No abstract

No abstract

Clinical revaluation and genetic analysis of six Indian pedigrees, segregating autosomal dominant cerebellar ataxia, slow saccades and peripheral neuropathy, has been undertaken, and expansion at the spinocerebellar ataxia 2 (SCA2) locus was confirmed in 14 affected family members. These families became available from 31 phenotypically similar families seen over the years. In common with other neurodegenerative disorders resulting from expansion of a CAG trinucleotide repeat motif, an inverse correlation between repeat size and age at onset and severity is observed, although the size range (36-45 repeat units) for the expanded alleles is comparatively limited. Saccadic velocity was reduced in all our patients, even in the early stages of the disease. The observation of slow saccades in affected individuals has been proposed previously as an important diagnostic criterion serving to distinguish the SCA2 phenotype. This is now confirmed in a retrospective study of the clinical literature, facilitated by the cloning of the SCA2 gene and the subsequent genetic analysis of families segregating this phenotype. We therefore argue that the clinical appraisal of 'ophthalmoplegia' be subject to more precise definition, as differentiation between the various types of ocular dysfunction can be an important adjunct to diagnosis.

Episodic ataxia type 2 (EA2) is caused by calcium channel (CACNA1A) mutations and typically begins before age 20 years. The molecular basis of late-onset EA2 is unclear. The authors describe a case of late-onset EA2 associated with the first multiple-base pair insertion in CACNA1A. Molecular expression revealed evidence of impaired calcium channel function, suggesting that genetically induced reduction in calcium channel function may associate with cases of late-onset EA2.

No abstract

No abstract

We studied a patient with amyotrophic lateral sclerosis, multifocal motor conduction block, and IgM anti-GM1 antibodies. A sural nerve biopsy demonstrated deposits of IgM at nodes of Ranvier by direct immunofluorescence. The deposits were granular and located in the nodal gap between adjacent myelin internodes, and in some instances, they extended along the surface of the paranodal myelin sheath. When injected into rat sciatic nerve, the serum IgM bound to the nodes of Ranvier, and the binding activity was removed by preincubation with GM1. These observations suggest that anti-GM1 antibodies may have caused motor dysfunction by binding to the nodal and paranodal regions of peripheral nerve.

SummaryVitamin B,,, thiocyanate, and folate levels in the blood were estimated in 69 apparently normal subjects, of whom 26 were non-vegetarian non-smokers, 19 nonvegetarian smokers, 15 vegetarian non-smokers, and nine vegetarian smokers. The serum total (cyanideextracted) B1, level (value A) ranged from 105 to 728 pg/ml, with a mean of 292 pg/ml. The highest values were found in non-vegetarian non-smokers and the lowest in vegetarian smokers. There was no significant difference in value A between smokers as a group and non-smokers as a group. On the other hand, in vegetarians value A was very significantly lower than in non-vegetarians regardless of their smoking habits.It is suggested that A may represent both the proteinbound and free forms of vitamin B1, in the blood, and B mainly the free B12, which may be the physiologically active form. The plasma thiocyanate level varied from 1-0 to 15 Imol/100 ml, being, as expected, much higher in smokers (mean 8 20 ILmol/100 ml) than in non-smokers (mean 2-02 ,umol/100 ml). There was a rough correlation between falling B12 levels and rising thiocyanate levels. The serum folate level ranged from 2-75 to 15 75 ng/ml, and was slightly but significantly higher in vegetarians (mean 6 60 ng/ml) than in non-vegetarians (mean 4 79 ng/mi), reflecting the greater content of folate in a vegetarian diet.