Constitutional trisomy 20 in an aborted Holstein fetus with pulmonary hypoplasia and anasarca syndrome

Parma

2021

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.

Section: Autosomesmentioning

confidence: 98%

Chromosome Abnormalities and Fertility in Domestic Bovids: A Review

Parma

2021

Molecular Cytogenetics in Domestic Bovids: A Review

Parma

2023

The discovery of the Robertsonian translocation (rob) involving cattle chromosomes 1 and 29 and the demonstration of its deleterious effects on fertility focused the interest of many scientific groups on using chromosome banding techniques to reveal chromosome abnormalities and verify their effects on fertility in domestic animals. At the same time, comparative banding studies among various species of domestic or wild animals were found useful for delineating chromosome evolution among species. The advent of molecular cytogenetics, particularly the use of fluorescence in situ hybridization (FISH), has allowed a deeper investigation of the chromosomes of domestic animals through: (a) the physical mapping of specific DNA sequences on chromosome regions; (b) the use of specific chromosome markers for the identification of the chromosomes or chromosome regions involved in chromosome abnormalities, especially when poor banding patterns are produced; (c) better anchoring of radiation hybrid and genetic maps to specific chromosome regions; (d) better comparisons of related and unrelated species by comparative FISH mapping and/or Zoo-FISH techniques; (e) the study of meiotic segregation, especially by sperm-FISH, in some chromosome abnormalities; (f) better demonstration of conserved or lost DNA sequences in chromosome abnormalities; (g) the use of informatic and genomic reconstructions, in addition to CGH arrays, to predict conserved or lost chromosome regions in related species; and (h) the study of some chromosome abnormalities and genomic stability using PCR applications. This review summarizes the most important applications of molecular cytogenetics in domestic bovids, with an emphasis on FISH mapping applications.

A Splice Site Variant in ADAMTS3 Is the Likely Causal Variant for Pulmonary Hypoplasia with Anasarca in Persian/Persian-Cross Sheep

Woolley,

Hopkins,

Khatkar

et al. 2024

Pulmonary hypoplasia with anasarca, or hydrops fetalis, is characterized by stillbirth, diffuse oedema, and generalized lymph node hypoplasia. The enlarged fetus frequently causes dystocia. The disease has been reported in cattle and sheep as an inherited condition with a recessive mode of inheritance. This is the first report of the disease in Persian/Persian-cross sheep in Australia. Affected fetuses were reported from three flocks, and a total of eleven affected, eleven obligate carrier, and 188 related Persian/Persian-cross animals were available for analysis, as well as unrelated control animals. SNP genotyping revealed a region of homozygosity in affected animals on ovine chromosome six, which contained the functional candidate gene ADAMTS3. Whole genome sequencing of two affected fetuses and one obligate carrier ewe revealed a single nucleotide deletion, ENSOARG00000013204:g.87124344delC, located 3 bp downstream from a donor splice site region in the ADAMTS3 gene. Sanger sequencing of cDNA containing this variant further revealed that it is likely to introduce an early splice site in exon 14, resulting in a loss of 6 amino acids at the junction of exon 14 and intron 14/15. A genotyping assay was developed, and the ENSOARG00000013204:g.87124344delC segregated with disease in 209 animals, allowing for effective identification of carrier animals.