Screening for variability in the ciliary neurotrophic factor (CNTF) gene: no evidence for association with human obesity.

Systemic administration of the neurocytokine ciliary neurotrophic factor (CNTF) normalizes the obese phenotype of ob/ob and db/db mice. CNTF exerts its multiple effects through a receptor complex whose sequence, localization in hypothalamic nuclei and mode of signal transduction share remarkable similarities with the leptin receptor. In the human CNTF gene, a mutation in the first intron creates a new splice acceptor site, with the resulting mRNA coding for an aberrant protein (Takahashi et al., 1994). Given the potential of CNTF to influence energy homeostasis, this study was undertaken to determine whether variability in the CNTF gene is associated with human obesity. The previously described mutation was found in 30.3% of obese children and adolescents, 7 of which were homozygous (allele frequency 0.163). 29.5% of lean subjects carried the mutation, none of which were homozygous (allele frequency 0.148; corrected p = 1 compared to obese). No further mutations were detected by single strand conformational polymorphism (SSCP) analysis. In conclusion, variants in the CNTF gene are unlikely to be associated with the development of early-onset obesity.