Aprataxin (APTX) is a hydrolase that has been shown to catalyze the hydrolysis of 5′–5′ adenylylated DNA and RNA12,23,24 and APTX mutations cause the neurodegenerative disease Ataxia with Oculomotor Apraxia 1 (AOA1)5,12,27,28. The gene discussed is APTX; the disease is cerebellar ataxia.