Identification of a mutation in TNRC18 in a patient with clinical features of Fazio-Londe disease

Fazio-Londe disease and Brown-Vialetto-Van Laere syndrome are rare related neurological disorders. Although SLC52A3 and SLC52A2 that encode riboflavin transporters are their only known causative genes, many patients without mutations in these genes have been reported. Clinical and genetic data of a patient with features suggestive of Fazio-Londe disease are presented. Neurological examination revealed significant involvement of cranial nerves and weakness in the lower extremities. Pontobulbar presentations were prominent. EDX study suggested motor neuronopathy. Hearing was normal. She was diagnosed with FL disease. Response to riboflavin supplementation was not favorable. The patient's pedigree suggested recessive inheritance. SLC52A3 and SLC52A2 were screened and mutations were not observed. Results of exome sequencing and segregation analysis suggested that a mutation in TNRC18 is a candidate cause of disease in the patient. The three dimensional structure of the TNRC18 protein was predicted and it was noted that its two conserved domains (BAH and Tudor) interact and that the valine residue affected by the mutation is positioned close to both domains. A mutation in TNRC18 is cautiously reported as the possible cause of FL disease in the patient. The finding warrants further inquiries on TNRC18 about which little is presently known.

Iranian clinical practice guideline for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegeneration involving motor neurons. The 3-5 years that patients have to live is marked by day-to-day loss of motor and sometimes cognitive abilities. Enormous amounts of healthcare services and resources are necessary to support patients and their caregivers during this relatively short but burdensome journey. Organization and management of these resources need to best meet patients' expectations and health system efficiency mandates. This can only occur in the setting of multidisciplinary ALS clinics which are known as the gold standard of ALS care worldwide. To introduce this standard to the care of Iranian ALS patients, which is an inevitable quality milestone, a national ALS clinical practice guideline is the necessary first step. The National ALS guideline will serve as the knowledge base for the development of local clinical pathways to guide patient journeys in multidisciplinary ALS clinics. To this end, we gathered a team of national neuromuscular experts as well as experts in related specialties necessary for delivering multidisciplinary care to ALS patients to develop the Iranian ALS clinical practice guideline. Clinical questions were prepared in the Patient, Intervention, Comparison, and Outcome (PICO) format to serve as a guide for the literature search. Considering the lack of adequate national/local studies at this time, a consensus-based approach was taken to evaluate the quality of the retrieved evidence and summarize recommendations.

Identification of UBA1 as the causative gene of an X-linked non-Kennedy SBMA

BACKGROUND

Spinal-bulbar muscular atrophy (SBMA; Kennedy's Disease) is a motor neuron disease (MND). Kennedy's Disease is nearly exclusively caused by mutations in the androgen receptor encoding gene (AR). We report results of studies aimed at identification of the genetic cause of a disease that best approximates SBMA in a pedigree (four patients) without mutations in AR.

METHODS

Clinical investigations included thorough neurologic and non-neurologic examinations and testings. Genetic analysis was performed by exome sequencing using standard protocols. UBA1 mutations were modeled on the crystal structure of UBA1.

RESULTS

The clinical features of the patients are described in detail. A missense mutation in UBA1 (c.T1499C; p.Ile500Thr) was identified as the probable cause of the non-Kennedy SBMA in the pedigree. Like AR, UBA1 is positioned on Chromosome X. UBA1 is a highly conserved gene. It encodes ubiquitin like modifier activating enzyme 1 (UBA1) which is the major E1 enzyme of the ubiquitin-proteasome system. Interestingly, UBA1 mutations can also cause infantile-onset X-linked spinal muscular atrophy (XL-SMA). The mutation identified here and the XL-SMA causative mutations were shown to affect amino acids positioned in the vicinity of UBA1's ATP binding site and to cause structural changes.

CONCLUSION

UBA1 was identified as a novel SBMA causative gene. The gene affects protein homeostasis which is one of most important components of the pathology of neurodegeneration. The contribution of this same gene to the etiology of XL-SMA is discussed.

Identification of RNF13 as cause of recessively inherited ALS in a multi-case pedigree

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease. The approximately 50 known ALS-associated genes do not fully explain its heritability, which suggests the existence of yet unidentified causative genes. We report results of studies aimed at identification of the genetic cause of ALS in a pedigree (three patients) without mutations in the common ALS-causative genes.

METHODS

Clinical investigations included thorough neurological and non-neurological examinations and testings. Genetic analysis was performed by exome sequencing. Functional studies included identification of altered splicing by PCR and sequencing, and mutated proteins by western blot analysis. Apoptosis in the presence and absence of tunicamycin was assessed in transfected HEK293T cells using an Annexin-PE-7AAD kit in conjunction with flow cytometry.

RESULTS

Clinical features are described in detail. Disease progression in the patients of the pedigree was relatively slow and survival was relatively long. An RNF13 mutation was identified as the cause of the recessively inherited ALS in the pedigree. The gene is highly conserved, and its encoded protein (RING finger protein 13) can potentially affect various neurodegenerative-relevant functions, including protein homeostasis. The RNF13 splice site mutation caused expression of two mis-spliced forms of RNF13 mRNA and an aberrant RNF13 protein, and affected apoptosis.

CONCLUSION

RNF13 was identified as a novel causative gene of recessively inherited ALS. The gene affects protein homeostasis, which is one of most important components of the pathology of neurodegeneration. The contribution of RNF13 to the aetiology of another neurodegenerative disease is discussed.

Thigh and Leg Muscle MRI Findings in GNE Myopathy

BACKGROUND

Muscle MRI protocols have been developed to assess muscle involvement in a wide variety of muscular dystrophies. Different muscular dystrophies can involve muscle groups in characteristic patterns. These patterns can be identified in muscle MRI in the form of fatty infiltration.

OBJECTIVE

This study was conducted to add the existing knowledge of muscle MRI in GNE myopathy and evaluate the correlation of muscular involvement with different gene mutations.

METHODS

The MRI scans of the 18 GNE patients were analyzed retrospectively. Cluster analysis was done for grouping the muscles and patients.

RESULTS

The four muscles with the highest fat infiltration were adductor magnus, tibialis anterior, semitendinosus, and semimembranosus. Furthermore, three clusters of muscle involvement were found, including cluster 1, typical muscle involvement indicating muscles with the highest infiltration: extensor digitorum longus, gracilis, biceps femoris, soleus, gastrocnemius medial, adductor longus, tibialis anterior, adductor magnus, semimembranosus, semitendinosus; cluster 2, less typical muscle involvement indicating muscles with intermediate fat infiltration, peroneus longus, gastrocnemius lateral, and minimal fat infiltration in most of the patients, i.e., tibialis posterior; and cluster 3, atypical muscle involvement with low-fat infiltration: rectus femoris, sartorius, vastus intermedius, vastus medialis, and vastus lateralis.

CONCLUSIONS

This study found three clusters of muscle involvement and three groups of patients among GNE patients. Hamstring muscles and the anterior compartment of the lower leg were the muscles with the highest fat infiltration. Moreover, a weak genotype-muscle MRI association was found in which tibialis posterior was more involved in patients with the most frequent mutation, i.e., C.2228T > C (p.M743T) mutation; however, this finding may be related to longer disease duration.

A case of adult onset Sandhoff disease that mimics Brown-Vialetto-Van Laere syndrome

Sandhoff disease is a rare fatal infantile neurologic disorder. Adult onset Sandhoff is even rarer. Variability of clinical features in adult onset Sandhoff patients and overlaps between these and features of other neurologic diseases have sometimes led to mis-diagnosis. We describe an adult onset Sandhoff disease affected individual whose clinical presentation were also consistent with the Brown-Vialetto-Van Laere syndrome (BVVL) diagnosis. Screening of BVVL-causing genes, SLC52A3 and SLC52A2, did not identify candidate disease-causing mutations, but exome sequencing revealed compound heterozygous mutations in the known Sandhoff disease-causing gene, HEXB. Decreased blood hexosaminidase activity and evidence of cerebellar atrophy confirmed Sandhoff disease diagnosis. To the best of our knowledge, this is the first report of a Sandhoff disease case that mimics BVVL and that presents with prominent cranial nerve involvement. For differential diagnosis, measurement of hexosaminidase activity and MRI should quickly be performed. Genetic analysis can be done for confirmation of diagnosis.

BVVL/ FL: features caused by SLC52A3 mutations; WDFY4 and TNFSF13B may be novel causative genes

Brown-Vialetto-Van Laere (BVVL) and Fazio-Londe are disorders with amyotrophic lateral sclerosis-like features, usually with recessive inheritance. We aimed to identify causative mutations in 10 probands. Neurological examinations, genetic analysis, audiometry, magnetic resonance imaging, biochemical and immunological testings, and/or muscle histopathology were performed. Mutations in known causative gene SLC52A3 were found in 7 probands. More importantly, only 1 mutated allele was observed in several patients, and variable expressivity and incomplete penetrance were clearly noted. Environmental insults may contribute to variable presentations. Putative causative mutations in other genes were identified in 3 probands. Two of the genes, WDFY4 and TNFSF13B, have immune-related functions. Inflammatory responses were implicated in the patient with the WDFY4 mutation. Malfunction of the immune system and mitochondrial anomalies were shown in the patient with the TNFSF13B mutation. Prevalence of heterozygous SLC52A3 BVVL causative mutations and notable variability in expressivity of homozygous and heterozygous genotypes are being reported for the first time. Identification of WDFY4 and TNFSF13B as candidate causative genes supports conjectures on involvement of the immune system in BVVL and amyotrophic lateral sclerosis.

Deep geno- and phenotyping in two consanguineous families with CMT2 reveals HADHA as an unusual disease-causing gene and an intronic variant in GDAP1 as an unusual mutation

BACKGROUND

Charcot-Marie-Tooth (CMT) disease is a prevalent and heterogeneous peripheral neuropathy. Most patients affected with the axonal form of CMT (CMT2) do not harbor mutations in the approximately 90 known CMT-associated genes. We aimed to identify causative genes in two CMT2 pedigrees.

METHODS

Neurologic examination, laboratory tests and brain MRIs were performed. Genetic analysis included exome sequencing of four patients from the two pedigrees. The predicted effect of a deep intronic mutation on splicing was tested by regular and real-time PCR and sequencing.

RESULTS

Clinical data were consistent with CMT2 diagnosis. Inheritance patterns were autosomal recessive. Exome data of CMT2-101 did not include mutations in known CMT-associated genes. Sequence data, segregation analysis, bioinformatics analysis, evolutionary conservation, and information in the literature strongly implicated HADHA as the causative gene. An intronic variation positioned 23 nucleotides away from following intron/exon border in GDAP1 was ultimately identified as cause of CMT in CMT2-102. It was shown to affect splicing.

CONCLUSION

The finding of a HADHA mutation as a cause of CMT is of interest because its encoded protein is a subunit of the mitochondrial trifunctional protein (MTP) complex, a mitochondrial enzyme involved in long chain fatty acid oxidation. Long chain fatty acid oxidation is an important source of energy for skeletal muscles. The mutation found in CMT2-102 is only the second intronic mutation reported in GDAP1. The mutation in the CMT2-102 pedigree was outside the canonical splice site sequences, emphasizing the importance of careful examination of available intronic sequences in exome sequence data.

Description of combined ARHSP/JALS phenotype in some patients with SPG11 mutations

Background

SPG11 mutations can cause autosomal recessive hereditary spastic paraplegia (ARHSP) and juvenile amyotrophic lateral sclerosis (JALS). Because these diseases share some clinical presentations and both can be caused by SPG11 mutations, it was considered that definitive diagnosis may not be straight forward.

Methods

The DNAs of referred ARHSP and JALS patients were exome sequenced. Clinical data of patients with SPG11 mutations were gathered by interviews and neurological examinations including electrodiagnosis (EDX) and magnetic resonance imaging (MRI).

Results

Eight probands with SPG11 mutations were identified. Two mutations are novel. Among seven Iranian probands, six carried the p.Glu1026Argfs*4‐causing mutation. All eight patients had features known to be present in both ARHSP and JALS. Additionally and surprisingly, presence of both thin corpus callosum (TCC) on MRI and motor neuronopathy were also observed in seven patients. These presentations are, respectively, key suggestive features of ARHSP and JALS.

Conclusion

We suggest that rather than ARHSP or JALS, combined ARHSP/JALS is the appropriate description of seven patients studied. Criteria for ARHSP, JALS, and combined ARHSP/JALS designations among patients with SPG11 mutations are suggested. The importance of performing both EDX and MRI is emphasized. Initial screening for p.Glu1026Argfs*4 may facilitate SPG11 screenings in Iranian patients.

Phenotypic stratification and genotype-phenotype correlation in a heterogeneous, international cohort of GNE myopathy patients: First report from the GNE myopathy Disease Monitoring Program, registry portion

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Patient registry is a valuable tool in international GNE myopathy research.

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The registry expands the knowledge of GNE myopathy genetics and epidemiology.

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The registry allows monitoring of the disease progression and discovering diversity.

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The data suggest possible genotype–phenotype correlation in GNE myopathy.

GNE myopathy is a rare distal myopathy, caused by mutations in the GNE gene, affecting sialic acid synthesis. Clinical presentation varies from asymptomatic early stage patients to severely debilitating forms. This first report describes clinical presentations and severity of the disease, using data of 150 patients collected via the on-line, patient-reported registry component of the GNE Myopathy Disease Monitoring Program (GNEM-DMP). Disease progression was prospectively analysed, over a 2-year period, using the GNE myopathy functional activity scale (GNEM-FAS). The average annual rates of decline in function were estimated at −9.6% and −3.2% in ambulant and non-ambulant patients respectively. 4.3% of participants became non-ambulant within one year. The mean time from onset to required use of a wheelchair was 11.9 years. Mean delay of genetic diagnosis from symptom onset was 5.2 years. Mutation specific analysis demonstrated genotype–phenotype relationships; i.e. p.Ala662Val may be associated with a more severe phenotype, compared to p.Val727Met. Patients with compound heterozygous mutation in epimerase and kinase domain appeared to have a more severe phenotype compared to patients with both mutations located within one domain. Acknowledging the limitations of the study, these findings suggest that the severity of the GNE mutations affects disease severity. The GNEM-DMP is a useful data collection tool, prospectively measuring the progression of GNE myopathy, which could play an important role in translational and clinical research and further understanding of genotype–phenotype correlations.

Trends of quality of life changes in amyotrophic lateral sclerosis patients

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is an incurable progressive neurodegenerative disease and thus the assessment of quality of life (QOL) changes and factors that may influence its course is valuable in the meantime.

OBJECTIVES

The present study aimed to assess the deterioration rate of QOL and influencing factors in different subgroups of Iranian ALS patients.

METHODS

132 patients were evaluated in this prospective multicenter observational study. QOL was measured using ALS Assessment Questionnaire (ALSAQ-40) during 1year follow up and its progression rate was assessed in different subgroups of patients according to age, sex, stage of disease, riluzole consumption, onset type. Also physical disability and functional disability were measured using MMT and ALSFRS-R scores respectively and their progression rates were compared with ALSAQ-40 changes.

RESULTS

Significant deterioration of the scores of ALSAQ-40 during study was consistent in all of its domains (p=0.000). There was a significant negative correlation between ALSFRS-R and MMT changes and ALSAQ-40 change (p=0.000) and this was consistently observed in all domains of ALSAQ-40 (p=0.00). ALSAQ-40 deterioration rate was shown to be significantly lower in severe/terminal stages compared to mild/moderate stages (p=0.00). Significantly higher deterioration rate was observed in bulbar onset versus limb onset patients [F (1,130)=4.52, p=0.04] but no significant difference was observed among other subgroups according to age, sex and riluzole consumption.

CONCLUSION

All domains of QOL significantly deteriorate during ALS course and there is a significant correlation between their changes and progression of physical and functional disabilities. Rate of degradation of QOL may be different at different stages of the disease. QOL worsens independent of factors such as sex, age and consumption of riluzole; but onset type (bulbar versus limb) is an imperative factor in quality of life changes during the disease course.

Amyotrophic lateral sclerosis progression: Iran-ALS clinical registry, a multicentre study

This study was designed to evaluate ALS progression among different subgroups of Iranian patients. Three hundred and fifty-eight patients from centres around the country were registered and their progression rate was evaluated using several scores including Manual Muscle Test scoring (MMT) and the revised ALS Functional Rating Scale (ALSFRS-R). Progression rate was analysed separately in subgroups regarding gender, onset site, stage of disease and riluzole consumption. A significant difference in MMT deterioration rate (p = 0.01) was noted between those who used riluzole and those who did not. No significant difference was observed in progression rates between male/female and bulbar-onset/limb-onset groups using riluzole. In conclusion, riluzole has a significant effect on muscle force deterioration rate but not functional scale. Progression rate was not influenced by site of onset or gender.

Genetics of GNE myopathy in the non-Jewish Persian population

GNE myopathy is an autosomal recessive adult-onset disorder characterized by progressive muscle atrophy and weakness, initially involving the distal muscles, while often sparing the quadriceps. It is caused by variants in the GNE gene that encodes a key bifunctional enzyme in the sialic acid biosynthetic pathway. We investigated the clinical and molecular characteristics of 18 non-Jewish Persian patients from 11 unrelated GNE myopathy families. In addition, we reviewed the previously reported cases and suggest genotype-phenotype correlations for the identified variants. Comprehensive clinical and laboratory evaluations were carried out. Sequencing of the GNE gene was performed using genomic DNA from the patients. Screening of the identified variants was performed in all relevant family members. Molecular analyses identified three causative homozygous GNE variants in 11 families: c.2228T>C (p. M743T) in 7, c.830G>A (p.R277Q) in 2, and one novel variation (c.804G>A) in 2 families that results in a synonymous codon change (p.L268=) and likely creates a novel splice site affecting the protein function. This study confirms that c.2228T>C (p.M743T) is the most prevalent disease-causing variant in the non-Jewish Persian population, but other GNE variants can cause GNE myopathy in this population. The patients with all three different variants had similar ages of onset. The youngest patient was an 18-year-old girl in whom the c.830G>A (p.R277Q) variant was identified, whereas the oldest onset age (31 years) was seen in a male patient with c.804G>A (p.L268=). The results of this investigation expand our knowledge about the genotype-phenotype correlations in GNE myopathy and aid in clinical management and therapeutic interventions.

An Iranian familial amyotrophic lateral sclerosis pedigree with p.Val48Phe causing mutation in SOD1: a genetic and clinical report

OBJECTIVES

Amyotrophic lateral sclerosis (ALS), a fatal progressive neurodegenerative disorder, is the most common motor neuron disease in European populations. Approximately 10% of ALS cases are familial (FALS) and the other patients are considered as sporadic ALS (SALS). Among many ALS causing genes that have been identified, mutations in SOD1 and C9orf72 are the most common genetic causes of the disease. In Iranian patients, it has been shown that SOD1, as compared to C9orf72, plays a much more prominent role. To date, more than 170 mutations have been reported in SOD1. Genotype/phenotype correlation with respect to either different causative genes or different mutations of a specific gene has not been well established.

MATERIALS AND METHODS

Five exons of SOD1 and flanking intronic sequences of an Iranian FALS proband were screened for mutations by direct sequencing. Also, the clinical features of the proband were described.

RESULTS

Heterozygous p.Val48Phe causing mutation was identified in SOD1. Age at onset was 29 years and site of the first presentation was the lower extremity in the proband.

CONCLUSION

The p.Val48Phe causing mutation appears to cause early onset of ALS.

Clinicopathologic characteristics and outcome of childhood and adolescent Ewing's sarcoma in center of Iran

BACKGROUND

Ewing's sarcoma family is a group of small round cells tumors. The aim of this study is to evaluate clinicopathologic characteristics and outcome of Ewing's sarcoma in children and adolescents in Yazd, Iran.

MATERIALS AND METHODS

All patients under 19 years with documented pathology of Ewing's sarcoma family tumor who referred to Shahid Ramazanzadeh Radiotherapy center between 2002 to 2010 were enrolled in this retrospective study. Overall survival and disease free survival and prognostic factors were evaluated.

RESULTS

Among approximately 80,000 patients who referred to Shahid Sadoughi pathology department, over an 8-year period, the total number of patients with Ewing sarcoma was 32, of which, 18 cases were under the age 19 . The mean age was 13.72 years. Five patients (27.8%) had metastatic disease at the time of diagnosis. Complete response had been achieved in 8 (44.4%) of the patients. Local recurrence occurred in 4 (22.2%) of the patients. During the follow up 13 (72.2%) of the patients showed metastases. The mean overall survival was 34.79 months (95% CI: 22.27-47.32) .One, two, four and five year survival was 72%, 39%, 25% and 17% respectively. Complete remission occurred in 10 patients (63.6%). A trend of better overall survival was found in these patients (p=0. 55). When the brain and bone metastases occurred, the overall survival decreased significantly (p=0. 003 ).

CONCLUSIONS

The overall survival rate of Ewing's sarcoma is very low in comparison with other parts of the world.

Identification of mutation in NPC2 by exome sequencing results in diagnosis of Niemann-Pick disease type C

We report identification of a homozygous mutation in NPC2 in two Iranian siblings with a neurologic dysfunction whose disease had not been diagnosed prior to our genetic analysis. The mutation was identified by exome sequencing. The finding resulted in diagnosis of Niemann-Pick disease type C (NPC) in the siblings, and initiation of treatment with Miglustat. The clinical features of the patients are presented. It has been suggested that NPC is under diagnosed, particularly when presentations are not very severe, as was the situation in the cases studied here. NPC is a fatal autosomal recessive disorder clinically characterized by hepatosplenomegaly and progressive neurological deterioration. At the cellular level, it causes aberrant cholesterol trafficking and accumulation of unesterified cholesterol in lysosomes. Mutations in NPC1 and NPC2 are cause of disease in respectively, 95% and 5% of NPC patients. The p.Pro120Ser causing mutation in NPC2 observed in the Iranian patients was earlier observed in the only other NPC2 patient reported from the Middle East. The study demonstrates that in addition to greatly facilitating gene discovery, exome sequencing has notable potentials for diagnosis, particularly for diagnosis of atypical cases.

Validation of the Persian version of the 40-item amyotrophic lateral sclerosis assessment questionnaire

BACKGROUND

As a disease of motor nervous system (motor neuron disease), amyotrophic lateral sclerosis (ALS) has a great impact on several aspects of quality of life (QoL). Generic questionnaires of QoL do not address all the especial features of ALS and therefore translation and validation of disease specific questionnaires such as Amyotrophic Lateral Sclerosis Assessment Questionnaire 40-item (ALSAQ-40) is necessary for assessment of patients with different languages. The aim of this study was to review the validation of the Persian version of the ALSAQ-40.

METHODS

Meticulously translated ALSAQ-40 was completed by 21 ALS patients. Internal reliability was evaluated using Cronbach's alpha coefficient and item-total correlation was also used to evaluate the correlation of each question with total score. Validity was evaluated through comparison with Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRS-r) and the 36-Item Short Form Health Survey (SF-36).

RESULTS

Cronbach's alpha coefficient was 0.91-0.96 for different scales of the ALSAQ-40. All the 40 questions of the questionnaire had correlation greater than 0.5. Correlation coefficient of all the related scales of the Persian version of ALSAQ-40, SF-36 and ALSFRS-r was greater than 0.59 with P value < 0.001.

CONCLUSION

Measures of the Cronbach's alpha coefficient and item-total correlation demonstrated reliability and consistency of the questionnaire, and correlation coefficients confirmed the validity of different items in the questionnaire. This study showed that the Persian version of the ALSAQ-40 is a reliable and valid questionnaire for the evaluation of QoL in ALS patients with Persian language.

Genetic analysis and SOD1 mutation screening in Iranian amyotrophic lateral sclerosis patients

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease, and the most common in European populations. Results of genetic analysis and mutation screening of SOD1 in a cohort of 60 Iranian ALS patients are here reported. Initially, linkage analysis in 4 families identified a disease-linked locus that included the known ALS gene, SOD1. Screening of SOD1 identified homozygous p.Asp90Ala causing mutations in all the linked families. Haplotype analysis suggests that the p.Asp90Ala alleles in the Iranian patients might share a common founder with the renowned Scandinavian recessive p.Asp90Ala allele. Subsequent screening in all the patients resulted in identification of 3 other mutations in SOD1, including p.Leu84Phe in the homozygous state. Phenotypic features of the mutation-bearing patients are presented. SOD1 mutations were found in 11.7% of the cohort, 38.5% of the familial ALS probands, and 4.25% of the sporadic ALS cases. SOD1 mutations contribute significantly to ALS among Iranians.

Antinociceptive effect of chronic lithium on visceral hypersensitivity in a rat model of diarrhea-predominant irritable bowel syndrome: The role of nitric oxide pathway

BACKGROUND AND AIM

Lithium, a widely used drug in bipolar-affective disorders, plays gastro-protective roles. The effects of lithium on several tissues are mediated through nitric oxide (NO), which regulates gastrointestinal motility and mucosal integrity. The aim of this study was to investigate the protective effect of chronic lithium administration on visceral hypersensitivity and to investigate the role of NO as a potential mechanism of lithium in a rat model of irritable bowel syndrome.

METHODS

Colitis was induced by the intracolonic administration of acetic acid. After subsidence of inflammation on the seventh experimental day, nociception and defecation parameters were measured. A subgroup of animals had been pretreated with lithium carbonate (600 mg/L) for 35 days. Thereafter, either a non-selective NO synthase (NOS) inhibitor (N-nitro-L-arginine methyl ester [L-NAME], 10 mg/kg), a selective NOS inhibitor (aminoguanidine, 100 mg/kg), or saline were administered intraperitoneally 1 h before measurements.

RESULTS

Chronic lithium attenuated the visceral hypersensitivity, increased the nociceptive threshold, and decreased stool frequency. L-NAME and aminoguanidine decreased the nociceptive threshold and reduced the protective effects of lithium on visceral hypersensitivity. Stool frequency was increased in both the lithium-treated and water-treated groups by L-NAME administration, but not aminoguanidine. The form of defecation in the lithium-treated rats shifted toward hard stools rather than being soft and formless, but NOS inhibitors did not change the stool consistency pattern.

CONCLUSION

The results indicate the antinociceptive property of chronic lithium on visceral hypersensitivity. As this effect was lowered by NOS inhibitors, NO might play a role in the protective effect of lithium to some extent.