The phenotypes of Prokr2 and Prok2 knockout mice model aspects of human Kallman syndrome (KS), a partially penetrant genetic disease that causes OB deformity and consequently anosomia and hypogonadism with associated sterility and failure to reach puberty (Ng et al., 2005; Matsumoto et al., 2006). The gene discussed is PROK2; the disease is hereditary disease.