這個基因編碼羥甲基雙烷合酶超家族的一個成員。編碼的蛋白質是血紅素生物合成途徑的第三種酶，催化四種恐孔素原分子的從頭到尾縮合成線性羥甲基雙烷。該基因突變與常染色體顯性遺傳病急性間歇性卟啉癥有關。另外，還描述了編碼不同亞型的剪接轉錄變體。[由RefSeq提供，2008年7月]
This gene encodes a member of the hydroxymethylbilane synthase superfamily. The encoded protein is the third enzyme of the heme biosynthetic pathway and catalyzes the head to tail condensation of four porphobilinogen molecules into the linear hydroxymethylbilane. Mutations in this gene are associated with the autosomal dominant disease acute intermittent porphyria. Alternatively spliced transcript variants encoding different isoforms have been described. [provided by RefSeq, Jul 2008]