CEA, which segregates in several herding breeds with Collie ancestry, was mapped to a large region of CFA37 that included
over 40 genes [92]; subsequently the fact that the disorder segregates in
multiple, closely related breeds was used to reduce the size of the critical disease - associated region and pinpoint the causal mutation to a 7.8 kb intronic deletion in the NHEJ1 gene, which spans a highly conserved binding
domain to which several developmentally important genes bind [91].