Linkage to chromosome 13q11-12 of an autosomal recessive cerebellar ataxiain a Tunisian family

Objective: To report the clinical findings and the genetic linkage mapping of an autosomal recessive cerebellar ataxia associated to peripheral neurop athy, showing an early onset cerebellar ataxia with retained tendon reflexe s (EOCA) phenotype. Background: EOCA is a clinical syndrome delimited by Ha rding distinguished from Friedreich's ataxia (FA) mainly by the preservatio n of tendon reflexes. Molecular genetic study of patients with EOCA has dem onstrated genetic heterogeneity. A form of autosomal recessive spastic atax ia has been described in Charlevoix Saguenay area in Quebec (ARSACS); the g ene responsible has been mapped to chromosome 13q. Methods: Genetic linkage analysis was performed on 18 members of a large family including 8 of 9 me mbers with EOCA. After exclusion of FA and ataxia with vitamin E deficiency loci as well as loci of autosomal dominant cerebellar ataxias, we performe d a linkage analysis to markers of 13q11-12 region. Results: The 9 affected members of this family showed stereotyped clinical features with cerebella r ataxia, pyramidal syndrome, and a variable degree of axonal peripheral ne uropathy. Linkage was detected between the disease locus and the microsatel lite marker D13S232. Surrounding markers to D13S232 confirmed the linkage a nd showed the homozygosity of the affected members. Conclusion: The family reported here showed the same locus as autosomal recessive spastic ataxia C harlevoix Saguenay disease.