Congenital hydrocephalus associated with a nonsense variant in B3GALNT2 (O-glycan synthesis), with CSF accumulation and ventricular dilatation. It causes a domed skull, a wide fontanelle and neurological signs; often severe or lethal in the perinatal period. Inheritance probably autosomal recessive. The test is complementary to the clinical examination and imaging studies.

Tiro belga, Frisón and Warmblood. Frequencies: limited data.

- Domed skull and wide sutures
- Open fontanelle in the foal
- Depression of consciousness and lethargy
- Seizures and visual disturbances
- Ataxia and perinatal death in severe cases

The dossier records OMIA:000487 and the variant B3GALNT2 NC_009144.3:g.76887901C>T (c.1423C>T; p.Gln475Ter; rs3429464524). No author or year is stated.

- Genotype breeding animals of predisposed breeds
- Avoid matings between carriers if recessive inheritance is confirmed
- Do not breed animals with confirmed hydrocephalus
- Record cases and review pedigrees

Differential diagnosis with secondary hydrocephalus (infectious/traumatic), CNS malformations and neonatal metabolic encephalopathies. Complementary: transfontanellar ultrasound and cranial CT/MRI.

1. OMIA:000487 Hidrocefalia del caballo