👤 F R Seefried

In the Swiss Fleckvieh (SF) cattle breed, derived from crosses between the Holstein (HO) and Simmental (SI) breeds, two inherited diseases, thrombocytopathy (TP) and bovine dilated cardiomyopathy (BDCMP), and four so-called fertility haplotypes, Fleckvieh haplotype 1,2,4,5 (FH1,2,4,5), have been described so far. In addition, the APOB-related hereditary disease cholesterol deficiency (CD) has been thoroughly described in the closely related HO breed after its discovery in 2015, but to date it has not been reported in the SF breed. The hereditary disease retinitis pigmentosa (RP), which leads to progressive retinal degeneration in homozygous carriers of a pathogenic variant of the RP1 gene, has been shown to occur in several European cattle breeds, but has not been described in the SF population. The aim of this study was to determine the prevalence of the known genetic defects and fertility haplotypes, as well as CD, in SF and the two closely related breeds, HO and SI. We also investigated the prevalence of RP in the SF population and characterised the genetic disease through a case series. To determine the prevalence, the SNP array genotyping data of over 65 000 cattle from the Swiss breeding association database were analyzed and based on those results, four RP1 homozygous animals were clinically evaluated. The allele frequency of the RP causing allele in SF was 13 % and the CD causing allele, previously described only in HO, was found in SF with an allele frequency of 1,17 %. The remaining six genetic defects occurred in SF either with a low allele frequency (TP 0,24 %, BDCMP 1,93 %, FH2 0,03 %, FH5 0,02 %) or not at all (FH1, FH4). The four RP1 homozygous animals with a mean age of 7,5 years old Showed varying degrees of visual impairment. Overall, the clinical and pathological findings were consistent with RP1-associated RP. In a suspected case, RP1 genotyping by genetic testing can confirm the diagnosis of RP. Due to the routine use of SNP genotyping to estimate breeding values, the genotypes of genetic defects are known, at least in the active breeding population, and can therefore be considered before matings. Avoiding risk mating will improve animal health and welfare and prevent animal losses, and therefore economic losses. Show less

Recently, a new hereditary disease, bovine lymphocyte intestinal retention defect (BLIRD), was discovered in Holstein cattle in France and is caused by a variant in the Integrin subunit beta 7 (ITGB7) gene. The altered cell adhesion molecule resulting from this point mutation is responsible for an impaired tissue of CD4 T lymphocytes from the blood to intestinal tissue. The aim of this study was to assess the allelic frequency of this deleterious variant in the local Holstein population and to clinically examine ten BLIRD-affected Holstein cattle from Switzerland in order to characterise the phenotype of this new hereditary disease, which is still unknown to the veterinary community. BLIRD was associated with severely impaired animal health in the rearing phase and significantly reduced animal welfare due to weakened immune defences, below-average development and recurrent diarrhoea. Further examinations revealed increased leucocyte values and a slightly increased average age at first calving. Affected homozygous animals are labelled internationally as BLIRD-carrier homozygous (LRS), BLIRD-carrier heterozygous (LRC) and BLIRD-free (LRF). An obvious inbreeding practice was clearly demonstrated by the pedigree analysis of the ten animals, which all trace back to the potential founder bull. Herein, BLIRD has been detected and described in Switzerland for the first time. The ITGB7 variant allele has a frequency of 2,1 % in the current Swiss Holstein population, which is below the level of the cholesterol deficiency (CD)-associated apolipoprotein B (APOB) variant allele with a frequency of 3,9 %. Although relatively rare, attention should be paid to the BLIRD genotype when mating in order to exclude further affected animals. In cattle with clinically suspected BLIRD, the diagnosis should be confirmed by genetic testing. Show less