Breeds Affected: Quarter Horse & related breeds
Samples Accepted: Blood, Hair
Disease Information: Incontinentia Pigmenti (IP) may be mistaken for a color pattern because affected animals have a striped appearance resembling the brindle pattern in dogs. Affected females develop skin lesions and also have irregular development of hooves, teeth, and eyes.
Inheritance Information: IP is X-linked dominant. The gene is located on the X-chromosome, and only one mutant allele is required to cause the disease.
The possible genotypes are:
XX This horse is a normal female.
XXIP This horse is an affected female. She will pass the mutation (XIP) to 50% of her offspring. She can become pregnant with foals of all four genotypes: normal female (XX), affected female (XXIP), normal male (XY), and affected male (XIPY). Affected male fetuses are not viable and are spontaneously aborted during pregnancy.
XY This horse is a normal male.
XIPY Horses with this genotype are not viable, and XIPY fetuses spontaneously abort during pregnancy. No live affected male foals are possible.
– To reduce the incidence of IP in a population, mares affected with IP should not be used for breeding.
Test Information: This mutation test identifies a single base change in the IKBKG gene.
Towers, R.E., Murgiano, L., Millar, D.S., Glen, E., Topf, A., Jagannathan, V., Drögemüller, C., Goodship, J.A., Clarke, A.J., Leeb, T.: A nonsense mutation in the IKBKG gene in mares with incontinentia pigmenti. PLoS One 8:e81625, 2013. Pubmed reference: 24324710. DOI: 10.1371/journal.pone.0081625.
Further information is available at the Online Mendelian Inheritance in Animals website.