- Defects in TCIRG1 subunit of the vacuolar proton pump are responsible for a subset of human autosomal recessive osteopetrosis. Frattini, A., Orchard, P.J., Sobacchi, C., Giliani, S., Abinun, M., Mattsson, J.P., Keeling, D.J., Andersson, A.K., Wallbrandt, P., Zecca, L., Notarangelo, L.D., Vezzoni, P., Villa, A. Nat. Genet. (2000)