Congenital malformation of the craniocervical junction (fusion of the atlas to the occipital bone with atlantoaxial instability) associated with a ~2.7 kb deletion in the HOXD3/HOXD4 region. It may cause neurological signs due to spinal cord compression. The test is complementary to the clinical examination and imaging studies.

Árabe. Frequencies: limited data.

- Ataxia and tetraparesis of congenital or progressive onset
- Abnormal posture of the head and neck (torticollis)
- Cervical pain and stiffness
- Proprioceptive deficits

The dossier records OMIA:000081 and the ~2.7 kb deletion on chromosome 18 (Chr18:54616748-54619464, EquCab2.0), 4.4 kb downstream of HOXD4 and 8.2 kb upstream of HOXD3. No author or year is stated.

- Confirm the genetic status of breeding animals before mating
- Do not breed animals with neurological signs or malformation confirmed by imaging
- Review pedigrees of Arabian lines with cases of cervical ataxia

Differential diagnosis with hereditary ataxia (SCA/CA), Chiari malformation, cervical stenosis and traumatic vertebral subluxation. Complementary: cervical radiography, CT/MRI and neurological examination.

1. OMIA:000081 Fusión atlanto-occipital del caballo