Center for Human Genetic Research and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Simches Research Building, 185 Cambridge Street, Boston, MA 02114, USA.
Complex regulatory mechanisms lead to the expression in each olfactory neuron of one allele of only one of the 1000 odorant receptor (OR) genes. In this issue, Nguyen et al. (2007) provide evidence that regulatory elements residing within the coding region of OR genes are involved in the singularity of OR gene expression.