Phenotypic and Genotypic Studies in Congenital and Early Onset Ataxias

All patients will be examined by a geneticist or a neuropediatric. All clinical data will be collected.

Strategy of the molecular study :

• for all multiplex and consanguineous families a linkage analysis (loci ATCAY and ABC7 and others AC known genes) will be performed.
• For all sporadic patients as well as linked multiplex and consanguineous families : sequencing of all coding exons of the gene ATCAY and others AC known genes.
• For all sporadic male patients and linked families : sequencing of all coding exons of the gene ABC7.
• For all patients with suggestive features : sequencing of all coding exons of the gene GPR56, VLDLR, NHE6 or other candidate gene.
• In consanguineous families : linkage analysis using SNP-array and analysis of candidate genes present in the regions of extended homozygosity
• linkage analysis in dominant families and analysis of candidate genes in the linked regions.
• If a new AC locus is identified (using linkage or CGH array), this gene will be sequenced in all patients.

Inclusion criteria

• Patient, child or adult, affected with a congenital or early-onset ataxia defined by:
• Neurological symptoms observed before age of 2 years.
• Non progressive cerebellar ataxia observed at the time of examination. Karyotype done or in progress

Exclusion criteria

• Metabolic disease
• Specific MRI malformations suggesting a peculiar entity : molar tooth (joubert syndrome), superior vermis dysplasia with cleft (Oligophrenin)
• Muscle weakness and elevated creatine phosphokinase (CPK)
• Clearly progressive ataxia.
• Absence of signature of the informed consent.
• Absence of affiliation to social security