Does a normal frataxin test result rule out the possibility of friedreich ataxia.and does a normal result of a cat scan rule out cerebellar ataxia ?

No and no: There are several forms of cerebellar ataxia. There are markers that have been found, but most cases are not diagnosed by the marker gene but by appropriate clinical evaluation. Early in the course ct and MRI may be normal.

No and No: The 'frataxin test' reveals the presence of repeat expansions in the frataxin gene which is detected in 96% of fa patients. The rest are due to point mutations uncovered by sequence analysis of the gene and is a separate test. Mri is better than ct to study the posterior fossa. Results depend on the type of cerebellar ataxia of which fa is only one.