Valera Mercedes, Karlau Ayelén, Anaya Gabriel, Bugno-Poniewierska Monika, Molina Antonio, Encina Ana, Azor Pedro J, Demyda-Peyrás Sebastián
Departamento de Agronomía, Escuela Técnica Superior de Ingeniería Agronómica, Ctra. Utrera km 1, Universidad de Sevilla, 41013 Sevilla, Spain.
CONICET-Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, Calle 60 y 118 s/n, La Plata 1900, Argentina.
Animals (Basel). 2024 Sep 3;14(17):2560. doi: 10.3390/ani14172560.
Sex chromosomal abnormalities are a well-established cause of reproductive failure in domestic horses. Because of its difficult diagnosis, the Pura Raza Español breeding program established a routine screening for chromosomal abnormalities in all the horses prior to enrolling in the studbook. This genomic procedure combines an initial assessment based on the results from Short Tandem Repeat (STR) parentage testing followed by a Single-Nucleotide Polymorphism (SNP) based copy number aberration (CNA) confirmative analysis in positive cases. Using this methodology, we identified five new individuals carrying a 65,XXY chromosomal number aberration (CNA) among 27,330 foals enrolled over the past two reproductive seasons. The animals were initially flagged as CNA candidates due to abnormal results in STR testing. Subsequent analysis genotyping using an STR sex-linked dedicated panel and a medium-density SNP array in ECAX and ECAY confirmed the diagnosis as 65,XXY carriers. Four cases (upon sample availability) underwent further analysis using in situ fluorescent hybridization with ECAX and ECAY probes, showing identical results. Phenotypic analysis revealed abnormal gonad development in one of the cases, showing that the remaining four had a normal reproductive morphology. To our knowledge, this represents the largest number of horses exhibiting the equine form of Klinefelter syndrome (65,XXY) reported to date. Our study highlights the importance of genomic screening in the accurate detection of chromosomal abnormalities in horses.
性染色体异常是家马繁殖失败的一个公认原因。由于诊断困难，西班牙纯种马繁育计划在所有马匹登记入种马登记簿之前，对染色体异常进行常规筛查。这种基因组检测方法首先基于短串联重复序列（STR）亲子鉴定结果进行初步评估，然后对阳性病例进行基于单核苷酸多态性（SNP）的拷贝数变异（CNA）确认分析。使用这种方法，在过去两个繁殖季节登记的27330匹驹中，我们鉴定出5匹携带65,XXY染色体数变异（CNA）的新个体。这些动物最初因STR检测结果异常而被标记为CNA候选者。随后使用STR性连锁专用面板以及ECA X和ECA Y中的中密度SNP阵列进行基因分型分析，证实诊断为65,XXY携带者。4例（样本可用）使用ECA X和ECA Y探针进行荧光原位杂交进一步分析，结果相同。表型分析显示其中1例性腺发育异常，其余4例生殖形态正常。据我们所知，这是迄今为止报道的表现出马的克兰费尔特综合征（65,XXY）形式的马匹数量最多的一次。我们的研究强调了基因组筛查在准确检测马染色体异常中的重要性。
