OMIA 001544-9913 : Hypotrichosis with coat-colour dilution (rat-tail syndrome) in Bos taurus

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal Dominant

Considered a defect: yes

Key variant known: no

Species-specific name: rat-tail syndrome

Species-specific symbol: RTS

Species-specific description: Knaust et al. (2016) reported: "evidence that the RTS phenotype results from an epistatic interaction between three independent loci: dilution (that corresponds to the PMEL gene at 55 Mb on BTA5), extension (that corresponds to the MC1R gene on BTA18) and the RTS locus that is located in the interval between 14 and 22 Mb on BTA5. The prerequisites for expression of the RTS phenotype are a eumelanic background due to the presence of the dominant ED allele at MC1R (extension locus) and a heterozygous genotype at the PMEL gene variant c.64G>A (dilution locus). The positions of the RTS and dilution loci on BTA5 are clearly distinct."

Mapping: Knaust et al. (2016) mapped RTS to a region of chromosome BTA5 "between 14 and 22 Mb ".

Molecular basis: Jolly et al. (2008) summarised the results in an unpublished thesis by Hecht (2006) as: "In a genetic study of an experimental Simmental crossbred herd, the coat-colour dilution/hypotrichosis phenotype segregated with a three-base (CTT) deletion at nucleotide 54 in exon 1 of the PMel17 gene (Hecht 2006). Although the study was not conclusive, this is the presumptive mutation for the disorder. A second single nucleotide polymorphism, a C→A transition in exon 11 in the second nucleotide of codon 612 of the same PMel17 gene, segregated with most, but not all, animals with the same phenotype."

Reporting their investigation of the same disorder in Hereford-cross cattle, Jolly et al. (2008) identified the same two mutations: "a three-base deletion (CTT) at nucleotide 54" in exon 1 and "a single missence [sic] mutation in one copy of this exon, resulting in a C→A substitution in codon 612" in exon 11.

However, as reported by Knaust et al. (2016), in two papers published in 2007 (both listed below), Kühn and Weikard "showed that neither mutations in the coding and regulatory regions of the PMEL gene, nor splicing variants of this gene are associated with RTS". Knaust et al. (2016) went on to report that RTS in a German Holstein x Charolais population is due to the interaction of three loci: "In this population, the RTS is exclusively expressed in animals with a eumelanic background that is due to the dominant ED allele at the melanocortin 1 receptor gene located on Bos taurus autosome (BTA) 18. In addition, only the individuals that are heterozygous at the dilution locus on BTA5 that corresponds to the premelanosome protein or silver gene variant c.64G>A were classified as displaying a RTS phenotype. Linkage and whole-genome association analyses using different models and different pedigrees allowed us to map a third locus (hereafter referred to as the RTS locus) that is essential for the expression of the RTS phenotype to the chromosomal region between 14 and 22 Mb on BTA5. Our findings clearly demonstrate that the RTS and dilution loci are distinct loci on BTA5".

Associated genes:

Symbol Description Species Chr Location OMIA gene details page Other Links
MC1R melanocortin 1 receptor (alpha melanocyte stimulating hormone receptor) Bos taurus 18 NC_037345.1 (14705093..14706843) MC1R Homologene, Ensembl, NCBI gene
PMEL premelanosome protein Bos taurus 5 NC_037332.1 (57344579..57353378) PMEL Homologene, Ensembl, NCBI gene


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.
2016 Knaust, J., Hadlich, F., Weikard, R., Kuehn, C. :
Epistatic interactions between at least three loci determine the "rat-tail" phenotype in cattle. Genet Sel Evol 48:26, 2016. Pubmed reference: 27037038. DOI: 10.1186/s12711-016-0199-8.
2008 Jolly, RD., Wills, JL., Kenny, JE., Cahill, JI., Howe, L. :
Coat-colour dilution and hypotrichosis in Hereford crossbred calves. N Z Vet J 56:74-7, 2008. Pubmed reference: 18408794. DOI: 10.1080/00480169.2008.36812.
2007 Kuehn, C., Weikard, R. :
Multiple splice variants within the bovine silver homologue (SILV) gene affecting coat color in cattle indicate a function additional to fibril formation in melanophores. BMC Genomics 8:335, 2007. Pubmed reference: 17892572. DOI: 10.1186/1471-2164-8-335.
Kühn, C.h., Weikard, R. :
An investigation into the genetic background of coat colour dilution in a Charolais x German Holstein F2 resource population. Anim Genet 38:109-13, 2007. Pubmed reference: 17302792. DOI: 10.1111/j.1365-2052.2007.01569.x.
2006 Hecht, B.C. :
Sequence analysis of PMel17 as a candidate gene for causing rat-tail syndrome in cattle MSc thesis, Brigham Young University, Provo UT, USA :, 2006.
1999 Schalles, R.R., Cundiff, L.V. :
Inheritance of the "rat-tail" syndrome and its effect on calf performance Journal of Animal Science 77:1144-1147, 1999. Pubmed reference: 10340580.
1989 Ayers, JR., Leipold, HW., Schalles, R., Cole, D. :
Pathological studies of cross-related congenital hypotrichosis in cattle. Zentralbl Veterinarmed A 36:447-52, 1989. Pubmed reference: 2508373.

Edit History

  • Created by Frank Nicholas on 30 Mar 2011
  • Changed by Frank Nicholas on 09 Dec 2011
  • Changed by Frank Nicholas on 18 Jun 2013
  • Changed by Frank Nicholas on 13 Apr 2016