Chromosome Abnormalities and Fertility in Domestic Bovids: A Review

Abstract

After discovering the Robertsonian translocation rob(1;29) in Swedish red cattle and demonstrating its harmful effect on fertility, the cytogenetics applied to domestic animals have been widely expanded in many laboratories in order to find relationships between chromosome abnormalities and their phenotypic effects on animal production. Numerical abnormalities involving autosomes have been rarely reported, as they present abnormal animal phenotypes quickly eliminated by breeders. In contrast, numerical sex chromosome abnormalities and structural chromosome anomalies have been more frequently detected in domestic bovids because they are often not phenotypically visible to breeders. For this reason, these chromosome abnormalities, without a cytogenetic control, escape selection, with subsequent harmful effects on fertility, especially in female carriers. Chromosome abnormalities can also be easily spread through the offspring, especially when using artificial insemination. The advent of chromosome banding and FISH-mapping techniques with specific molecular markers (or chromosome-painting probes) has led to the development of powerful tools for cytogeneticists in their daily work. With these tools, they can identify the chromosomes involved in abnormalities, even when the banding pattern resolution is low (as has been the case in many published papers, especially in the past). Indeed, clinical cytogenetics remains an essential step in the genetic improvement of livestock.

Chromosomal Aberrations in Cattle

“…In addition to translocations 1 and 29, which are monocentric, there are many other types of dicentric Robertson translocations, as reviewed in [18,23] [41] in Holstein cattle-cows with Repeat Breeder Syndrome usually connected with the infertility problem (Table 1). A finding of a new dicentric Robertsonian translocation rob(3;16) in a bull from the Montbéliarde dairy cattle breed with a significant interchromosomal effect (ICE) for two different autosomes, BTA17 and BTA20, was recently published [38].…”

“…Similarly, trisomy of chromosome 18 associated with extreme brachygnathia (lethal brachygnathia trisomy syndrome, LBTS) has been reported in calves that died soon after birth [ 21 ]. Trisomies of several other smaller chromosomes, such as 12, 16, 17, 20, 22, 23, 24 [ 21 ], and chromosome 29 [ 22 ], have been detected in cattle with severe anatomical abnormalities mostly resulting in early death (recently overviewed in Iannuzzi et al [ 23 ]). In 2015, partial trisomy 25q and partial monosomy 11q (60, XX) were detected in a newborn calf of Agerolese cattle who died after two weeks.…”

“…They have a milder effect on viability but a negative impact on fertility [ 25 , 26 , 27 ]. Sex chromosome abnormalities, such as X trisomy and X monosomy, XXY syndrome, sex reversal syndromes (XY; XX), and chimerism XX/XY, are described in the latest work of Iannuzzi et al [ 23 ]. The last-mentioned syndrome is the most common sex chromosome abnormality observed in bovine twins of different sexes, connected with reduced fertility of females and to a lesser extent in males.…”

“…In addition to translocations 1 and 29, which are monocentric, there are many other types of dicentric Robertson translocations, as reviewed in [ 18 , 23 ]. Rob(1;21), rob(23;26), rob(24;26), and rob(26;29) were reported by Arslan et al [ 41 ] in Holstein cattle—cows with Repeat Breeder Syndrome usually connected with the infertility problem ( Table 1 ).…”

“…This could be caused by the inability of conventional Giemsa staining to visualize the rcps, by the absence of abnormal phenotype in carriers, or by the early death of embryos carrying rcp that contains genes with relevant functions in foetal development [ 47 ]. Approximately 20 reciprocal translocations have been described in cattle so far (overviewed in [ 18 , 23 , 24 , 48 ]). Recently, the study of Iannuzzi et al [ 23 ] provided a comprehensive review of reciprocal translocations found to date in cattle, with the chromosomes involved and phenotype effects.…”