- Mutations in fibroblast growth factor receptor 1 cause both Kallmann syndrome and normosmic idiopathic hypogonadotropic hypogonadism. Pitteloud, N., Acierno, J.S., Meysing, A., Eliseenkova, A.V., Ma, J., Ibrahimi, O.A., Metzger, D.L., Hayes, F.J., Dwyer, A.A., Hughes, V.A., Yialamas, M., Hall, J.E., Grant, E., Mohammadi, M., Crowley, W.F. Proc. Natl. Acad. Sci. U.S.A. (2006)