CA8 and cerebellar ataxia: MRI showed pontocerebellar hypoplasia in three recessively inherited progressive ataxias, namely cerebellar ataxia mental retardation with/out quadrupedal locomotion type 1 (CAMRQ1, OMIM 224050), type 2 (CAMRQ2, OMIM 610185) and type 3 (CAMRQ3, OMIM 613227).