PGK1 and Parkinsonism: For example, in one case report, a child with PGK1 deficiency developed parkinsonism at 9 years of age, whereas the mother, a heterozygous carrier of the mutation, developed parkinsonism at 36 years of age, suggesting a gene dose-dependent effect of PGK1 deficiency in conferring susceptibility to PD (Sakaue et al., 2017).