Novel Complex Unbalanced Dicentric X-Autosome Rearrangement in a Thoroughbred Mare with a Mild Effect on the Phenotype

• Autores: Mendoza, M. N., Schalnus, S. A., Thomson, B., Bellone, R. R., Juras, R., Raudsepp, T.
• Formato: artículo
• Fecha de Publicación: 2020
• Institución: Instituto Nacional de Innovación Agraria
• Repositorio: INIA-Institucional
• Lenguaje: inglés
• OAI Identifier: oai:null:20.500.12955/1410
• Enlace del recurso: https://hdl.handle.net/20.500.12955/1410; https://doi.org/10.1159/000511236
• Nivel de acceso: acceso abierto
• Materia: Complex rearrangement; Dicentric; Horse; Unbalanced; X-autosome translocation; https://purl.org/pe-repo/ocde/ford#4.04.02

Complex structural X chromosome abnormalities are rare in humans and animals, and not recurrent. Yet, each case provides a fascinating opportunity to evaluate X chromosome content and functional status in relation to the effect on the phenotype. Here, we report the first equine case of a complex unbalanced X-autosome rearrangement in a healthy but short in stature Thoroughbred mare. Studies of about 200 cells by chromosome banding and FISH revealed an abnormal 2n=63,X,der(X;16) karyotype with a large dicentric derivative chromosome (der). The der was comprised of normal Xp material, a palindromic duplication of Xq12q21, and a translocation of chromosome 16 to the inverted Xq12q21 segment by the centromere, whereas the distal Xq22q29 was deleted from the der. Microsatellite genotyping determined a paternal origin of the der. While there was no option to experimentally investigate the status of X chromosome inactivation (XCI), the observed mild phenotype of this case suggested the following scenario to retain an almost normal genetic balance: active normal X, inactivated X-portion of the der, but without XCI spreading into the translocated chromosome 16. Cases like this present unique resources to acquire information about species-specific features of X regulation and the role of X-linked genes in development, health, and disease.