Uzar Tomasz, Szczerbal Izabela, Serwanska-Leja Katarzyna, Nowacka-Woszuk Joanna, Gogulski Maciej, Bugaj Szymon, Switonski Marek, Komosa Marcin
Department of Animal Anatomy, Poznan University of Life Sciences, Wojska Polskiego 71c, 60-625 Poznan, Poland.
Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637 Poznan, Poland.
Animals (Basel). 2020 Sep 10;10(9):1615. doi: 10.3390/ani10091615.
A Holstein-Fresian calf with multiple congenital malformations was subjected postmortem to anatomical and genetic investigation. The calf was small (20 kg), had shortened limbs and was unable to stand up. It lived only 44 days. Detailed anatomical investigation revealed the following features: head asymmetry, the relocation of the frontal sinus and eye orbits, hypoplastic thymus without neck part, ductus Botalli, unfinished obliteration in umbilical arteries, and a bilateral series of tooth germs in the temporal region. Cytogenetic examination, performed on in vitro cultured fibroblasts, showed a unique mosaic karyotype with a marker chromosome-60,XX[9 2%]/60,XX,+mar[8%], which was for the first time described in cattle. No other chromosome abnormalities indicating chromosome instabilities, like chromatid breaks or gaps were identified, thus teratogenic agent exposure during pregnancy was excluded. The marker chromosome (mar) was small and it was not possible to identify its origin, however, sequential DAPI/C (4',6-diamidino-2-phenylindole) band staining revealed a large block of constitutive heterochromatin, which is characteristic for centromeric regions of bovine autosomes. We suppose that the identified marker chromosome was a result of somatic deletion in an autosome and its presence could be responsible for the observed developmental malformations. In spite of the topographic distance among the affected organs, we expected a relationship between anatomical abnormalities. To the of our best knowledge, this is the first case of a mosaic karyotype with a cell line carrying a small marker chromosome described in a malformed calf.
一头患有多种先天性畸形的荷斯坦-弗里生犊牛在死后接受了解剖和基因调查。这头犊牛体型小（20千克），四肢短小，无法站立。它仅存活了44天。详细的解剖调查揭示了以下特征：头部不对称、额窦和眼眶移位、胸腺发育不全且无颈部、动脉导管未闭、脐动脉未完全闭塞以及颞区双侧有一系列牙胚。对体外培养的成纤维细胞进行的细胞遗传学检查显示出一种独特的嵌合核型，即60,XX[92%]/60,XX,+mar[8%]，这在牛中是首次描述。未发现其他表明染色体不稳定的染色体异常，如染色单体断裂或间隙，因此排除了孕期接触致畸剂的可能性。标记染色体（mar）很小，无法确定其来源，然而，连续的DAPI/C（4',6-二脒基-2-苯基吲哚）带染色显示出一大块组成型异染色质，这是牛常染色体着丝粒区域的特征。我们推测所鉴定的标记染色体是常染色体体细胞缺失的结果，其存在可能是观察到的发育畸形的原因。尽管受影响器官之间存在地形距离，但我们预计解剖学异常之间存在关联。据我们所知，这是第一例在畸形犊牛中描述的带有小标记染色体细胞系的嵌合核型病例。
