Several genes and/or loci are reported to be causative and are referred to as GLC (glaucoma) loci; for example, CYP1B1 [6] is located at the GLC3A locus (2p21) [7], and LTBP2 is located at the GLC3D locus (14q24.3) [8]. The gene discussed is CYP1B1; the disease is glaucoma.