Congenital smell loss – a genetic disorder of decreased cell growth and increased cell death determined by biochemical measurements in nasal mucus

Abstract

Congenital smell loss is a genetic disorder which affects about 400,000 people in the US and is characterized by inability to recognize any environmental odor. About 12% of patients with this disorder have abnormal olfactory nerves and olfactory epithelia and other congenital abnormalities involving endocrine, brain and renal systems. About 88% of patients with this disorder have olfactory bulbs, grooves and olfactory epithelia. To understand the biochemical basis of this genetic disorder we measured several proteins and signal substances in nasal mucus in the larger group of patients with congenital smell loss using a 96 plate colorimetric ELISA assay and compared these results with normal subjects. In patients, nasal mucus growth factors cAMP and cGMP were significantly lower than in normals whereas the apoptotic factor TRAIL was significantly higher. These results indicate that there are at least two congenital biochemical defects in this larger group of patients responsible for their congenital smell loss: decreased nasal mucus growth factors and increased apoptotic “death factors”. Treatment of these patients with phosphodiesterase (PDE) inhibitors increased nasal mucus concentrations of cAMP and has been partially successful in initiating smell function in some patients. Treatment with both TNFα inhibitors, which inhibits nasal mucus TRAIL secretion, and PDE inhibitors has not been attempted. These biochemical markers are the first to characterize genetically related biochemical abnormalities in the majority of patients with congenital loss of smell.