[Spinocerebellar ataxia type 7: clinical and molecular genetic analysis of a Mexican family].

INTRODUCTION

Spinocerebellar ataxias (SCA) constitute a group of neurodegenerative diseases characterized by cerebellar disfunction alone or associated with other neurological anomalies. The combination of progressive cerebellar ataxia, macular pigment dystrophy, ophtalmoplegia, spasticity and an autosomal dominant pattern of transmission is characteristic of SCA 7. Genome wide linkage analysis mapped the defective gene to 3p12 13.

OBJECTIVE

To describe a Mexican family with SCA 7.

CASE REPORTS: We present a family pedigree of 13 individuals with ataxia and other neurologic findings in 3 generations. The evaluation consisted of a complete clinical and neurologic examination; neuropsychologic, neurophysiologic, ophthalmologic, neuroradiologic assessments and a molecular genetic study. The first 2 generations had a history of gait disturbance and visual loss. We objectively found a global cerebellar syndrome, pyramidal signs, visual impairment and ophtalmoparesis in variable grades in all members of the third generation All had progressive retinal degeneration, cerebellar, brainstem and hemispheric atrophy. We observed anticipation phenomena. Genetic analysis of the father of the third generation showed expansion of CAG triplet repeats at the SCA 7 gene.

CONCLUSION

The clinical and genetic findings confirmed the diagnosis of SCA 7, and this is the first report in a Mexican family.