 Inhibition of ALAD by lead leads to anemia primarily because it both inhibits heme synthesis and shortens the lifespan of circulating red blood cells, but also by stimulating the excessive production of the hormone erythropoietin, leading to inadequate maturation of red cells from their progenitors.A defect in the ALAD structural gene can cause increased sensitivity to lead poisoning and acute hepatic porphyria.Alternatively spliced transcript variants encoding different isoforms have been identified.