A pericentric inversion of chromosome 4 in pigs

The main French porcine artificial insemination centre recently decided to carry out a systematic chromosomal evaluation of the animals used for pure-breeding purposes. This practice has allowed the identification of a new pericentric inversion affecting chromosome 4, in four Large White boars originating from four different herds. The cytogenetic evaluation by means of the GTG-banding technique revealed an inversion of the pericentric part of the chromosome, after double breaks, the first one in the 4q2.3 pale band of the long arm, and the second one in the upper border of the 4p1.4 dark band of the short arm. The chromosomal rearrangement could be described, according to the standard nomenclature, as 38,XY,inv(4) (p14q23). This interpretation has been confirmed by in situ hybridization of the cosmid BHT12 located on the 4p1.5 band. This chromosomal abnormality has no significant effect on production or reproductive performance of carrier animal. A rather old and common origin of the abnormality is hypothesized.