriers and assessment of the risk for amyloidosis in later life.

Adolescent↗
PubMed1999

A novel allele in the promoter region of the human serotonin transporter gene.

The human serotonin transporter (hSERT) gene is a promising candidate for mediating the genetic susceptibility for various psychiatric conditions such as mood and obsessive-compulsive disorders. Two polymorphic sites in this gene attracted much interest: a VNTR of 17-bp repeats in intron two, and an insertion/deletion in the 5'-flanking promoter region (5-HTT gene-linked polymorphic region-5-HTTLPR) creating a short (S) and a long (L) allele. The 5-HTTLPR polymorphism is situated in a GC-rich region composed of 20-23 bp repeating units. The S and L alleles have 14 and 16 repeat-elements respectively. Positive associations of the 5-HTTLPR polymorphism with mood disorders, anxiety-related personality traits, autism and late-onset Alzheimer's disease have been published, although some non replications were also reported. Here we report a novel allele (termed LJ) in the 5-HTTLPR site. This allele is longer than the L allele by 43 bp, has 18 repeat units and contains two copies of the insertion/deletion sequence arranged in tandem. The LJ allele was found in individuals of Libyan and Tunisian Jewish origin but not in Moroccan or Ashkenazi Jews.

Base Composition↗
PubMed1999

Evidence for the cofactor role of human T-cell lymphotropic virus type 1 in mycosis fungoides and Sézary syndrome.

The aetiology of mycosis fungoides (MF) and Sézary syndrome (SS) is unknown. A pathogenic role for the human T-cell lymphotropic virus type 1 (HTLV-1) has been suggested but remains controversial. We used an animal model to test the possibility that peripheral blood mononuclear cells (PBMC) obtained from MF patients harbour the HTLV-1 virus which may be infective. The polymerase chain reaction (PCR) was used to detect HTLV-1 proviral DNA sequences in PBMC of 27 MF patients and one SS patient of non-Iranian origin. Positive results were found in six of the patients. Twelve of the 28 patients tested by Western blot showed HTLV-1 antibodies. Twenty-eight immunosuppressed inbred Fisher F344 rats were inoculated intravenously with cultures of PBMC obtained from the 28 patients. Eight of these 28 rats showed antibodies to HTLV-1 while the proviral genome was demonstrated in the blood of only two of the rats. PBMC from two MF patients, in spite of showing negative results for the proviral genome by PCR, still induced HTLV-1 antibody formation in the F344 rat model. None of 10 control rats inoculated with normal donor PBMC showed antibodies to HTLV-1, nor the proviral genome. The present study suggests that HTLV-1 plays a cofactor role in MF/SS patients.

Adoptive Transfer↗
PubMed1999

Atopic dermatitis and HTLV-1-associated myelopathy: associated or coincidental disorders?

Reports from Jamaica have indicated that some patients with infective dermatitis or atopic dermatitis (AD) are seropositive for antibodies to human T-lymphotropic virus type 1 (HTLV-1). We describe a 32-year-old Israeli woman with long-term AD and paresthesia in the distal parts of the extremities. Neurological examination revealed a positive Babinski's sign. HLA typing demonstrated that this patient has the common HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and infective dermatitis haplotype for DRB1* DQB1*. The presence of HTLV-1 was demonstrated with polymerase chain reaction; HTLV-1-antibodies were detected by the Western blot method and by inoculation of the patient's peripheral blood mononuclear cells into F344 rats. This study confirms the presence of HTLV-1 antibodies and proviral genome in a patient with AD which later evolved into HAM/TSP. We cannot yet conclude whether these two diseases are associated or coincidental disorders.

Adult↗
PubMed1999

Growth, puberty, and endocrine functions in patients with sporadic or familial neurofibromatosis type 1: a longitudinal study.

OBJECTIVE: This study prospectively evaluates parameters of growth, puberty, and attained adult height in children with sporadic or familial occurrence of neurofibromatosis type 1 (NF-1), followed up longitudinally, to define the most important factors affecting these parameters. PATIENTS AND METHODS: The study was made up of 89 patients (55 boys, 34 girls) with sporadic (n = 45) or familial NF-1 (13 affected fathers and 31 affected mothers). The average age at referral was 8.9 years (range 8.5-15 years), and the average follow-up period was 8.5 years (6-15 years). A total of 28 patients attained adult height at the time of the report. Anthropometric measurements and bone age determinations were performed at 6- to 12-month intervals. As indicated, central nervous system (CNS) imaging was performed on 60 patients. Serum levels of thyroid stimulating hormone, free T4, lutheinizing hormone, follicle stimulating hormone, testosterone or estradiol, cortisol, and prolactin were measured in all patients periodically, and the pituitary growth hormone reserve was assessed in 32 short patients. RESULTS: CNS pathology was found in 23 of the 89 patients. A total of 6 patients required neurosurgery, and 2 patients had cranial irradiation. Of these patients, 3 were receiving recombinant growth hormone and thyroxin replacement therapy and 5 patients with precocious puberty were treated with a gonadotropin-releasing hormone analog. All other patients had normal endocrine tests. Precocious puberty was recorded in 5 patients and was more common among the familial cases. The 5 patients with precocious puberty also had CNS pathology. Short stature (<10th percentile) was observed in 25.5% of the patients during the prepubertal period with a significant gradual reduction of their relative height for age (standard scores) during puberty. Short adult height was noted in 12 (43%) of 28 patients, and only 50% of the 28 patients attained an adult height that was appropriate for their respective target height. Short stature was more common among patients with familial NF-1, particularly if the father was affected, and among those patients with CNS pathology. Parental short stature was observed in 39% of the mothers and in 33% of the fathers (59% and 54% among the affected parents, respectively). Tall stature (>90th percentile) was observed in 4 of 89 patients (4.5%), who all had CNS tumors. A highly significant correlation was found among all adult height-predicting parameters (r =.79), and attained adult height was best correlated with the target height (r =.7; n = 28). CONCLUSIONS: Short adult height is an important characteristic of NF-1 and deserves to be emphasized in the evaluation and follow-up of these patients during childhood. Short adult height is strongly linked with familial background of NF-1, in particular if the affected parent is the father, and is affected adversely by the relatively poor pubertal growth. Despite normal pituitary gland and thyroid function tests in most children and adolescents with NF-1, increased incidence of precocious puberty was observed. As the clinical expression in the second generation is more pronounced, the underlying mechanism seems to be mediated by genetic factors that are yet undefined.

Adolescent↗
PubMed1999

Pharyngeal flap for velopharyngeal incompetence in patients with myotonic dystrophy.

Velopharyngeal incompetence (VPI) has been associated with neuromuscular disorders. Only 4 patients with myotonic dystrophy (MD) who underwent pharyngeal flap elevation for VPI have been reported in the literature. In 3 patients, surgery preceded the diagnosis of MD. Cardiorespiratory complications characterized the postoperative period of 3 patients. The authors present 3 patients with VPI and an established diagnosis of MD (by molecular genetics) who underwent pharyngeal flap elevation. The operation resulted in a major improvement in speech in all patients, although some relapse was noted later in 1 patient. Contrary to previous reports, none had peri- or postoperative cardiorespiratory complications. MD, although an uncommon etiology, should be considered in cases of late-onset VPI. Owing to differences between the authors' findings and previous reports, additional studies are needed before final conclusions can be reached regarding the benefit and safety of pharyngeal flap surgery in MD patients. At present, MD should not be considered a contraindication for this procedure, although close perioperative monitoring is indicated.

Adult↗
PubMed1998

Correlation of linkage data with phenotype in eight families with Stickler syndrome.

The clinical findings of eight families with Stickler syndrome were analyzed and compared with the results of linkage studies using a marker for the type II collagen gene (COL2A1). In six families, there was linkage of the phenotype to COL2A1. The manifestations of the affected individuals were similar to those of the original Stickler syndrome family [Stickler et al., Mayo. Clin. Proc. 40:433-455, 1965] and resembled the phenotype of the previously reported individuals or families with Stickler syndrome in which a dominant mutation in the COL2A1 gene has been identified. Linkage to COL2A1 was excluded in the two remaining families. The most striking difference between these two types of families was the absence of severe myopia and retinal detachment in the two unliked families. In the COL2A1 unlinked families, linkage of the phenotype to genes (COL11A1 and COL11A2) that encode pro alpha chains of type XI collagen, a minor cartilage-specific collagen, was also excluded. Since Stickler syndrome can be produced by mutations in COL2A1, COL11A1, and COL11A2, our data suggest that there is at least a fourth locus for Stickler syndrome.

Collagen↗
PubMed1998

Evidence for complex nuclear inheritance in a pedigree with nonsyndromic deafness due to a homoplasmic mitochondrial mutation.

The relationship between mitochondrial genotype and clinical phenotype is complicated in most instances by the heteroplasmic nature of pathogenic mitochondrial mutations. We have previously shown that maternally inherited hearing loss in a large Arab-Israeli kindred is due to the homoplasmic A1555G mutation in the mitochondrial 12S ribosomal RNA gene [Prezant et al., 1993: Nat Genet 4:289-294]. Family members with this mutation have phenotypes ranging from profound hearing loss to completely normal hearing, and we have shown that there is genetic and biochemical evidence for nuclear gene involvement in this family [Bu et al., 1993: Genet Epidemiol 9:27-44; Guan et al., 1996: Hum Mol Genet 5:963-971]. To identify such a nuclear locus, two candidate genes were excluded through linkage analysis and sequencing, and a genome-wide linkage search in family members who all have the identical homoplasmic mitochondrial mutation, but differ in their hearing status, was performed. In two stages a total of 560 polymorphic genetic markers was genotyped, and the data were analyzed under model-dependent and model-free assumptions. No chromosomal region was identified as a major contributor to the phenotypic expression of the mitochondrial mutation. Thus, in this simplified paradigm of a homoplasmic mitochondrial mutation in a single kindred who all live in the similar environment of a small village, the penetrance of the mitochondrial mutation appears to depend on the interaction of multiple nuclear genes.

Chromosome Mapping↗
PubMed1998

Genetic influence on the prevalence of torus palatinus.

Torus palatinus (TP) represents a benign anatomic variation. It has been suggested that genetic factors play a leading role in its occurrence. The purpose of the present study was to determine, by segregation analysis, the inheritance of TP. Data were collected from members of 37 randomly selected Israel Jewish families and analyzed using the segregation analysis. Vertical transmission of TP was found in 19 families suggesting autosomal dominant transmission, which was supported by the results of the segregation analysis test. A significantly higher number of affected offspring (60.3%) was observed compared to the expected figure (50%) for an autosomal dominant trait with full penetrance. This is explained by the high gene frequency of TP and the relatively high proportion of homozygous parents.

Adult↗
PubMed1998

Assessment of pyrin gene mutations in Turks with familial Mediterranean fever (FMF).

Familial Mediterranean fever (FMF) is an autosomal recessive disease clinically characterized by recurrent short self-limited attacks of fever accompanied by peritonitis, pleurisy, and arthritis and can lead to amyloidosis and renal failure in the longer term. It is prevalent mainly in non-Ashkenazi Jews, Armenians, Turks, and Arabs. Due to the lack of an accurate diagnostic test, patients often experience years of attacks and invasive diagnostic procedures before the correct diagnosis is made and adequate treatment is begun. Recently, the gene responsible for FMF, denoted pyrin, has been cloned, and three disease mutations have been described (French FMF Consortium, 1997; International FMF Consortium, 1997). In the current study we assessed the spectrum of mutations in this gene in 16 unrelated families of Turkish origin. The three previously reported missense mutations (Met-Ile at codon 680, Met-Val at codon 694, and Val-Ala at codon 726) accounted for 29 of the 34 disease alleles. In one patient in whom no disease mutation was identified, the clinical picture was atypical enough to raise questions regarding the diagnosis. These results imply that the origin of FMF in Turkey is heterogeneous, that molecular diagnosis of FMF is possible in the majority of cases and clinically helpful, and that delineation of the undiscovered disease mutation(s) in the remaining cases remains a high priority.

Armenia↗
PubMed1998

Prevalence of glucocerebrosidase mutations in the Israeli Ashkenazi Jewish population.

Gaucher disease is the most prevalent inherited disease among Ashkenazi Jews. It is very heterogeneous due to a large number of mutations within the glucocerebrosidase gene, whose impaired activity is the cause for this disease. Aiming at determining Gaucher carrier frequency among the Ashkenazi Jewish population in Israel, 1,208 individuals were molecularly diagnosed for six mutations known to occur among Ashkenazi Jewish Gaucher patients, using the newly developed Pronto Gaucher kit. The following mutations were tested: N370S, 84GG, IVS2+1, D409H, L444P, and V394L. Molecular testing of these mutations also allows identification of the recTL allele. The results indicated that Gaucher carrier frequency is 1:17 within the tested population. The prevalence of N370S carriers is 1:17.5. This implies that approximately 1:1225 Ashkenazi Jews will be homozygous for the N370S mutation. Actually, in our study of 1,208 individuals one was found to be homozygous for the N370S mutation. The actual number of known Ashkenazi Jewish Gaucher patients with this genotype is much lower than that expected according to the frequency of the N370S mutation, suggesting a low penetrance of this mutation. Results of loading experiments in cells homozygous for the N370S mutation, as well as cells homozygous for the L444P and the D409H mutations, exemplified this phenomenon.

Cells, Cultured↗
PubMed1998

Amyloidosis in familial mediterranean fever is associated with a specific ancestral haplotype in the MEFV locus.

Familial Mediterranean fever (FMF) is a recessive disease characterized by recurrent attacks of inflammation of serosal membranes, and the gene responsible, MEFV, has been recently identified. Amyloidosis is considered to be the most severe complication. Since colchicine is effective in preventing FMF amyloidosis and since this process can develop even prior to the FMF symptoms, lifelong colchicine treatment is recommended for all FMF patients. Identification of the factor which determines amyloidosis will allow treatment to be directed only to those at risk. In order to investigate the association between amyloidosis and MEFV haplotypes, we studied 56 families from three ethnic groups. We compared the haplotypes of FMF patients with and without amyloidosis in each ethnic group separately and identified 14 different MEFV core haplotypes. A significant association (P < 0.004) was found between amyloidosis and a specific core haplotype, 153bp:104bp at markers D16S3370 and D16S2617, respectively. Amyloidosis was present in 20 out of 70 homozygotes for this haplotype and in 6 out of 35 compound heterozygotes for this and other core haplotypes. None of the patients who did not carry this allele had amyloidosis. There was no association between the various haplotypes and severity of the FMF symptoms, age of onset, or age at commencement of colchicine. Further investigation of the MEFV haplotypes in additional patients is recommended as such an association may save many mildly affected or asymptomatic patients with non-amyloidotic genotypes from receiving unnecessary lifelong colchicine treatment.

Adolescent↗
PubMed1998

Replication timing of the various FMR1 alleles detected by FISH: inferences regarding their transcriptional status.

Following the application of two-color fluorescence in-situ hybridization (FISH) to human interphase cells, we examined the replication timing of the fragile-X locus relative to the non-transcribed late replicating alpha-satellite region of chromosome-X, a built-in intracellular reference locus. In this assay, an unreplicated locus is identified by a single hybridization signal (singlet; S), whereas a replicated locus is identified by a duplicated signal (doublet; D). Hence, following simultaneous hybridization with the FMR1 and alpha-satellite probes, male cells with one singlet and one doublet signal per cell (SD cells) indicate S-phase cells where only one of the two loci has replicated. The studied cell samples (lymphocytes and amniocytes) were derived from normal males, fragile-X male patients, and premutation male carriers. Three distinct populations of SD cells were identified among the various samples. The first population had a high frequency of cells showing a doublet FMR1; this pattern, indicating early replication of FMR1, characterized the SD cell population of normal males. The second population had a high frequency of cells showing a singlet FMR1; this pattern, indicating very late replication of FMR1, characterized the SD population of fragile-X patients. The third population had about one half of the cells showing a singlet FMR1 and the other half with a doublet FMR1, indicating somatic variation in the replication timing of FMR1; this pattern was seen in the SD cell population of premutation carriers. The replication status of the FMR1 locus in the cells of patients was altered from late to early in the presence of 5-azadeoxycytidine, an activator of various silent genes. Based on the vast amount of information showing that expressed loci replicate early, whereas unexpressed loci replicate late, we inferred from the replication status of the FMR1 locus that: (1) the normal FMR1 allele is transcriptionally active in lymphocytes and amniocytes; (2) the fully mutated FMR1 allele is transcriptionally silent; (3) the transcriptional activity of the premutated allele is somewhat disturbed; (4) 5-azadeoxycytidine activates the fully mutated FMR1 allele.

Alleles↗
PubMed1998

Abnormal liver test results in myotonic dystrophy.

Myotonic dystrophy (DM) is an autosomal dominant multisystem disorder. Little evidence suggests the existence of liver damage in a small number of patients. We have prospectively evaluated liver and gallbladder function in 53 patients with DM in relation to clinical and genetic parameters. None of the patients had an enlarged liver, signs of cirrhosis, or portal hypertension. All were free of medication, and none were pregnant or had a history of alcohol abuse. In 35 (66%) patients, serum activity of at least one of six liver enzymes assayed was abnormal. An elevated level of alkaline phosphatase was found in 50.9%, of gamma-glutamyltransferase in 52.8%, of 5' nucleotidase in 43.4%, of serum aspartate aminotransferase in 35.8%, of serum alanine aminotransferase in 33.9%, and of lactate dehydrogenase in 37.7%. Liver function test results did not correlate with severity of muscle weakness, disease duration, or serum levels of creatine kinase, glucose, or lipids. Motility of gallbladder and abdominal ultrasonography were normal. Cytosine-thymidine-guanine repeat expansion by southern blot did not correlate with liver enzyme abnormalities. We conclude that elevation of liver enzymes is frequent in DM and should be included as an additional laboratory finding of the disease.

Blotting, Southern↗