{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T10:25:23Z","timestamp":1787135123402,"version":"build-2736575974"},"reference-count":30,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T00:00:00Z","timestamp":1787097600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Genes"],"abstract":"<jats:p>Background\/Objectives: The fibroblast-growth-factor 4 retrogene insertion on chromosome 12 (FGF4L2) is known to be associated with chondrodystrophy and intervertebral disc disease (IVDD), which increases the risk of Hansen\u2019s type I intervertebral disc extrusion (IVDE) in Dachshunds. While the FGF4L2 insertion is known to occur at high frequency within the breed, subgroup-specific data relating to coat-type and size categories remain limited. This pilot study aimed to determine the distribution of FGF4L2 and wild-type (N) alleles in a cohort of Dachshunds registered with the German Dachshund Club (DTK) and to evaluate differences among coat and size varieties. Methods: A total of 488 Dachshund samples from the DNA archive of the Deutscher Teckelklub 1888 e.V. (DTK) were analysed and genotyped. Genotype data was categorised according to coat-type and size variant. Allele and genotype frequencies were calculated for the overall population and for each subgroup. Results: The overall frequency of the FGF4L2 insertion allele was 96.51% (95% CI: 95.17\u201397.50). However, there were moderate differences between subgroups. The allele was nearly fixed in several coat and size variants. Standard wire-haired Dachshunds had the lowest allele frequency (89.09%) and were the only group in which homozygous wild-type individuals were observed. Heterozygous frequencies peaked in standard smooth-haired (16.7%) and standard wire-haired (14.5%) groups. Conclusions: Because the FGF4L2 frequency differs meaningfully between Dachshund varieties, grouping them into a single breed, as many studies do, can obscure the residual subgroup-specific genetic variation present in this population. Analysing the varieties separately provides a basis for future studies investigating factors that may interact with FGF4L2 in IVDE, thereby highlighting its multifactorial nature. It also reveals where wild-type alleles persist, making genotype-informed, variety-specific breeding a viable strategy for improving vertebral column health. However, variation in FGF4L2 allele frequency alone may not fully account for the recently reported differences in vertebral column health between Dachshund coat varieties.<\/jats:p>","DOI":"10.3390\/genes17080969","type":"journal-article","created":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T09:30:53Z","timestamp":1787131853000},"page":"969","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Genotypic Distribution of FGF4L2 in DTK-Registered Dachshunds in Germany: A Pilot Study"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-2255-2960","authenticated-orcid":false,"given":"Hanna","family":"Berls","sequence":"first","affiliation":[{"name":"Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, 30559 Hannover, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan Peter","family":"Bach","sequence":"additional","affiliation":[{"name":"German Kennel Club (Verband f\u00fcr das Deutsche Hundewesen, VDH) e.V., 44141 Dortmund, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7614-7207","authenticated-orcid":false,"given":"Danika","family":"Bannasch","sequence":"additional","affiliation":[{"name":"Department of Population Health and Reproduction, University of California-Davis, Davis, CA 95616, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0037-2619","authenticated-orcid":false,"given":"Peter J.","family":"Dickinson","sequence":"additional","affiliation":[{"name":"Department of Surgical and Radiological Sciences, University of California-Davis, Davis, CA 95616, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7312-638X","authenticated-orcid":false,"given":"Holger A.","family":"Volk","sequence":"additional","affiliation":[{"name":"Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover, 30559 Hannover, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.3109\/ort.1952.23.suppl-11.01","article-title":"A pathologic-anatomical study on disc degeneration in dog, with special reference to the so-called enchondrosis intervertebralis","volume":"23","author":"Hansen","year":"1952","journal-title":"Acta Orthop. Scand. Suppl."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e81","DOI":"10.1136\/vr.105844","article-title":"Intervertebral disc disease and aortic thromboembolism are the most common causes of acute paralysis in dogs and cats presenting to an emergency clinic","volume":"187","author":"Rossi","year":"2020","journal-title":"Vet. Rec."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1111\/jsap.12496","article-title":"Practice patterns in the management of acute intervertebral disc herniation in dogs","volume":"57","author":"Moore","year":"2016","journal-title":"J. Small Anim. Pract."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1570","DOI":"10.1111\/jvim.16480","article-title":"ACVIM consensus statement on diagnosis and management of acute canine thoracolumbar intervertebral disc extrusion","volume":"36","author":"Olby","year":"2022","journal-title":"J. Vet. Intern. Med."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1300","DOI":"10.2460\/javma.240.11.1300","article-title":"Incidence of intervertebral disk degeneration-related diseases and associated mortality rates in dogs","volume":"240","author":"Bergknut","year":"2012","journal-title":"J. Am. Vet. Med. Assoc."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Packer, R.M., Hendricks, A., Volk, H.A., Shihab, N.K., and Burn, C.C. (2013). How long and low can you go? Effect of conformation on the risk of thoracolumbar intervertebral disc extrusion in domestic dogs. PLoS ONE, 8.","DOI":"10.1371\/journal.pone.0069650"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1186\/s40575-016-0039-8","article-title":"DachsLife 2015: An investigation of lifestyle associations with the risk of intervertebral disc disease in Dachshunds","volume":"3","author":"Packer","year":"2016","journal-title":"Canine Genet. Epidemiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1186\/BF03548090","article-title":"Calcification of intervertebral discs in the dachshund: A radiographic study of 115 dogs at 1 and 5 years of age","volume":"37","author":"Stigen","year":"1996","journal-title":"Acta Vet. Scand."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e17281","DOI":"10.1111\/jvim.17281","article-title":"The relationship between radiographic disc calcification score and FGF4L2 genotype in dachshunds","volume":"39","author":"Sullivan","year":"2025","journal-title":"J. Vet. Intern. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"11476","DOI":"10.1073\/pnas.1709082114","article-title":"FGF4 retrogene on CFA12 is responsible for chondrodystrophy and intervertebral disc disease in dogs","volume":"114","author":"Brown","year":"2017","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Batcher, K., Dickinson, P., Giuffrida, M., Sturges, B., Vernau, K., Knipe, M., Rasouliha, S.H., Drogemuller, C., Leeb, T., and Maciejczyk, K. (2019). Phenotypic Effects of FGF4 Retrogenes on Intervertebral Disc Disease in Dogs. Genes, 10.","DOI":"10.3390\/genes10060435"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1002\/wdev.176","article-title":"The Fibroblast Growth Factor signaling pathway","volume":"4","author":"Ornitz","year":"2015","journal-title":"Wiley Interdiscip. Rev. Dev. Biol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"755","DOI":"10.1242\/dev.114.3.755","article-title":"Fgf-4 expression during gastrulation, myogenesis, limb and tooth development in the mouse","volume":"114","author":"Niswander","year":"1992","journal-title":"Development"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"501","DOI":"10.1038\/nature00902","article-title":"Functions of FGF signalling from the apical ectodermal ridge in limb development","volume":"418","author":"Sun","year":"2002","journal-title":"Nature"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"103","DOI":"10.4172\/2168-9296.1000103","article-title":"Bridging the Gap: Understanding Embryonic Interverterbal Disc Development","volume":"1","author":"V","year":"2012","journal-title":"Cell Dev. Biol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"995","DOI":"10.1126\/science.1173275","article-title":"An expressed fgf4 retrogene is associated with breed-defining chondrodysplasia in domestic dogs","volume":"325","author":"Parker","year":"2009","journal-title":"Science"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Dickinson, P.J., and Bannasch, D.L. (2020). Current Understanding of the Genetics of Intervertebral Disc Degeneration. Front. Vet. Sci., 7.","DOI":"10.3389\/fvets.2020.00431"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Kubiak, M.R., and Makalowska, I. (2017). Protein-Coding Genes\u2019 Retrocopies and Their Functions. Viruses, 9.","DOI":"10.3390\/v9040080"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Bannasch, D., Batcher, K., Leuthard, F., Bannasch, M., Hug, P., Marcellin-Little, D.J., Dickinson, P.J., Drogemuller, M., Drogemuller, C., and Leeb, T. (2022). The Effects of FGF4 Retrogenes on Canine Morphology. Genes, 13.","DOI":"10.3390\/genes13020325"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Donner, J., Freyer, J., Davison, S., Anderson, H., Blades, M., Honkanen, L., Inman, L., Brookhart-Knox, C.A., Louviere, A., and Forman, O.P. (2023). Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs. PLoS Genet., 19.","DOI":"10.1371\/journal.pgen.1010651"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"aalag153","DOI":"10.1093\/jvimsj\/aalag153","article-title":"Dachshund spinal health by coat and size type","volume":"40","author":"Hopper","year":"2026","journal-title":"J. Vet. Intern. Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"258","DOI":"10.1111\/jvim.16925","article-title":"Association of the FGF4L2 retrogene with fibrocartilaginous embolic myelopathy in dogs","volume":"38","author":"Embersics","year":"2023","journal-title":"J. Vet. Intern. Med."},{"key":"ref_23","unstructured":"R Core Team (2026). R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing."},{"key":"ref_24","unstructured":"(2022). Dachshund (Teckel) (Standard No. FCI Standard No. 148)."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1186\/s40575-020-00085-9","article-title":"Variation in breeding practices and geographic isolation drive subpopulation differentiation, contributing to the loss of genetic diversity within dog breed lineages","volume":"7","author":"Lampi","year":"2020","journal-title":"Canine Med. Genet."},{"key":"ref_26","unstructured":"University of California (2026, July 23). Chondrodystrophy (CDDY and IVDD) and Chondrodysplasia (CDPA). Available online: https:\/\/vgl.ucdavis.edu\/test\/cddy-cdpa."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1186\/s40575-020-00096-6","article-title":"Breeding schemes for intervertebral disc disease in dachshunds: Is disc calcification score preferable to genotyping of the FGF4 retrogene insertion on CFA12?","volume":"7","author":"Bruun","year":"2020","journal-title":"Canine Med. Genet."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1","DOI":"10.2460\/ajvr.22.09.0167","article-title":"FGF4L2 retrogene copy number is associated with intervertebral disc calcification and vertebral geometry in Nova Scotia Duck Tolling Retrievers","volume":"84","author":"Bianchi","year":"2023","journal-title":"Am. J. Vet. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1090","DOI":"10.2460\/javma.233.7.1090","article-title":"Quantification of the association between intervertebral disk calcification and disk herniation in Dachshunds","volume":"233","author":"Jensen","year":"2008","journal-title":"J. Am. Vet. Med. Assoc."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1186\/s13028-014-0089-4","article-title":"Intervertebral disc disease in Dachshunds radiographically screened for intervertebral disc calcifications","volume":"56","author":"Lappalainen","year":"2014","journal-title":"Acta Vet. Scand."}],"container-title":["Genes"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4425\/17\/8\/969\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,19]],"date-time":"2026-08-19T09:39:09Z","timestamp":1787132349000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4425\/17\/8\/969"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,19]]},"references-count":30,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["genes17080969"],"URL":"https:\/\/doi.org\/10.3390\/genes17080969","relation":{},"ISSN":["2073-4425"],"issn-type":[{"value":"2073-4425","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,19]]}}}