OMIA 002134-9913 : Abortion due to haplotype AH2 in Bos taurus

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Recessive

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2017

History: Details of the first Ayrshire lethal haplotype (AH1) are presented in OMIA 001934-9913. Null et al. (2017) reported that "A second [Ayrshire] haplotype [AH2] reached the threshold for statistical significance (7 expected homozygotes and none observed) in October 2013. Sire conception rate was 6.1% lower for matings of carrier sires to cows with carrier maternal grandsires, but the effect was not significant. As of December 2016, 23.5 homozygotes were expected but none had been observed."

Molecular basis: Null et al. (2017): "A splice acceptor variant at 51,267,548 bp in the RNA Polymerase 2 Associated Protein (RPAP2) gene was the most likely causal variant in the [AH2] haplotype. RPAP2 is an essential component of the RNA polymerase 2 holoenzyme necessary for transcription of snRNA species. Experiments with mouse knockouts also found a deficiency of homozygotes, suggesting that RPAP2 is necessary for embryonic development."

Prevalence: Null et al. (2017) reported that the frequency of the AH2 haplotype "has increased from 6% in animals born in 1990 to 21.7% for animals born since 2008."

Breed: Ayrshire.

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
RPAP2 RNA polymerase II associated protein 2 Bos taurus 3 NC_037330.1 (51122541..50994696) RPAP2 Homologene, Ensembl, NCBI gene


By default, variants are sorted chronologically by year of publication, to provide a historical perspective.

Readers can re-sort on any column by clicking on the column header. Click it again to sort in a descending order. To create a multiple-field sort, hold down Shift while clicking on the required column headers

Breed(s) Variant Phenotype Gene Allele Type of Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Year Published PubMed ID(s) Acknowledgements
Ayrshire Abortion due to haplotype AH2 RPAP2 splicing 3 g.51267548 2017 Reference not in PubMed; see OMIA 002134-9913 for reference details


2017 Null, D.J., Hutchison, J.L., Bickhart, D.M., VanRaden, P.M., Cole, J.B. :
Discovery of a haplotype affecting fertility in Ayrshire dairy cattle and identification of a putative causal variant. J. Dairy Sci. 100 (Suppl. 2):199 (Abstract 206), 2017.

Edit History

  • Created by Frank Nicholas on 22 Nov 2017