| An extremely rare and complex form of hereditary spastic paraplegia reported in only 4 patients from 2 families to date. The disease has characteristics of spastic paraplegia (presenting between the ages of 1 to 4 years with abnormal gait) associated with microcephaly, amyotrophy, cerebellar signs (e.g. dysarthria) aggressiveness, delayed puberty and mild to moderate intellectual disability. SPG64 is due to mutations in the ENTPD1 gene (10q24.1), encoding ectonucleoside triphosphate diphosphohydrolase 1. |