transcription factors, and this effect is believed to play a significant role in ataxin 1 toxicity. Another protein shown to have significant interactions with ataxin 1 is the leucine-rich acidic nuclear protein or LANP. Its function is unknown, but it is predominately expressed in the same neurons as ataxin 1 and has been shown to localize in the nuclei of these neurons at the same substructures as ataxin 1. LANP only interacts with the polyglutamine region of ataxin 1, and its interactions are stronger as the number of glutamine residues increases, so the two proteins are likely vital to each other's functions in neurons and LANP may also facilitate pathology of mutant ataxin 1 proteins. Ataxin 1 like, also called Brother of Ataxin 1 or Boat, has significant interactions with ataxin-1 and many associated proteins, like N-CoR. Ataxin 1 like has reduced expression in transgenic mice models and has been shown to moderate cytotoxicity of ataxin-1. Toxicity from the mutated protein causes degradation in neural tissues. This includes loss of dendritic aborization, or branching, early in disease progression and eventual atrophy of brain tissues in later stages. SCA1 causes moderate degradation of a variety of tissues, including both hemispheres of the cerebellum, the cerebellar vermis, the pons, and the brain stem. It also causes mild atrophy in cerebral cortical tissue. A recent study also found significant atrophy of the spinal cord and flattening of the posterior column and found a correlation between cord area, CAG repeats, and SARA scores in SCA1. Central nervous system tissues, unlike that of bone, muscle, or skin, lacks mechanisms for endogenously generating and differentiating new cells and for restoring long distance patterns and connections as they are lost, so as degeneration progresses the losses are permanent. Diagnosis and evaluation Most SCAs and other ataxic disorders are clinically heterogeneous, meaning clinical signs and symptoms are similar between diseases and distinguishing between diseases with a neurologic exam alone is difficult. In symptomatic persons, diagnosis of ataxia related disorders often requires a neurological exam, evaluation of neurological and family history, and molecular genetic testing. Absence of a family history does not exclude hereditary causes like spinocerebellar ataxia type 1 because family history may not have been collected or may be unavailable for certain individuals and new cases may originate from anticipation in an allele with a mutable number of repeats. To establish a diagnosis, molecular genetic testing is