Androgen insensitivity syndrome / AIS 2 (AR-related) - Warmblood horse

What does this test analyse?

This genetic test analyses the AR c.1630_1654del variant in Warmblood horses. The condition is also known as androgen insensitivity syndrome, AIS, AIS 2, testicular feminisation and 64,XY disorder of sex development.

What does it mean for the horse?

The AR gene encodes the androgen receptor, which is needed for normal response to male hormones during development. In genetic male horses, the tested deletion causes insufficient androgen response, so male sexual development does not proceed normally and the horse may appear externally female.

The test is useful for breeding decisions, infertility investigations and unexpected sex development in lines where this variant is relevant. Mares with one copy are carriers and can pass the variant on. A genetic male foal that inherits the variant develops AIS and is expected to be infertile.

Practical value of this test

• Detects the known AR c.1630_1654del deletion for AIS 2.
• Helps identify carriers before breeding.
• Provides targeted genetic clarity in abnormal or unclear sex development.
• Supports mating choices to avoid affected foals.

Inheritance and result

The variant is inherited as X-linked recessive. Female animals can be clear, carrier or rarely homozygous for the variant. Genetic male animals have one X chromosome; when that X chromosome carries the variant, it causes AIS.