Complex Vertebral Malformation (CVM)
Complex vertebral malformation (CVM) is a bovine autosomal recessive disorder caused by a single-base mutation of guanine to thymine at nucleotide position 559 of the gene SLC35A3. Bovine SLC35A3 plays a vital role in the development of the axial skeleton. The homozygous mutation is lethal and leads to the abortion of the affected calves before gestation day 260 in approximately 77% of cases. Majority of the calves that survive until the end of the gestation period are stillborn and are phenotypically characterized by retarded growth and mild bilateral flexion of the carpal and pastern joints with rotation of the digits. Additionally, most of the animals have vertebral malformation, malformed ribs, and arthrogryposis of the tarsal and posterior pastern joints. Extensive malformation of the cervical and thoracic vertebrae is observed in typical cases, causing a shortening of the neck. Other malformations have been reported as a part of this syndrome, including cardiac interventricular septal defects, malformation of the great vessels and myocardial hypertrophy.
Fetal mortality causes a decrease in milk production and an increase in the return-to-service rate of cattle, which ultimately leads to the culling of Holstein cattle.
Bulls from several countries are used internationally for the breeding and artificial insemination of Holsteins, respectively, without assessment for the presence of CVM. Therefore, CVM carriers may exist in many countries, and the proportion of carriers in the Holstein population may be increasing silently and rapidly.
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Kotikalapudi, R., Patel, R.K., Sunkara, P.S.S., and Roy, A. (2013). Detection of silent homozygous polymorphism in exon 4 of SLC35A3 gene in a Holstein cattle carrier for complex vertebral malformation. Inter. J. Vet. Sci 2, 61–64.
Wang, S., Hao, H., Zhao, X., Zhu, H., Du, W., Wang, D., Liu, Y., Qin, T., and Wang, Z. (2012). A rapid mismatch polymerase chain reaction assay to detect carriers of complex vertebral malformation in Holstein cattle. J. Vet. Diagn. Invest. 24, 568–571.