- Spectrin mutations cause spinocerebellar ataxia type 5. Ikeda, Y., Dick, K.A., Weatherspoon, M.R., Gincel, D., Armbrust, K.R., Dalton, J.C., Stevanin, G., Dürr, A., Zühlke, C., Bürk, K., Clark, H.B., Brice, A., Rothstein, J.D., Schut, L.J., Day, J.W., Ranum, L.P. Nat. Genet. (2006)