Deficiencia de la enzima ramificadora de glucógeno - GBED
Prueba de ADN para la deficiencia de la enzima ramificadora de glucógeno (GBED). Esta prueba de ADN verifica la presencia del...
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Acerca de la prueba
La Prueba de ADN para la Deficiencia de la Enzima Ramificante del Glucógeno (GBED) detecta la mutación recesiva responsable de la Deficiencia de la Enzima Ramificante del Glucógeno, un trastorno hereditario fatal que afecta el metabolismo del glucógeno.
GBED se hereda como un rasgo autosómico recesivo. Los caballos portadores son clínicamente normales pero pueden transmitir la mutación a su descendencia. Los potros que heredan dos copias de la mutación no pueden almacenar glucógeno correctamente, lo que resulta en aborto, mortinato o muerte poco después del nacimiento.
La prueba de ADN permite a los criadores identificar a los portadores y tomar decisiones de cría informadas para prevenir potros afectados.
¿Por qué probar?
La prueba de GBED permite a los criadores:
- Identificar caballos portadores clínicamente normales.
- Prevenir apareamientos entre portadores.
- Reducir el riesgo de abortos y potros afectados.
- Confirmar casos sospechosos de GBED en potros.
- Apoyar programas de cría responsables.
GBED se encuentra más comúnmente en Quarter Horses, Paint Horsesy razas relacionadas.
Signos clínicos
Many affected foals are aborted or born dead. Of those born alive, most died or were put down by 8 weeks old in the published cases, and none has been found to live past 18 weeks.
- Abortion late in the pregnancy, a foal born dead, or a foal born early
- Weakness all over, unable to stand or to suck, lying down and not getting up
- Legs that come up bent and contracted, which then straighten out again
- Fits, in some foals because the blood sugar has fallen too low
- Fast breathing and a fast heart, breathing failure, an irregular heartbeat, and sudden death, including after exercise
- On blood tests: a low white cell count, raised muscle enzymes, and blood sugar that keeps dropping
- After death the organs look almost normal to the eye
None of these signs is unique to GBED, and it is easily mistaken for other newborn diseases. Your veterinarian or a pathologist makes the diagnosis.
Transmisión
GBED is recessive. A foal needs one copy from the sire and one from the dam to be affected. 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/GBED gives 50% n/n, 50% n/GBED
- n/GBED x n/GBED gives 25% n/n, 50% n/GBED, 25% GBED/GBED
Affected foals never reach breeding age, so in practice no mating involves a GBED/GBED parent.
Prevención
There is no treatment, so prevention is a breeding decision.
Breeding. Mate a carrier only with a partner that tested negative, and test every foal. No affected foals are born, though some foals will be carriers. This keeps a valuable line while the variant is bred out. Being a carrier is not by itself a reason to stop breeding a horse.
An affected foal. Nothing changes the outcome. Your veterinarian guides supportive care and welfare decisions.
Resultados
La prueba de ADN verifica la presencia de los alelos recesivos GBED y presenta los resultados como uno de los siguientes:
- N/ - Negativo para GBED. Ausencia del alelo defectuoso responsable de GBED.
- GBED/N - Portador - Heterocigoto positivo para GBED. Presencia de una copia del alelo responsable de GBED. El caballo es portador de GBED y puede transmitir una copia del alelo GBED a su descendencia cuando se reproduce.
- GBED/ -Afectado - Homocigoto positivo para GBED. Presencia de dos copias del alelo responsable de GBED. El animal está afectado por el trastorno GBED. GBED es letal causando aborto y/o mortalidad neonatal.
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
🛒 Compra el Test: Selecciona y compra el test en línea.
📧 Recibe Instrucciones: Después de la confirmación del pago, recibe instrucciones para la recolección de la muestra.
✨ Recolección de Muestra: Recoge 30–40 raíces de cabello o pide a tu veterinario que tome una muestra de sangre.
📄 Descarga el Formulario de Envío: Descarga el formulario de envío imprimible.
📮 Envía las Muestras: Envía a:
Equigerminal Lab HIESE
Rua da Quinta do Sobreiro Nº25
3230-343 Penela, Portugal
📄 Recibe Resultados: Tu certificado de ADN será enviado por correo electrónico.
Preguntas frecuentes
¿Qué es GBED?
GBED (Deficiencia de la Enzima Ramificante del Glucógeno) es un trastorno hereditario fatal que impide el almacenamiento normal de glucógeno, lo que conduce a una grave deficiencia de energía.
¿Pueden los caballos portadores desarrollar la enfermedad?
No. Los caballos portadores (N/GBED) están clínicamente sanos pero pueden transmitir la mutación a su descendencia.
¿Cómo se hereda GBED?
GBED sigue un patrón de herencia autosómico recesivo. Un potro afectado debe heredar una copia mutada de cada padre.
¿Qué razas deben ser analizadas?
Se recomienda encarecidamente realizar pruebas en Quarter Horses, Paint Horsesy razas relacionadas debido a la frecuencia relativamente alta de portadores.
¿Por qué los criadores deben realizar esta prueba?
Las pruebas de ADN identifican a los portadores antes de la reproducción, permitiendo decisiones de apareamiento informadas que previenen abortos y el nacimiento de potros afectados, mientras se preservan líneas genéticas valiosas.
For Professionals
Genetic and clinical detail for veterinarians, geneticists and laboratories.
- Gene / locus: GBE1 (1,4-alpha-glucan branching enzyme 1), ECA26.
- Variant: c.102C>A, nonsense (premature stop codon), no functional enzyme. HGVS (EquCab3.0): NC_009169.3:g.8667651C>A; NM_001081940.2:c.102C>A; NP_001075409.1:p.(Tyr34*).
- Alternative designations: Y34X; equine glycogen storage disease type IV (GSD IV), the same disease as GSD IV in humans. Laboratory allele symbol: GBED.
- Variant identifiers: rs3437568674 (EVA); OMIA variant 322.
- Variant classification: Pathogenic (P), ISAG/AVCG classification as listed in OMIA.
- Mechanism: without branching enzyme, glycogen cannot be packed into its branched storage form; an abnormal, poorly branched polysaccharide that cannot be broken down accumulates in skeletal muscle, heart, liver and brain.
- Inheritance: autosomal recessive, lethal; pedigree and genotype data consistent with a single founder (Wagner et al., 2006). OMIA code: A (autosomal).
- Penetrance / expressivity: homozygotes: abortion, stillbirth or neonatal death. About 2.5% of aborted and neonatal foals of Quarter Horse-related breeds submitted to two US diagnostic laboratories were homozygous, most of them abortions; characteristic deposits were found retrospectively in 8 of 9 affected foals (Wagner et al., 2006). In the first published series, related Quarter Horse foals all died by 7 weeks: stillbirth, transient flexural deformities, seizures, respiratory or cardiac failure, or persistent recumbency (Valberg et al., 2001).
- Breeds with documented carriers or cases: Quarter Horse and American Paint Horse (OMIA variant record); Quarter Horse-related breeds and crosses, including Appendix Quarter Horses; confirmed in Brazilian Quarter Horses (Araujo et al., 2018). Not found in 227 Thoroughbreds (Wagner et al., 2006). Appaloosas and Ponies of the Americas are often tested because of Quarter Horse ancestry, but no confirmed carrier is known in a published study.
- Allele / carrier frequencies: carrier frequency 8.3% of 338 Quarter Horses, 7.1% of 197 Paint Horses, 0% of 227 Thoroughbreds (Wagner et al., 2006). Allele frequency 5.4% in 200 control Quarter Horses and 13.2% in western pleasure horses (Tryon et al., 2009). Carrier frequency 7.94% of 742 Brazilian Quarter Horses competing in cutting, halter, racing, reining and barrel racing (Araujo et al., 2018). Allele frequency 10.9% in elite reining Quarter Horses, unchanged over time in the random cohort (Brown et al., 2026; 300 performance and 300 random horses born 2020 to 2024). Carrier and allele frequencies are not interchangeable; for a rare recessive the allele figure is roughly half the carrier figure.
- Clinical / diagnostic notes for veterinarians: consider GBED in abortion, stillbirth or weak neonates of Quarter Horse and Paint lineage. Abnormal polysaccharide deposits in cardiac muscle, skeletal muscle and liver are easily missed unless periodic acid-Schiff (PAS) staining is used; the heart is the most reliable site, but at least one confirmed affected foal showed no deposits. Erythrocyte branching-enzyme activity (about half-normal in carriers) gave only an indication and has been superseded by DNA testing.
Key references:
- Ward TL, Valberg SJ, Adelson DL, Abbey CA, Binns MM, Mickelson JR (2004). Glycogen branching enzyme (GBE1) mutation causing equine glycogen storage disease IV. Mamm Genome 15:570-577. PMID 15366377.
- Valberg SJ, Ward TL, Rush B, Kinde H, Hiraragi H, Nahey D, Fyfe J, Mickelson JR (2001). Glycogen branching enzyme deficiency in Quarter Horse foals. J Vet Intern Med 15:572-580.
- Ward TL, Valberg SJ, Lear TL, Guerin G, Milenkovic D, Swinburne JE, et al. (2003). Genetic mapping of GBE1 and its association with glycogen storage disease IV in American Quarter horses. Cytogenet Genome Res 102:201-206. doi:10.1159/000075749.
- Wagner ML, Valberg SJ, Ames EG, Bauer MM, Wiseman JA, Penedo MCT, Kinde H, Abbitt B, Mickelson JR (2006). Allele frequency and likely impact of the glycogen branching enzyme deficiency gene in Quarter Horse and Paint Horse populations. J Vet Intern Med 20:1207-1211.
- Tryon RC, Penedo MCT, McCue ME, et al. (2009). Evaluation of allele frequencies of inherited disease genes in subgroups of American Quarter Horses. J Am Vet Med Assoc 234:120-125. doi:10.2460/javma.234.1.120.
- Araujo CET, Delfiol DJZ, Badial PR, Oliveira-Filho JP, Araujo-Junior JP, Borges AS (2018). Prevalence of the glycogen branching enzyme deficiency mutation in Quarter Horses in Brazil. J Equine Vet Sci 62:81-84. doi:10.1016/j.jevs.2017.10.010.
- Brown BN, Hughes S, Le TM, Tatar NP, Grahn JC, Carrillo-Alvarez M, Bellone RR, Finno CJ (2026). Allele frequencies of 7 inherited disorders in performance and random cohorts of American Quarter Horses (2020-2024). J Am Vet Med Assoc 1-7. doi:10.2460/javma.26.04.0256.