Clinical and biochemical footprints of inherited disorders of heme synthesis and porphyrias: Insights from the IEMbase and dyadic nomenclature.

Inherited disorders of heme synthesis and the porphyrias comprise a clinically diverse group of inborn errors and acquired metabolic phenotypes caused by disruption of a shared biochemical pathway. This study summarizes the clinical and biochemical footprints of disorders represented in IEMbase and aligned with dyadic disease nomenclature. Twelve disorders caused by defects in ten genes were reviewed, including enzymatic defects of the canonical heme biosynthetic pathway and related erythroid regulatory or transport disorders. The resulting phenotypes span acute neurovisceral attacks, painful or blistering photosensitivity, hemolytic and sideroblastic anemia, liver dysfunction, renal complications, neuropsychiatric manifestations, and characteristic urinary, plasma, erythrocyte, and fecal metabolite abnormalities. Across the porphyrias, diagnosis depends primarily on recognition of pathway-specific biochemical signatures, including ALA and PBG accumulation in acute hepatic porphyrias, type I porphyrin excess in congenital erythropoietic porphyria, uroporphyrin and heptacarboxyl porphyrin accumulation in porphyria cutanea tarda, and erythrocyte protoporphyrin excess in protoporphyrias. Molecular testing confirms the underlying genotype, supports family studies, and enables dyadic disease naming, but should be interpreted together with biochemical evidence and clinical context. This structured integration of symptoms, metabolites, genes, inheritance, and treatment provides a practical framework for recognizing these rare but treatable disorders and highlights the value of IEMbase as a knowledge resource for inherited metabolic disease.