Coexistence of dominant and recessive familial amyotrophic lateral sclerosis with the D90A Cu,Zn superoxide dismutase mutation within the same country

The Cu,Zn superoxide dismutase (Cu,Zn SOD) mutations described in amyotrophic lateral sclerosis (ALS) have, for the most part, a dominant influence. However, while a few cases with a heterozygous D90A mutation have been described in different countries, D90A has been recently proven to be recessively inherited with a common founder effect in Scandinavia. We screened French ALS families for Cu,Zn SOD mutations. The presence of the D90A allele was found in two index-cases, and their families were subsequently studied. In the first family the ALS patients were homozygotes for D90A, while in the second, all ALS patients were heterozygotes. In both families the disease was found to initially involve the lower limbs with slower progression than in sporadic cases, and frequent atypical signs such as paresthesia and urgency of micturition. We determined the D90A allele frequency in controls (n = 200) and sporadic ALS patients (n = 408). No D90A allele was found. This is the first report of coexistence of dominant and recessive families with the D90A Cu,Zn SOD mutation within the same country.     

Mutational analysis of the Cu/Zn superoxide dismutase gene in a Catalan ALS population: should all sporadic ALS cases also be screened for SOD1?

BACKGROUND: SOD1 gene mutations are the most common identified cause of ALS, accounting for approximately 20% of familial ALS cases and around 4% of sporadic ALS cases. However, the prevalence of SOD1 varies in different ethnic groups. No previous epidemiological studies have been carried out in Catalonia. OBJECTIVE: To determine the prevalence of SOD1 gene mutations in a Catalan ALS population, and to analyze the genotype-phenotype relationship. MATERIALS AND METHODS: 30 different FALS pedigrees and 94 sporadic ALS patients were screened for SOD1 mutations using direct sequence analysis. RESULTS: Five of the 30 FALS pedigrees (16.6%) carried a SOD1 mutant. The mutations identified in this group were G37R, D76V, S105L, I112M and N139H. Four SOD1 mutants (4.25%) were found in the sporadic ALS group (SALS). The overall frequency (FALS plus SALS) of SOD1 mutations in our series was 6.45%. In the SALS group, D90A was identified in a patient presenting the typical Scandinavian phenotype. A 53-year-old woman with no family history of ALS carried the N139H mutation. Two unrelated sporadic ALS cases carried the A140A SOD1 mutant. CONCLUSIONS: The prevalence of the SOD1 mutation in FALS in Catalonia is similar to levels in other Mediterranean countries, but lower than those in reports studying the Belgian, Japanese, and Scottish populations. The prevalence of the SOD1 mutation was 4.25% in patients with no family history of ALS. These results may have significant repercussions on genetic counseling, and screening for the SOD1 mutation in sporadic ALS cases must therefore be considered.     

Sporadic ALS associated with the D90A Cu,Zn superoxide dismutase mutation in Russia

Twenty blood samples from Russian patients (Moscow) with idiopathic motor neurone disease were analysed for mutations in the Cu,Zn superoxide dismutase (Cu,Zn SOD) gene. Two patients (10%) with the amyotrophic lateral sclerosis (ALS) form of the disease were found to have a disease-related mutation. One patient appears to have autosomal recessive adult-onset ALS associated with homozygosity for D90A and presents the characteristic phenotype of very slowly ascending paresis with both lower and upper motor neurone signs. Another patient, heterozygous for D90A, presents ALS with lumbar onset and rapid progression. This is the first report of a Cu,Zn SOD mutation in ALS in Russia.     

Superoxide dismutase gene mutations in Italian patients with familial and sporadic amyotrophic lateral sclerosis: identification of three novel missense mutations

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting motor neurons. The majority of the patients are sporadic cases (SALS), while 5-10% of the patients have a family history of ALS (familial ALS or FALS). Mutations in the gene coding for cytoplasmic Cu/Zn superoxide dismutase (SOD1) have been identified in about 20% of FALS cases. We found SOD1-gene mutations in five of 34 unrelated FALS, and in two of 44 SALS patients. Three FALS patients carried the previously described A4V (two cases) and L84F mutations (one case), while two FALS patients carried new missense mutations: a G12R substitution in exon 1, and a F45C substitution in exon 2, respectively. The newly identified mutations were both associated with a slowly progressive disease course. Two SALS patients carried the homozygous D90A and the heterozygous I113T mutation, respectively. In addition, in one SALS patient we identified an A95T amino acid substitution, that is apparently a non-pathogenic SOD1 variant. Our study increases the number of ALS-associated SOD1 gene mutations.     

A novel central motor conduction abnormality in D90A-homozygous patients with amyotrophic lateral sclerosis

Patients with amyotrophic lateral sclerosis (ALS) who are homozygous for the D90A SOD1 mutation have been noted to have central motor abnormalities distinct from those of patients with idiopathic ALS. We stimulated the motor cortex of ten patients homozygous for the D90A SOD1 mutation, using transcranial magnetic stimulation (TMS), and recorded the response evoked in the right first dorsal interosseous muscle when the muscle was at rest and when voluntarily active. A subgroup of patients had two distinct evoked responses when the cortex was stimulated at high intensity with the muscle at rest. When the muscle was modestly contracted, the first of these responses disappeared, whereas the second response was facilitated. Both fast and slow components of the corticospinal tract were usually intact and excited by TMS in these patients. We propose that there is an abnormality of intracortical or intraspinal inhibition in a subgroup of D90A SOD1 ALS patients, which suppresses fast-conducted activity when the muscle is active. Apart from further defining the phenotype of familial ALS, these findings may have importance in understanding the pathogenesis of central motor abnormalities in these patients.     

铜/锌超氧化物岐化物1突变致肌萎缩侧索硬化一家系分析并文献复习

目的探索一肌萎缩侧索硬化(ALS)家系基因突变位点并进行文献复习。方法对已知常见的ALS致病基因进行检测,进而对国内铜/锌超氧化物岐化物1(SOD1)基因突变型ALS进行文献复习。结果该家系患者平均起病年龄为(37.8±11.6)岁,均以肢体症状起病,平均病程约1.3年,死于呼吸衰竭。该家系SOD1基因4号外显子第305位存在AG突变(D102G)。目前国内报道的SOD1突变基因有26种。起病年龄最早者20岁,最晚者67岁;病程最短者仅1月,最长者达14年。86.4%的患者以肢体症状起病,4.5%以延髓症状起病,7.7%的患者以肢体和延髓症状起病。SOD1基因可表现为完全外显或不完全外显。结论 D102 G为国内首次报道的ALS疾病相关突变。不同SOD1基因突变位点临床症状具有异质性。     

Heterozygous SOD1 D90A mutation presenting as slowly progressive predominant upper motor neuron amyotrophic lateral sclerosis

Of all the SOD1 gene mutations described, uniquely the D90A mutation has been identified in recessive, dominant, and apparently sporadic cases. We describe a patient with a sporadic form of amyotrophic lateral sclerosis (ALS) in which a heterozygous A > C exchange at position 272 in the SOD1 gene was detected. This mutation results in an amino acid substitution of alanine for aspartate at position 90 (D90A). The patient had a 12-year history of disease characterized by slow progression. Clinical examination at last follow-up revealed predominant upper motor neuron (p-UMN) involvement, with atrophies only in distal muscle of upper limbs. Electrophysiological examination revealed lower and upper motor neuron involvement. Family history was negative for neurological disease. This report shows that D90A in heterozygous state may cause p-UMN phenotype with very slow progression.     

Superoxide dismutase in amyotrophic lateral sclerosis patients homozygous for the D90A mutation

The most common of the amyotrophic lateral sclerosis (ALS)-associated superoxide dismutase-1 (SOD1) mutations, D90A, differs from others in its high structural stability and by the existence of both recessive and dominant inheritance. Here SOD1 in CNS and peripheral organs from five ALS patients homozygous for D90A were compared to controls. In most areas, including ventral horns, there were no significant differences in SOD1 activities and Western blotting patterns between controls and D90A cases. The SOD1 activities in areas vulnerable to mutant SOD1s, ventral horns and precentral gyrus were intermediate among CNS areas and much lower than in kidney and liver. Thus, the vulnerability of motor areas is not explained by high SOD1 content. The findings argue against the idea of expression-reducing protective factors being present near the D90A locus in recessive pedigrees. The similarity to wild-type SOD1 prompts speculations on the involvement of the latter in sporadic ALS.     

Clinical characteristics of SOD1 gene mutations in UK families with ALS.

Five to ten percent of patients with ALS have a family history of the disease, inheritance is usually autosomal dominant. Mutations of the SOD1 gene were first identified in a proportion of families with ALS by Rosen et al. The SOD1 gene encodes the enzyme copper zinc superoxide dismutase. Patients were studied from throughout the UK, where more than one individual in the family had ALS. Clinical history and examination of the individual and family were obtained, and DNA extracted from leukocytes of whole blood samples. Mutations were identified by standard sequencing methods. To date, 12 different mutations of SOD1 have been identified in 17 different families, representing around 20% of all ALS families studied. The mutations were mainly single base substitutions - H48Q, G72S, G93R, G93V, E100G, D101N, D101G, G108V, I113T, D125H, I149T - and also an insertion mutation - 132insTT - leading to a premature stop codon. The mutations were present in exons 2-5. We did not identify mutations in exon 1, although these have been identified by others in different patient samples. We have identified SOD1 mutations in around 20% of UK families with ALS studied. This is similar to that reported in other populations. Mutations have now been identified in all exons of SOD1. The individual mutations do not precisely predict disease severity, and generally it is difficult to give a specific prognosis based on the individuals' SOD1 mutations. We continue to investigate the possible pathogenic mechanisms of the SOD1 mutations. We have studied the neuropathology in patients with SOD1 mutations. We are also performing linkage studies to identify the genes involved in the 80% of families where an SOD1 mutation has not been identified.     

The epidemiology of CuZn-SOD mutations in Germany: a study of 217 families

We screened 217 patients from Germany (n = 213), Austria (n = 2) and Switzerland (n = 2) with a positive family history for amyotrophic lateral sclerosis (ALS) for mutations in the copper/zinc superoxide dismutase (SOD1) gene. We found that 13% of the families tested carried mutations. By analyzing inheritance, we detected a clear-cut co-segregation in 5 of the 28 families; however, in two families with an established mutation, co-segregation was absent. In Germany, the R115G mutation is comparatively frequent and exhibits a specific aggressive phenotype. The L144F mutation, which is the most prevalent mutation in the Balkan countries, and the D90A mutation which is the most frequent SOD1 mutation globally, seem to be the second most common disease-causing mutations in Germany.     

A novel SOD1 mutation in a young amyotrophic lateral sclerosis patient with a very slowly progressive clinical course

Approximately 10% of amyotrophic lateral sclerosis (ALS) cases are familial, and the Cu/Zn superoxide dismutase (SOD1) gene mutation accounts for 20% of them. More than 100 SOD1 mutations have been described, some with peculiar phenotypes. Moreover, mutations in the SOD1 gene have been described in apparently sporadic ALS cases. We report a new mutation (D11Y) in the Cu/Zn superoxide dismutase gene in a patient with ALS and an unusually slow disease progression. Muscle Nerve, 2010     

A novel SOD1 gene mutation in a Korean family with amyotrophic lateral sclerosis

BACKGROUND: Superoxide dismutase 1 (SOD1) gene mutations are responsible for approximately 20% of all familial amyotrophic lateral sclerosis (ALS) cases. However, these cases, especially those with SOD1 gene mutations, have not been reported in Korea. OBJECTIVES: The SOD1 gene in Korean family with ALS was screened for potential mutations and the clinical data was collected. MATERIALS AND METHODS: The clinical histories and neurological findings of the family members were obtained. Genomic DNA was isolated from the leukocytes of whole blood samples and the coding region of the SOD1 gene was analyzed by PCR and sequencing. RESULTS: The family with ALS showed a novel missense mutation in the SOD1 gene, which was heterozygous for the mutation, GGC to GTT, causing the substitution of valine for glycine at codon 10 (Gly10Val) in exon 1. Clinically, the patients exhibited early onset and rapid disease progression. CONCLUSIONS: Familial ALS with a novel Gly10Val mutation in the SOD1 gene showed severe clinical features. The mutation lies in a region involved in a dimer contact in the three-dimensional structure of the SOD1 protein. This study expands the number of ALS-associated SOD1 gene mutations.     

ALS with variable phenotypes in a six-generation family caused by leu144phe mutation in the SOD1 gene.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive neurological disorder. The mutations of Cu/Zn superoxide dismutase gene (SOD1) are responsible for familial ALS. We investigated a large family of Istro-Rumanian origin characterized by an autosomal dominant ALS occurring in 18 cases (three of which are still alive) throughout six generations. METHODS: Clinical data were available for nine patients from the 2nd generation onward, among which one contained the neuropathological details. The mean age at onset of the disease (+/-SD) was 57.3+/-8.9 years (range 49-72), while the duration of the disease spanned over a length of time equal to 4.9+/-1.96 years (range 1.5-7). The analysis of the coding region of SOD1 was done by PCR and direct sequencing. The SOD1 activity was measured by using the red and mononuclear cells belonging to three of the patients. RESULTS: The leu144phe mutation of SOD1 was identified in four patients while a normal sequence was found in five healthy related subjects. The molecular defect was responsible for a decrease in SOD1 activity. Most of patients in this family presented clinical manifestations of ALS (in particular, the lower limb onset variant) not as severe as typical ALS caused by other SOD1 mutations. However, one patient suffering from hyperthyroidism for 17 years, showed an early onset and a rapidly progressing ALS coupled with dementia. CONCLUSIONS: We described a large family with a relatively not severe phenotype of ALS (due to a leu144phe SOD1 mutation) that was compromised in one patient by a concomitant hyperthyroidism.     

Molecular analysis of the superoxide dismutase 1 gene in Spanish patients with sporadic or familial amyotrophic lateral sclerosis

We performed a genetic analysis of the Cu/Zn superoxide dismutase gene (SOD1) in Spanish patients with sporadic or familial amyotrophic lateral sclerosis (ALS). We found mutations in 2 of 11 families (18%) with ALS. In addition, 1 of the 87 sporadic ALS patients studied harbored a mutation in the same gene. We identified G37R in exon 2 of the SOD1 gene in 1 family. Another patient, with sporadic ALS, showed a novel N65S in exon 3. In addition, we found a novel I112M in exon 4 in another family. Our data highlight the genetic heterogeneity of patients with ALS harboring mutations in the SOD1 gene and confirm that families with autosomal dominant inheritance of the trait, regardless of their ethnic background, are more likely to carry mutations in such a gene.     

Novel SOD1 N86K mutation is associated with a severe phenotype in familial ALS

Familial amyotrophic lateral sclerosis (ALS) is frequently associated with mutations in the SOD1 gene. We identified a rapidly progressive disease in a patient with an inherited ALS. The identified heterozygous T>A exchange in position 1067 in the SOD1 gene results in an amino acid substitution of lysine for asparagine at position 86 (N86K) of the SOD1 protein. The family history suggested that this autosomal dominantly inherited mutation may be associated with rapidly progressive disease.     

A novel mutation Asp90Val in the SOD1 gene associated with Japanese familial ALS

We have identified a novel mutation in exon 4 of the Cu/Zn superoxide dismutase (superoxide dismutase 1: SOD1) gene (GAC to GTC), which resulted in an Asp⁹⁰ to Val substitution in a Japanese family with amyotrophic lateral sclerosis (ALS) inherited as an autosomal dominant trait. The patients in this family usually died in 2–3 years without sensory or urinary impairment. The SOD1 activity was lower in the proband as compared to the normal controls. The clinical characteristics of this family resemble those of some patients heterozygous for the Asp90Ala mutation, but both the clinical features and SOD1 activity of this family differ from those of patients homozygous for the ASP90Ala mutation.     

Phenotypic Heterogeneity in a <Emphasis Type="BoldItalic">SOD1</Emphasis> G93D Italian ALS Family: An Example of Human Model to Study a Complex Disease

We report different clinical expression in seven members of a large family with amyotrophic lateral sclerosis (ALS) and the G93D mutation in exon 4 of the Cu/Zn superoxide dismutase (SOD1) gene. The ALS clinical course in the proband showed an unusually fast progression of the disease compared to the paucisymptomatic presentation associated to this mutation in the two previously Italian families described. The remaining mutation carriers did not show the aggressive clinical course displayed by the proband. We selected few genes known to be ALS modifiers searching for genetic variants that could explain the wide phenotypic diversity within the family. Exclusion of causative genes such as TDP43, FUS, PGRN and VAPB was performed too. We believe that this kind of family with contrasting phenotypes of ALS may be considered an excellent human model to study the relationship between a wider genetic profile, including modifier genes, and the clinical expression of the disease. Therefore, the novelty of our approach is also represented by the study of a single family to reproduce a composite structure in which search for possible modifier genes/genetic variants linked to SOD1 mutated.     

Motor system abnormalities in heterozygous relatives of a D90A homozygous CuZn-SOD ALS patient of finnish extraction.

Presently, 64 mutations in the gene encoding the enzyme CuZn-superoxide dismutase have been found in a small fraction of amyotrophic lateral sclerosis patients worldwide. All but one of these mutations show autosomal dominant inheritance. In Scandinavia, the D90A mutation is inherited as an autosomal recessive trait and patients have an easily recognizable characteristic phenotype with little variation among patients, even amongst different families. Importantly, all D90A heterozygous relatives of Scandinavian D90A homozygous patients have been reported as clinically unaffected. We have investigated a Canadian family of Finnish extraction in which the D90A homozygous proband developed ALS with the characteristic phenotype. Remarkably, two D90A heterozygous relatives show slight symptoms and signs of motor system involvement, suggesting that the final phenotype of an individual with a CuZn-superoxide dismutase mutation is shaped by the combination of the particular CuZn-SOD mutation, other polymorphic modifying genes elsewhere in the genome, stochastics and possible environmental factors.     

CuZn-superoxide dismutase in D90A heterozygotes from recessive and dominant ALS pedigrees

Mutations in CuZn-superoxide dismutase (CuZn-SOD) have been linked to ALS. In most cases ALS is inherited as a dominant trait and there is marked reduction in CuZn-SOD activity in samples from the patients. The D90A mutation, however, mostly causes ALS as a recessive trait and shows near normal CuZn-SOD activity. A few familial and sporadic ALS cases heterozygous for the D90A mutation have also been found. Haplotype analysis of both types of D90A families has suggested that all recessive cases share a common founder and may carry a protective factor located close to the D90A mutant CuZn-SOD locus. To search for effects of a putative protective factor we analysed erythrocytes from D90A heterozygous individuals for SOD activity by a direct assay, subunit composition by immunoblotting, and zymogram pattern formed by isoelectric focusing and SOD staining. Included were heterozygotes from 17 recessive families, and from 2 dominant families and 4 apparently sporadic cases. The CuZn-SOD activity in the recessive and dominant groups was found to be equal, and 95% of controls. The ratio between mutant and wildtype subunits was likewise equal and 0.8:1 in both groups. The zymograms revealed multiple bands representing homo- and heterodimers. There were, however, no differences between the groups in patterns or in ratios between the molecular forms. In conclusion we find no evidence from analyses in erythrocytes that the putative protective factor in recessive families acts by simply downregulating the synthesis or altering the molecular structure or turnover of the mutant enzyme.