Test Detail
Androgen insensitivity AR2–AR6 (androgen receptor) — several breeds
Reproductive · Horse
Same syndrome as AR1 (testicular feminisation due to androgen receptor dysfunction) caused by additional variants AR2, AR3, AR4, AR5 and AR6 of the AR gene. XY animals with a female phenotype and infertility. X-linked recessive inheritance. The test is complementary to the clinical examination and karyotyping.
Incidence
Thoroughbred (AR2, AR5, AR6), Warmblood (AR3) and Tennessee Walking Horse (AR4). Frequencies: limited data.
Clinical signs
- Female phenotype with XY karyotype
- Infertility and absence of ovarian function
- Testicular gonads frequently ectopic
- Infertility and absence of ovarian function
- Testicular gonads frequently ectopic
History
The dossier records variants AR2 (Thoroughbred), AR3 (Warmblood), AR4 (Tennessee Walking Horse), AR5 (Thoroughbred) and AR6 (Thoroughbred, splicing). No author or year is stated.
Breeder management
- Genotype carrier mares
- Avoid matings that generate affected males
- Withdraw confirmed carriers from risk breeding programmes
- Confirm the karyotype in discordant phenotypes
- Avoid matings that generate affected males
- Withdraw confirmed carriers from risk breeding programmes
- Confirm the karyotype in discordant phenotypes
Specialist notes
Differential diagnosis with AR1, XY sex reversal (SRY) and mosaicism. Complementary: karyotype and gonadal ultrasound.
References
1. OMIA:000991 Insensibilidad a andrógenos del caballo (variantes AR2–AR6)
Price: 85,54 € · Turnaround time: 30 days