Hereditary Spastic Paraplegia Is a Common Phenotypic Finding in ARG1 Deficiency, P5CS Deficiency and HHH Syndrome: Three Inborn Errors of Metabolism Caused by Alteration of an Interconnected Pathway of Glutamate and Urea Cycle Metabolism

Hereditary Spastic Paraplegias (HSP) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by a progressive rigidity and weakness of the lower limbs, caused by pyramidal tract lesions. Today eighty different forms of HSP have been mapped, sixty-four genes have been cloned, and new forms are constantly being described. HSPs represent an intensively studied field, and the functional understanding of the...