The field of hereditary diseases has expanded significantly since the elucidation of the genetic basis of phenylketonuria, which marked a turning point in the understanding of inborn errors of metabolism. In Spain, this progress has been driven by the pioneering work of Magdalena Ugarte and Federico Mayor Zaragoza, who initiated and developed a structured approach to the molecular diagnosis, clinical management, and research of these disorders, beginning in the province of Granada and later extending to a national level. Under her leadership, the Centro de Diagnóstico de Enfermedades Moleculares (CEDEM) became a reference center for the comprehensive evaluation of inherited metabolic and genetic disorders, integrating biochemical screening, advanced molecular diagnostics, and genetic counseling. CEDEM also fosters research on pathophysiology and novel therapeutic strategies, contributing to the early detection, prevention, and treatment of these conditions.