[Spinocerebellar ataxia type VII (AEC 7). Report of a Spanish family with the disease].

INTRODUCTION

The dominant autosomic ataxias are a group of neurodegenerative disorders caused by expansion of a CAG triplet in different genes, found along the genome. The dominant autosomic ataxias present very varied clinical findings. However, genetic studies are being done to establish the genotype-phenotype relationship of the different autosomal dominant ataxias.

CLINICAL CASE

A 50 year old man had alterations in gait, dysarthria and visual changes (retinal degeneration). Study of the different genes known to be responsible for the dominant autosomic ataxias have an expansion of the superior CAG of more than 37 repetitions of the gene SCA 7, whilst in the normal control population there are 9-18 repetitions of this gene. Other members of the family had similar clinical findings, although the age of onset varied. One did not have retinal degeneration but did have expansion of the SCA 7 gene.

CONCLUSIONS

The non-pathological range of SCA 7 in the Spanish population, according to our study, is between 9-18 repetitions of triplet CAG, whilst in members of the patient's family they were over 37. The clinical findings, which were similar in all patients were found in all patients except for one, who did not have retinal degeneration. We observed the phenomenon of genetic anticipation in the family studied.