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Incontinentia Pigmenti (IP Horse)

Coat pattern with negative effects on skin, coat, teeth and eyes


  • Pattern following the lines of Blaschko (going down from the spine on each side of the horse)
  • Anomalies of eyes, teeth and hooves
  • Hairless patches distributed over entire body
  • Itchy skin lesions

General Information

  • IP may be mistaken for a “normal” pattern.
  • Mares show sparse mane and tail.
  • Symptoms manifest themselves over time.
  • Stallions with this variant will be aborted during pregnancy.

Breeds affected

Quarter Horse and related breeds

Test Information

This test detects the change of a single basepair in the IKBKG gene.

Genotype and Lab Report

Inheritance: X-linked dominant

→ The variant affects the X chromosome. Females have two copies of the X chromosome, therefore when one of the two is mutated, the effects are not extreme. Males have only one X chromosome, so having one mutated variant causes severe symptoms. Male foals do not develop to term.




X/X = normal mare

The mare has no copies of the genetic variant causitive for IP and therefore cannot pass it on to her offspring.


XIP/X = affected mare (heterozygous)

The genetic variant will be passed on to offspring with a probability of 50%. These foals will also be carriers or affected.


X/Y = normal stallion

The stallion has no copies of the genetic variant causitive for IP and therefore cannot pass it on to his offspring.


XIP/Y = affected stallion (homozygous)

The foal is affected and will be aborted during pregnancy.


To reduce distribution of IP, affected mares (XIP/X) should not be used for breeding.


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 Online Mendelian Inheritance in Animals.

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