To date, mutations in FGFR1 account for less than 10% of patients with congenital hypogonadotropic hypogonadism (CHH) involving KS and nIHH [19], and among them, even fewer have undergone functional analysis, and thus, the correlation between phenotype and genotype cannot be clearly verified. This evidence concerns the gene FGFR1 and cartilage-hair hypoplasia.