NRG2 is therefore an excellent potential functional as well as positional candidate gene for glaucoma at GLC1M. In the present study, we evaluated the role of the NRG2 gene in the JOAG family from whom the GLC1M locus was originally identified and unrelated JOAG patients, and further refined the linkage interval for GLC1M. This evidence concerns the gene EFNA5 and glaucoma.