ExperimentName: Horse model of TRPM1 loss-of-function
NonHumanModel: Equus ferus caballus
GeneAlteration: The horse has homozygous disruption of the TRPM1 gene by a naturally occurring insertion of a 1378 bp transposon in intron 1 (g. 108,297,929_108,297,930 ins1378). A previous publication by the same group has shown that TRPM1 expression is absent from the skin and retina of these horses (PMID: 18660533).
ModelPhenotype: HP:0001053 (Hypopigmented skin patches), HP:0000591 (Abnormal sclera morphology), HP:0000662 (Nyctalopia), HP:0007984 (Electronegative electroretinogram),
HumanPhenotype: HP:0000662 (Nyctalopia), HP:0000545 (Myopia), HP:0000572 (Visual loss), HP:0007984 (Electronegative electroretinogram), HP:0000958 (Dry skin), HP:0000964 (Eczema)
ModelEvidence: The affected horses exhibit night blindness and abnormal dark-adapted ERG with absent b-wave and increased amplitude of a-wave (Figure 1). Both phenotypes are similar to the affected human patients. Melanocyte dysfunction is also shown by unpigmented areas of the skin (Figures 1 and 2) and the sclera of the eye (Figure 2A). These pigment phenotypes do not have a human equivalent, although some affected patients have been reported to have dry skin or a history of eczema (PMID: 19878917).
ModelVariant: The model harbors a naturally occurring variant that does not have an equivalent / orthologous variant reported in human patients.