Abiotrofia cerebelosa - CA
Prueba de ADN para Abiotrofia Cerebelosa (CA) – Caballos árabes puros y mestizos. Esta prueba verifica la presencia de la mutación...
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Acerca de la prueba
Prueba de ADN para Abiotrofia Cerebelar (AC) – Caballos árabes puros y mestizos.
Esta prueba verifica la presencia de la mutación recesiva AC.
¿Por qué probar?
Esta prueba de ADN determina el estado claro, portador o afectado de CA. Se pueden tomar decisiones informadas para las selecciones de cría y prevenir el nacimiento de potros afectados.
A veces se confunde CA con el síndrome del tambaleo, la Mieloencefalitis Protozoaria Equina (EPM) y problemas relacionados con lesiones, como una conmoción cerebral, por lo que esta prueba de ADN podría ayudar en el diagnóstico.
Signos clínicos
Signs appear only in foals that inherited the change from both parents. An affected foal looks normal at birth. Signs usually appear between about six weeks and four months old, sometimes as early as four weeks, sometimes as late as six months or a little beyond. A group of nerve cells in the part of the brain that controls balance dies off after birth. The brain does not shrink noticeably; the cells that matter just stop working.
- A head tremor that appears when the horse concentrates on doing something
- Poor balance and coordination
- An exaggerated, paddling action of the front legs
- Standing with the legs splayed wide apart
- No blink when a hand is moved quickly towards the eye
- Startling easily and falling over, and often being unable to get up again
Severity varies enormously. Some affected horses shake almost constantly, cannot keep their balance and are extremely difficult to handle. Others cope well, with the odd misstep and a very slight tremor. Nine horses with two copies were found whose owners had never noticed anything wrong.
The condition gets worse over time but does not itself kill. In one published series of 29 affected horses, 25 were put down at their owners' request once signs appeared, because a horse that cannot keep its feet is dangerous to itself and to the people handling it.
None of these signs is unique to CA. Before the DNA test existed, the only certain diagnosis was after death, by examining the brain. The diagnosis is made by a veterinarian, combining the history, a neurological examination, scans where needed and this genetic result.
Transmisión
CA is recessive. A foal needs one copy from the sire and one from the dam to be affected. One copy makes a horse a carrier, never a patient. The gene is not on a sex chromosome, so colts and fillies are affected equally.
What each mating can produce:
- n/n x n/n gives 100% n/n
- n/n x n/CA gives 50% n/n, 50% n/CA
- n/n x CA/CA gives 100% n/CA
- n/CA x n/CA gives 25% n/n, 50% n/CA, 25% CA/CA
- n/CA x CA/CA gives 50% n/CA, 50% CA/CA
- CA/CA x CA/CA gives 100% CA/CA
Prevención
Prevention is a breeding decision.
Breeding. Test breeding stock before mating and never mate two carriers. A carrier mated to a partner that tested negative produces no affected foals, although some foals will be carriers.
Keeping valuable lines. Carriers are common in Arabians, so excluding every carrier would narrow the gene pool sharply. Mate carriers only with partners that tested negative and test every foal. This keeps the lines available while the change is bred out.
Managing an affected horse. No treatment reverses the condition. Decisions about handling, safety and suitability for work are a matter for your veterinarian.
Resultados
La prueba de ADN verifica la presencia de la mutación recesiva CA y presenta los resultados como uno de los siguientes:
- N/ – Negativo para CAAusencia del alelo responsable de CA.
- N/CA– Portador - Heterocigoto positivo para CA. Presencia de una copia del alelo responsable de CA. El caballo es portador del trastorno CA y puede transmitir una copia del alelo CA al 50% de su descendencia cuando se reproduce.
- CA/– Afectado - Homocigoto positivo para CAPresencia de dos copias del alelo responsable de CA. El caballo está afectado por el trastorno CA y puede transmitir el alelo CA al 100% de su descendencia cuando se reproduce.
Requisitos de muestra
30 a 40 - raíces del cabello - sobre o 5 mL - sangre - tubo K3 EDTA
Envía tu muestra por correo ordinario o entrega exprés a:
Laboratorio Equigerminal HIESE
Rua da Quinta do Sobreiro Nº25
3230-343 Penela, Portugal
Tiempo de entrega
2 a 5 días hábiles
Cómo funciona
🛒 Purchase the test: select and buy the test online.
📧 Receive instructions: after payment confirmation you receive sample collection instructions by e-mail.
✨ Collect the sample yourself: pull 20 to 40 hair roots with the bulb attached, or ask your veterinarian to collect blood in a K3-EDTA tube.
📄 Complete the form: print and complete the submission form with the animal identification.
📮 Send it to the laboratory: Equigerminal, S.A., HIESE, Rua da Quinta do Sobreiro, 25, Quinta Vale do Espinhal, 3230-343 Penela, PORTUGAL.
📄 Receive your report: your certified report is issued as soon as the analysis is validated.
Preguntas frecuentes
At what age can a horse be tested?
Any age. The genotype is fixed at conception and never changes, so one test lasts for life.
How certain is this test?
The gene change tested is the best and only candidate found for CA, and in the horses studied it matched the disease every time. The final laboratory proof that it causes the disease is still missing, so researchers call it a probable cause rather than a proven one.
Does a negative result rule out a balance problem?
No. The test looks for CA only. It does not detect SCID, Lavender Foal Syndrome or any other condition, and a horse that tests negative can still have a nerve or brain disease from another cause.
For Professionals
Genetic and clinical detail for veterinarians, geneticists and laboratories.
- Gene / locus: TOE1 (target of EGR1, exonuclease), exon 4, ECA2; the variant lies about 1,200 bp upstream of MUTYH (mutY DNA glycosylase), adjacent to a putative GATA2 binding site (Brault et al., 2011). Mapped, in four Arabian families descending from common sires, to a conserved homozygous region of about 142 kb containing four genes.
- Variant: R95H (Arg95His), missense in TOE1. HGVS (EquCab3.0): NC_009145.3:g.13122415C>T; XM_001496197.5:c.284G>A; XP_001496247.1:p.(Arg95His). In silico prediction: probably damaging to TOE1.
- Alternative designations: EquCab2.0 ECA2:13074277G>A. Ensembl ENSECAT00000024892.2:c.284G>A / ENSECAP00000020698.1:p.Arg95His; the same position is intronic in another transcript (ENSECAT00000009202.3:c.541-13539C>T). The OMIA variant table files the variant under MUTYH while the curated OMIA phene text and the primary article place it in TOE1 exon 4.
- Causal status: Brault et al. (2011) call it a potential, not proven, causal variant; the published test reads it together with adjacent markers. It was the only candidate found, concordant with disease in all horses studied, and restricted to Arabian-derived horses; a companion study argues more strongly for it on the grounds that it arose in Arabians and is absent from other breeds without Arabian blood. Functional proof is lacking.
- Variant identifiers: rs397160943 (EVA); OMIA variant 437; phene OMIA:000175-9796.
- Variant classification: not currently evaluated (ISAG/AVCG, per OMIA).
- Inheritance: autosomal recessive (OMIA code R); complex segregation analysis of 804 Arabians including 29 affected, no sex effect (Brault, Famula and Penedo, 2011).
- Penetrance / expressivity: no healthy homozygote was found in the discovery work. MUTYH expression was reduced in affected cerebellum by qPCR, proposed as the mechanism (Brault et al., 2011; Scott et al., 2018), whereas whole-transcriptome analysis found neither TOE1 nor MUTYH differentially expressed, so both remain candidates (Scott et al., 2017). Biallelic TOE1 variants cause pontocerebellar hypoplasia in 12 human families, affecting the same functional region of the protein (Lardelli et al., 2017).
- Breeds with documented carriers or cases: Arabian and Arabian crosses, with affected foals in Polish, Egyptian and Spanish Arabian types; carriers with the full Arabian CA haplotype in Trakehner and Welsh Pony (carriers at least half Arabian) and Bashkir Curly (traced to one Arabian stallion used in the 1960s) (Brault and Penedo, 2011). OMIA also lists Quarter Horse, from a supplementary table of Durward-Akhurst et al. (2024), not a CA-specific study. Clinically and histologically diagnosed cases without genotype in an Icelandic horse (Hansen et al., 2022) and a Quarter Horse foal (Primo et al., 2025). Miniature Horse and Gotland Pony, sometimes listed elsewhere, have no published support; 106 Miniature Horses tested clear.
- Allele / carrier frequencies: carrier and allele (gene-copy) figures differ by roughly half and are not interchangeable. Arabian carrier frequency 19.7% (allele frequency about 10.5%) among more than 4,200 Arabians submitted for testing, of which 1.4% were affected, with possible line-selection bias; 3 carriers in 41 randomly chosen control Arabians (Brault and Penedo, 2011). 26.9% carriers in a family study of 804 Arabians (Brault, Famula and Penedo, 2011). South Africa: 5.1% carriers (95% CI 2.5 to 9.1%) in the 2009/10 purebred Arabian foal crop, unchanged from 2004/5 (Tarr et al., 2014). Poland: a low figure among 808 elite Arabians. Non-Arabian breeds: initial screen of 1,845 horses from 31 breeds found 6 carriers (2 Trakehner, 1 Welsh Pony, 3 Bashkir Curly); follow-up carrier frequencies Bashkir Curly 8/143 (5.6%, allele 2.8%), Trakehner 2/147 (1.4%, allele 0.68%), Welsh Pony 1/150 (0.7%, allele 0.33%); clear in 172 Thoroughbreds, 106 Miniature Horses, 102 Quarter Horses, 86 Percherons, 86 Paso Finos, 82 Standardbreds, 82 Tennessee Walking Horses, 70 Morgans, 70 Lipizzaners and 70 Norwegian Fjords, among others; groups of this size cannot exclude a very rare allele (Brault and Penedo, 2011).
- Clinical / diagnostic notes for veterinarians: post-natal Purkinje cell degeneration; intention head tremor, ataxia, exaggerated or paddling foreleg action, wide-based stance, absent menace response (Brault et al., 2011). Conclusive diagnosis is post-mortem cerebellar histopathology; morphometric MRI has been evaluated as an ante-mortem aid (Cavalleri et al., 2013); neither is part of this test. A CA/CA genotype supports but does not by itself prove the diagnosis, given the associative status of the marker.
Key references:
- Brault LS, Cooper CA, Famula TR, Murray JD, Penedo MCT (2011). Mapping of equine cerebellar abiotrophy to ECA2 and identification of a potential causative mutation affecting expression of MUTYH. Genomics 97:121-129. doi:10.1016/j.ygeno.2010.11.006. PMID 21126570.
- Brault LS, Penedo MCT (2011). The frequency of the equine cerebellar abiotrophy mutation in non-Arabian horse breeds. Equine Vet J 43:727-731. doi:10.1111/j.2042-3306.2010.00349.x.
- Brault LS, Famula TR, Penedo MCT (2011). Inheritance of cerebellar abiotrophy in Arabians. Am J Vet Res 72:940-944.
- Tarr CJ, Thompson PN, Guthrie AJ, Harper CK (2014). The carrier prevalence of severe combined immunodeficiency, lavender foal syndrome and cerebellar abiotrophy in Arabian horses in South Africa. Equine Vet J 46:512-514. doi:10.1111/evj.12177. PMID 24033554.
- Cavalleri JMV, Metzger J, Hellige M, Lampe V, et al. (2013). Morphometric magnetic resonance imaging and genetic testing in cerebellar abiotrophy in Arabian horses. BMC Vet Res 9:105. doi:10.1186/1746-6148-9-105.
- Scott EY, Penedo MCT, Murray JD, Finno CJ (2017). Defining trends in global gene expression in Arabian horses with cerebellar abiotrophy. Cerebellum 16:462-472. doi:10.1007/s12311-016-0823-8.
- Scott EY, Woolard KD, Finno CJ, Penedo MCT, Murray JD (2018). Variation in MUTYH expression in Arabian horses with cerebellar abiotrophy. Brain Res 1678:330-336. doi:10.1016/j.brainres.2017.10.034.
- Lardelli RM, Schaffer AE, Eggens VRC, et al. (2017). Biallelic mutations in the 3-prime exonuclease TOE1 cause pontocerebellar hypoplasia and uncover a role in snRNA processing. Nat Genet 49:457-464. doi:10.1038/ng.3762.
- Hansen S, Olsen E, Raundal M, Agerholm JS (2022). Cerebellar abiotrophy in an Icelandic horse. Acta Vet Scand 64:31. doi:10.1186/s13028-022-00651-0.
- Primo ALM, Assis DM, Santos VGS, et al. (2025). Cerebellar abiotrophy in a quarter horse foal. J Equine Vet Sci 147:105386. doi:10.1016/j.jevs.2025.105386.