[Superoxyde dismutase 1 gene abnormalities in familial amyotrophic lateral sclerosis: phenotype/genotype correlations. The French experience and review of the literature]. / Les anomalies du gène superoxyde dismutase 1 dans la sclérose latérale amyotrophique familiale: corrélations phénotype/génotype et implications pratiques. L'expérience française et revue de la littérature.

About 20 p. cent of cases of amyotrophic lateral sclerosis are familial (FALS). Fifteen percent of FALS cases are associated with an abnormality in the superoxide dismutase 1 (SOD1) gene. To date, more than 100 different genetic abnormalities have been reported, all except two are autosomal dominant. The clinical characteristics of patients presenting with FALS associated with an SOD1 abnormality is homogeneous when there is no doubt about the hereditary aspect of the genetic abnormality: mean age at onset 42 years, limb onset, slow evolution. Except when present in the setting of a clearly inherited disease (FALS) (several patients through several generations), the causality of a given SOD1 mutation often remains an open question. Consequently, search for SOD1 mutation is not warranted when atypical features such as young age at onset or slow progression are present. Conversely, a complete family study is justified to determine the precise role of a given SOD1 mutation because of the large number of potential SOD1 mutations, the variability of the transmission mode, and the non-exceptional absence of proven causality for ALS. Specific cases where a frequent SOD1 mutation with a recognized causal effect is recognized (no more than 15 out of more than 90 mutations) would be an exception.

SMN1 gene study in three families in which ALS and spinal muscular atrophy co-exist.

Spinal muscular atrophy (SMA) is caused by SMN1 gene deletions or mutations, and ALS is the most frequent motor neuron condition in adults. The authors describe three families in which ALS and SMA coexist. The authors found that no SOD1 mutation was found within these families; all three ALS cases had at least two SMN1 copies; and an abnormal SMN1 gene locus did not explain the co-occurrence of these two motor neuron disorders in these families.

Compound heterozygous D90A and D96N SOD1 mutations in a recessive amyotrophic lateral sclerosis family.

We describe a French amyotrophic lateral sclerosis (ALS) family with two distinct mutations in the Cu/Zn superoxide dismutase (SOD1) gene. The D90A mutation has been well described and clearly shown to cause recessive ALS. In this family, affected individuals are heterozygous for the D90A mutation and also carry a single copy of a novel SOD1 mutation, D96N. We propose that in this family both mutations are required for the development of disease.

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.

[Opsoclonus-myoclonus syndrome in the adult. 4 cases]. / Syndrome opsoclonus-myoclonies de l'adulte. Quatre observations.

Four cases of opsoclonus in adults are reported. In all cases, it was associated with myoclonus and cerebellar syndrome. In 2 cases, the clinical and biological picture was suggestive of an infectious origin, and the patients recovered. The last cases are paraneoplastic opsoclonus revelating a pulmonary carcinoma and a breast cancer. The two patients died from metastasis after a transient improvement of ocular disorder. The pathophysiology of opsoclonus is discussed.

Genetics of familial ALS and consequences for diagnosis. French ALS Research Group.

Familial amyotrophic lateral sclerosis (fALS) is a well-recognised condition that accounts for almost 10% of all cases of ALS. Most cases are now known to be transmitted by an autosomal dominant trait. When fALS is compared clinically to sporadic ALS, 20% of cases manifest atypical features such as pain, paraesthesia or urgency micturition. Moreover, a disease duration of over 10 years, with very slow progression, appears to occur almost exclusively in cases of fALS. Studies of superoxide dismutase (SOD1) mutations in fALS have shown that the disease may be multidegenerative, with oculomotor or cerebellar involvement. Molecular genetics has also demonstrated that not all SOD1 mutations have a dominant influence, and the detailed description of the Scandinavian D90A homozygous mutation is very informative in this regard. Misdiagnosis of fALS can be attributed to one of the following situations: (i) atypical phenotype ALS with a multidegenerative profile; (ii) unusually long lasting ALS with mild motor neuron involvement; (iii) significant clinical heterogeneity between affected family members; (iv) low reliability of family history; (v) existence of an unknown or unexpected mode of transmission; and (vi) other multidegenerative disorders with motor neuron involvement. Pedigrees and fALS cases corresponding to these situations are presented.

Identification of six novel SOD1 gene mutations in familial amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the premature death of motor neurons. In approximately 10% of the cases the disease is inherited as autosomal dominant trait (FALS). It has been found that mutations in the Cu/Zn superoxide dismutase gene (SOD1) are responsible for approximately 15% of FALS kindreds. We screened affected individuals from 70 unrelated FALS kindreds and identified 10 mutations, 6 of which are novel. Surprisingly, we have found a mutation in exon 3, which includes most of the active site loop and Zn2+ binding sites, a region where no previous SOD1 mutations have been found. Our data increase the number of different SOD1 mutations causing FALS to 55, a significant fraction of the 154 amino acids of this relatively small protein.