Ataxia is a neurodegenerative disease that results in loss of posture, balance and coordination of movement. An emerging picture is that impairment of a type of star-shaped brain cell called astrocytes, is associated with a lack of functional support of neurons that subsequently result in such motor impairments. In the photograph, a human astrocyte (red) bearing the mutant gene
causing the disease spinocerebellar ataxia type 7 (SCA7) displays aggregates of the ataxin-7 protein (green) within its cell nucleus (blue). Such protein aggregates are characteristic of progressive disease. In healthy cells, this protein is more evenly distributed throughout the nucleus where it functions in controlling the activity of a number of genes.