- Human calcium-activated potassium channel gene KCNN4 maps to chromosome 19q13.2 in the region deleted in diamond-blackfan anemia. Ghanshani, S., Coleman, M., Gustavsson, P., Wu, A.C., Gargus, J.J., Gutman, G.A., Dahl, N., Mohrenweiser, H., Chandy, K.G. Genomics (1998)