Porphobilinogen is a colorless compound that plays a crucial role in the biosynthesis of hemoglobin, the protein in red blood cells responsible for transporting oxygen. It is formed from the condensation of two molecules of aminolevulinic acid and is an important intermediate in the production of porphyrins, which are essential for various biological functions. In the body, porphobilinogen is further processed through a series of enzymatic reactions to eventually produce heme, the iron-containing component of hemoglobin. Abnormalities in the production or metabolism of porphobilinogen can lead to various disorders, collectively known as porphyrias, which can affect the skin and nervous system.