 The gene to which "Lp" has now been localized encodes a protein that channels calcium ions, a key factor in the transmission of nerve impulses.This protein, which is found in the retina and the skin, existed in fractional percentages of the normal levels in homozygous "Lp/Lp" horses.A 2008 study theorizes that both CSNB and leopard complex spotting patterns are linked to the TRPM1 gene.