Nasal embryonic LHRH factor (NELF) mutations in patients with normosmic hypogonadotropic hypogonadism and Kallmann syndrome

Objective: To determine if mutations in NELF, a gene isolated from migratory GnRH neurons, cause normosmic idiopathic hypogonadotropic hypogonadism (IHH) and Kallmann syndrome (KS). Design: Molecular analysis correlated with phenotype. Setting: Academic medical center. Patient(s): A total of 168 IHH/KS patients as well as unrelated control subjects were studied for NELF mutations. Intervention(s): NELF coding regions/splice junctions were subjected to polymerase chain reaction (PCR)-based DNA sequencing. Eleven additional IHH/KS genes were sequenced in three patients with NELF mutations. Main Outcome Measure(s): Mutations were confirmed by sorting intolerant from tolerant, reverse-transcription (RT)-PCR, and Western blot analysis. Result(s): Three novel NELF mutations absent in 372 ethnically matched control subjects were identified in 3/168 (1.8%) IHH/KS patients. One IHH patient had compound heterozygous NELF mutations (c.629-21G>C and c.629-23C>G), and he did not have mutations in 11 other known IHH/KS genes. Two unrelated KS patients had heterozygous NELF mutations and mutation in a second gene: NELF/KAL1 (c.757G>A; p.Ala253Thr of NELF and c.488-490delGTT; p.Cys163del of KAL1) and NELF/TACR3 (c.1160-13C>T of NELF and c.824G>A; p.Trp275X of TACR3). In vitro evidence of these NELF mutations included reduced protein expression and splicing defects. Conclusion(s): Our findings suggest that NELF is associated with normosmic IHH and KS, either singly or in combination with a mutation in another gene.