OMIA:000576-9823 : Knobbed acrosome in Sus scrofa (pig)

In other species: dog , horse , taurine cattle , sheep

Categories: Reproductive system phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 606165 (gene)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal recessive

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2020

Cross-species summary: The presence of a protrusion (knob) on the acrosome (cap) of a sperm. Associated with sterility. Also known as Knobbed Acrosome Defect (KAD)

Inheritance: This disorder is certainly familial, but the limited evidence for single-gene inheritance is not convincing.

Mapping: Sironen et al. (2010): "A genome wide scan with PorcineSNP60 Genotyping BeadChip defined the KAD associated region within 0.7 Mbp on porcine chromosome 15." Nosková et al. (2020) mapped the disorder to a "12.24 Mb segment of extended homozygosity".

Molecular basis: Nosková et al. (2020) "sequenced the genomes of two affected and three unaffected boars to an average coverage of 11‐fold. Read depth analysis revealed a 55 kb deletion that is associated with the acrosome defect. The deletion encompasses the BOLL gene encoding the boule homolog, an RNA binding protein which is an evolutionarily conserved member of the DAZ (Deleted in AZoospermia) gene family. Lack of BOLL expression causes spermatogenic arrest and sperm maturation failure in many species. Boars that carry the deletion in the homozygous state produce sperm but their acrosomes are defective, suggesting that lack of porcine BOLL compromises acrosome formation."

Associated gene:

Symbol Description Species Chr Location OMIA gene details page Other Links
BOLL boule-like RNA-binding protein Sus scrofa 15 NC_010457.5 (101602232..101535392) BOLL Homologene, Ensembl , NCBI gene


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WARNING! Inclusion of a variant in this table does not automatically mean that it should be used for DNA testing. Anyone contemplating the use of any of these variants for DNA testing should examine critically the relevant evidence (especially in breeds other than the breed in which the variant was first described). If it is decided to proceed, the location and orientation of the variant sequence should be checked very carefully.

Since October 2021, OMIA includes a semiautomated lift-over pipeline to facilitate updates of genomic positions to a recent reference genome position. These changes to genomic positions are not always reflected in the ‘acknowledgements’ or ‘verbal description’ fields in this table.

OMIA Variant ID Breed(s) Variant Phenotype Gene Allele Type of Variant Source of Genetic Variant Reference Sequence Chr. g. or m. c. or n. p. Verbal Description EVA ID Year Published PubMed ID(s) Acknowledgements
1254 Yorkshire (Pig) Knobbed acrosome defect BOLL deletion, gross (>20) Naturally occurring variant Sscrofa11.1 15 g.101549770_101604750del 2020 32975846

Cite this entry

Nicholas, F. W., Tammen, I., & Sydney Informatics Hub. (2020). OMIA:000576-9823: Online Mendelian Inheritance in Animals (OMIA) [dataset].


Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.

2020 Nosková, A., Wurmser, C., Crysnanto, D., Sironen, A., Uimari, P., Fries, R., Andersson, M., Pausch, H. :
Deletion of porcine BOLL is associated with defective acrosomes and subfertility in Yorkshire boars. Anim Genet , 2020. Pubmed reference: 32975846. DOI: 10.1111/age.12998.
2010 Sironen, A., Uimari, P., Nagy, S., Paku, S., Andersson, M., Vilkki, J. :
Knobbed acrosome defect is associated with a region containing the genes STK17b and HECW2 on porcine chromosome 15. BMC Genomics 11:699, 2010. Pubmed reference: 21143916. DOI: 10.1186/1471-2164-11-699.
2008 Kopp, C., Sironen, A., Ijäs, R., Taponen, J., Vilkki, J., Sukura, A., Andersson, M. :
Infertile boars with knobbed and immotile short-tail sperm defects in the Finnish Yorkshire breed. Reprod Domest Anim 43:690-5, 2008. Pubmed reference: 18397189. DOI: 10.1111/j.1439-0531.2007.00971.x.
1993 Toyama, Y., Itoh, Y. :
Ultrastructural Features and Pathogenesis of Knobbed Spermatozoa in a Boar American Journal of Veterinary Research 54:743-749, 1993. Pubmed reference: 8317767.
1988 Revell, SG., Chasey, D. :
Morphological defects of the acrosome in boar spermatozoa. Res Vet Sci 45:149-51, 1988. Pubmed reference: 3194583.
1985 Alanko, M. :
[Inherited acrosome defects of boar spermatozoa and their effect on ova fertilization in the sow] Tierarztliche Umschau 40:564-566, 1985.
1984 Alanko, M. :
The knobbed sperm defect in boars: fertility and inheritance of the defect :3 pp., 1984.
1982 Ollivier, L., Sellier, P. :
Pig genetics: a review Annales de Genetique et de Selection Animale 14:481-544, 1982.
1972 Bishop, M.W.H. :
Genetically determined abnormalities of the reproductive system Journal of Reproduction and Fertility 15 suppl:51-78, 1972.
1968 Bane, A., Nicander, L. :
Electron and light microscopical studies in spermateliosis in a boar with acrosomal abnormalities Journal of Reproduction and Fertility 11:133-138, 1968.
1965 Buttle, H.R.L., Hancock, J.L. :
Sterile boars with knobbed spermatozoa Journal of Agricultural Science 65:255-260, 1965.
1961 Wohlfarth, E. :
Beitrag zum Akrosom-Defekt im Ebersperma [Acrosome defect of boar spermatozoa] Zuchthygiene, Fortpflanzungsstorungen und Besamung der Haustiere 5:268-274, 1961.

Edit History

  • Created by Frank Nicholas on 06 Sep 2005
  • Changed by Frank Nicholas on 26 Oct 2020