DETECCIÓN DE UN DEFECTO GENÉTICO EN BOVINOS MEDIANTE UNA PRUEBA DE ADN. (Detection of a bovine genetic defect by a DNA probe)

The adhesion deficiency of bovine leukocytes to antigens, known as BLAD (bovine leukocyte adhesion deficiency), is a hereditary genetic disease which is lethal for the Holstein breed. It is a recessive autosomal disease that can be transmitted to the offspring. The objective of this research was to standardize the molecular techniques to diagnose BLAD and also to get a first approximation of the genetic frequency of the mutated allele in the bull population of the IX th and X th Regions. DNA amplification using polymerase chain reaction (PCR) and posterior digestion with restriction enzymes Taq I and Hae III was performed. The digested product was analyzed by 4% agarose gel electrophoresis and ethidium bromide staining to show the typical restriction fragments present in normal, carrier and infected cattle. The technique was validated with a screening test of 59 cattle. Out of 55 bulls analyzed, one turned out to be a BLAD carrier, which suggests a genetic frequency of 1.79% in the bull population of the IX th and X th Regions. The diagnostic technique of PCR and the digestion of the amplification product with two restriction enzymes ( Taq I and Hae III) has identified with accuracy the genotype of cattle at a specific locus and allows an early identification of the genetic defect known as BLAD in infected and carrier animals