logo
Horse Genetics / Horse Health / Androgen Insensitivity Syndrome

Androgen Insensitivity Syndrome (AIS)

Gene or Region: AR

Reference Variant: A

Mutant Variant: G

Affected Breeds: Quarter Horses

Research Confidence: High - Findings supported by other species

Explanation of Results: AIS/AIS = homozygous for Androgen Insensitivity Syndrome, not observed AIS/n (female) = heterozygous for Androgen Insensitivity Syndrome, female carrier AIS/n (male) = heterozygous for Androgen Insensitivity Syndrome, sterile and phenotypically female n/n = no variant detected

General Description

Androgen Insensitivity Syndrome (AIS), previously known as Testicular Feminization Syndrome, is a disorder of sexual development in which a horse with a XY SRY+ karyotype appears female. Horses with AIS exhibit stallion-like behaviors, have external female genitalia, and often internal un-descended testicles.

AR is a steroid-activated transcription factor that plays a key role in normal sexual development. Mutations in other species have been noted to cause AIS and have been associated with prostate cancer. This particular mutation is a single base change that alters the start codon of the encoded protein. Though normal transcription and translation still occurs, the encoded protein likes has an altered function.

References

Révay T et al., “GTG mutation in the start codon of the androgen receptor gene in a family of horses with 64,XY disorder of sex development.” (2012) Sex Dev. 6: 108-16. PMID: 22095250

BACK TO HORSE HEALTHNEXT