A trend in the increase of serum ephrin-A5 content related to Gleason score (data not shown) and a higher serum ephrin-A5 content in metastatic PCa patients than non-metastatic PCa patients imply that serum ephrin-A5 protein level could be a potent marker for PCa metastasis. The gene discussed is EFNA5; the disease is posterior cortical atrophy.