A renal tubular transport disease characterized by impaired renal tube reabsorption of proline, hydroxyproline and glycine and elevated urine levels of the imino acids and glycine that has_material_basis_in homozygous mutation in SLC36A2 on chromosome 5q33.1 combined with either heterozygous mutation in SLC6A20 gene on chromosome 3p21.31 or homozygous mutation in SLC6A19 on chromosome 5p15.33.