Animal Health Trust reports interim statistics from its DNA study of Episodic Falling Syndrome in the cavalier King Charles spaniel. One out of five cavaliers were found to carry the defective gene.

As of May 15, 2012: 2,811 cavaliers have been DNA-tested for episodic falling syndrome, of which 104 (3.7%) have been found to be "affected" with two of the mutated EFS gene, 605 (21.52%) are "carriers" with only one of the mutated gene, and the rest, 2,102 (74.78%), are clear of the defective gene.

http://www.cavalierhealth.org/episod...of_DNA_testing