D05EQ-615: Biochemical Characterization of Hyperelastosis Cutis: Investigating the Collagen Crosslink Pattern that Identifies Affected Horses

principal investigator: Ashley Hill, student, Mississippi State University

Project Mentor: Cyprianna Swiderski, DVM, PhD

completed

Year: 1 of 1. $0

Hyperelastosis Cutis (aka HERDA) is a genetic disease of Quarter Horses that is recognized by bruising, stretching, sloughing, and severe scarring of skin. This laboratory previously identified an elevated deoxypyridinoline (DPD) to pyridinoline (PYD) ratio in the urine that identifies affected horses from birth. DPD and PYD crosslink collagen, giving strength to the collagen in skin. Synthesis of both DPD and PYD require the amino acid hydroxylysine (HL) which is derived from its precursor amino acid, lysine. Depleting HL favors DPD formation. This study determined that horses with HERDA have less HL available and therefore fewer PYD crosslinks in collagen. Lysine levels were not different between affected and normals, indicating that conversion of lysine to hydroxylysine is defective in horses with HERDA. These results are important in determining which of the emerging genetic defects in horses with HERDA actually causes the disease.

Ashley says, "This project is important to me because we achieved publishable data which helped to elucidate the genetic defect responsible for Hyperelastosis Cutis without inducing significant stress on the animals nor requiring euthanasia as an endpoint."