GNRH1 and hypoalphalipoproteinemia, primary, 1: In contrast, G4 patients, with only monoallelic mutations, demonstrated a greater diversity of clinical phenotypes, ranging from severe GnRH deficiency such as KS and IHH to mild GnRH deficiency such as FHA, adult-onset IHH, or constitutional delay of puberty, to normal GnRH function.