Genetics and Clinical Features of Inherited Ataxias

Ataxia is defined as a pathological loss of motor coordination and can be presented as either the major feature of a neurological disease or one of the clinical signs of a multisystemic disorder. Although ataxia in most disorders results from variable degeneration of neurons in the cerebellum and their afferent/efferent connections, profound proprioceptive sensory loss also causes ataxia (sensory ataxia) with or without involvement of cerebellar neurons. Cerebellar disorders can be divided into sporadic and inherited diseases. The inherited cerebellar ataxias include autosomal recessive, autosomal dominant, X-linked, and mitochondrial cerebellar ataxias. Ataxias that present as intermittent episodes of ataxia are labeled episodic ataxias. In most of these disorders, ataxia is caused by dysfunction and degeneration of the cerebellar cortex and its afferent or efferent fiber connections.