- Chromosomal location of two human genes encoding tetrahydrobiopterin-metabolizing enzymes: 6-pyruvoyl-tetrahydropterin synthase maps to 11q22.3-q23.3, and pterin-4 alpha-carbinolamine dehydratase maps to 10q22. Thöny, B., Heizmann, C.W., Mattei, M.G. Genomics (1994)