- Mutations in SLC4A4 cause permanent isolated proximal renal tubular acidosis with ocular abnormalities. Igarashi, T., Inatomi, J., Sekine, T., Cha, S.H., Kanai, Y., Kunimi, M., Tsukamoto, K., Satoh, H., Shimadzu, M., Tozawa, F., Mori, T., Shiobara, M., Seki, G., Endou, H. Nat. Genet. (1999)