X-linked Ataxia

Fragile X tremor ataxia syndrome

Fragile X tremor ataxia syndrome (FXTAS) is believed to be a common cause of ataxia in males. This condition shows X-linked inheritance, which means that males show symptoms much more often than females. The disease is caused by a repeat expansion. There are several diseases associated with repeat expansions in the fragile X gene including FXTAS, fragile X mental retardation syndrome, and premature ovarian failure in females. The repeat numbers that are usually associated with FXTAS are in the 55-200 range. Individuals with FXTAS are NOT mentally retarded, but family members may be at risk for having a child with fragile X mental retardation.

SCAX syndromes

Several types of ataxia are believed to be caused by genes on the X-chromosome. These ataxias are called “X-linked” and they tend to affect males more often and more severely than females. These types of ataxia are named in a similar pattern to SCA ataxias (SpinoCerebellar Ataxia X-linked). The ataxias are numbered in the order of their discovery. At the present time, SCAX1-SCAX5 have been reported, but no genes have been identified for any of these conditions.