Spots Geno

Bi-Coloured Spots

It is unsure if this locus has been scientifically described. Because this mutation has so much in common with the bicolour spotting in cats, in reguards to a similar pattern, inheritence, effect on embryological development etc., that the letter designation for this locus, is going to be classed by calling it BiColour spotting and using the symbol "S".

S - BiColour Spotting Semi-dominant.
EffectHeterozygotes = It produces a white belly and almost always a white tail tip, white feet and a white blaze on the face.
EffectHomozygous= Also depending on other present modifiers, it produces markings similar to the harlequin or van marked cat and in some cases a black eyed white as well. "Oddeyes" where one eye is pink and the other a ruby or black colour is also possible, as are "double odd" eyes where both eyes are made pink (which actually makes possible a pink eyed black rat!)
s - Wild Type Recessive.
Effect = No white spotting.

Dominant White Spotting Locus

Usually written "C-kit" in scientific papers, fanciers likely would just use "Ws"

Ws- Dominant White Spotting.
Effect= Heterozygotes; Have white spotting on the belly and usually the face, similar to W, dominantly spotted Mice.
Effect= Homozygous; Mutant rats are Black Eyed White, anemic and are deficient in melanocytes, mast cells, and erythrocytes. In some cases they die in utero.
Veterinarian Resources; Morimoto M, et al.Age-dependent amelioration of hypoplastic anemia in Ws/Ws rats with a small deletion at the kinase domain of c-kit.Blood 1993 Dec 1;82(11):3315-3320
Niwa Y, et al. Anemia and mast cell depletion in mutant rats that are Homozygous at "white spotting (Ws)" locus. Blood. 1991 Oct 15; 78(8): 1936-1941.
Tsujimura T, Et Al. Characterization of Ws mutant allele of rats: a 12-base deletion in tyrosine kinase domain of c-kit gene.. Blood 1991 Oct 15;78(8):1942-1946
ws- Wild Type Recessive.
Effect = No mutation/spotting.

Hooding Locus

This locus is located on Chromosome 14, linked to hm (Hooding modifier), with a distance of 47 +/- 4 cm. The following Alleles tend to overlap- being not fully recessive or dominant, though certain ones (denoted by the traditional capital and lowercase letters) are "more dominant" or "more recessive" in the series.

H(re) - Restricted Hood Pattern Fairly Dominant allele.
Effect= Homozygotes; it causes death within 24 hours of birth.
Effect= Heterozygotes; it decreases the degree of coat pigmentation; males, fertility is best only shortly after peuberty and then wanes or the male becomes completely infertile. Odd Eyes may Occure as well.
Veterinarian Resources; DJ Schaid, HW Kunz and TJ Gill 3d Genetic interaction causing embryonic mortality in the rat: epistasis between the Tal and grc genes . Genetics, Vol 100, 615-632. (Briefly discusses Restricted Hood Pattern on Page 628)
Gumbreck, L.G.. Peliotropic expression of the restricted coat colour gene in rats Journal of heredity Nov/Dec 1971 vol 62-6 pg 356-8

H(e) - Extreem hood pattern fairly Dominant allele.
Effect= Heterozygotes; look similar to H(re). It decreases the degree of coat pigmentation
Effect = Homozygotes; appear BEW with some spots of colour on the face usually.
Veterinarian Resources; Robinson, R. An extreme allele of hooded spotting in the Norway rat. Genetica 1989;79(2):139-41

H - Wild Type fairly dominant allele.
Effect= The Wild type or "non-spotted" allele here. When Homozygous, HH creates a fully coloured rat (commonly called "Self" in fancy).
Effect = When Heterozygous with h, it creates a coloured rat with a white belly (commonly called "Berkshire" in fancy).

h(i) - Recessive
Irish Incompletely recessive to the dominant alleles and incompletely dominant to h. It often creates a white head spot or inverted V shaped blazed with varying amounts of white spotting on the belly. The blaze appears to be suppressed at times, being influenced by other genes.
Effect = Heterozygote; Hh and Hh(i) can be phenotypically similar depending on other modifiers.
Effect = Heterozygote; hh and hh(i) can be phenotypically similar also often with hh(i) having a broken and shortened stripes.
Veterinarian Resources; Robinson R. Head spot and dilute mutations in the Norway rat. Journal of Heredity. 1998 Jan; 89(1): 100-101. PMID: 9487682; UI: 98148662.

h(n) - Notched
Effect = Homozygotes are capped rats with a little wedge of white from the back of the cap pointing inward and down to the nose. Effect =Heterozygote; None.

h - Hooded Incompletely recessive hooding trait.
Effect= Homozygous it creates a pigmented head and white body with a coloured stripe running from the head partway or comletely to the tail.
Effect = Heterozygote; None.
Veterinarian Resources; Stolc V. Linkage of hooded and hood-modifier genes in the rat. Journal of Heredity 1984 Jan;75(1):81.

Head Spot Locus

Hs - Wild Type Dominant.
Effect = None.
Hs - Headspot Recessive.
Effect = Causes a head spot varying in size from a few white hairs to 1 cm or more in diameter. Frequently there is some white spotting on the belly. When bred generationally, selecting for increasing the size of the spot, it often evolves into a blaze, typically off center and/or irregular.
Veterinarian Resources; Robinson R. Head spot and dilute mutations in the Norway rat. Journal of Heredity. 1998 Jan; 89(1): 100-101. PMID: 9487682; UI: 98148662.

Hood-Modifier Locus

Located on Chromosome 14 and linked to hooded with a distance of 47 +/- 4cm, this locus influences the extent of the spotting caused by the hooding locus

Hm(l) - Hood Modification, Long
Effect = Inflences for a long stripe on hooded rats.
Hm(s) - Hood Modification Short
Effect = Influences for a shorter or nonexistant stripe on hooded rats.
Veterinarian Resources; Robinson R. An extreme allele of hooded spotting in the Norway rat. Genetica. 1989; 79(2): 139-141.
Stolc V. Linkage of hooded and hood-modifier genes in the rat. Journal of Heredity 1984 Jan;75(1):81.

Microphthalmia Locus

This locus "Chromosomal" location is: 4q34-q41

Mitf - Wild Type Dominant.
Effect = None.
Mitf(pw) - Micropthalmia pink eyed white
Effect = Small pink eyes, White fur colour, and bones problems (osteosclerosis). Teeth may be missing, small or easily broken, and also erupt later than do their non-affected siblings. Most animals reach adult age, but only males are fertile. Females are steril.
Veterinarian Resources; Moutier R, Ostrowski K, Lamendin H. Microphthalmia: a new recessive mutation in the Norway rat. J Hered 1989 Jan-Feb;80(1):76-8
Opdecamp, K., et al., The rat microphtalmia-associated transcription factor gene (Mitf) maps at 4q34-q41 and is mutaded in the mib rats. Mammalian Genome 9:617-621 (1998)
Mitf(ew) - Micropthalmia eyeless white
Effect = Like Mitf(pw) but eyes are totally missing.

Spotting Lethal Locus

This locus, often refferred to as Ednrb in scientific literature followed with 'sl' in brackets or superscript, has the Chromosomal location of 15 q21-q22

Sl - Wild Type Dominant.
Effect = None.
Above image is from the Gariepy article in the J. Clin. Infest. 1998 Sep 15 article
sl - Spotting Lethal Recessive. Effect =Heterozygote sl/sl rats suffer megacolon (resembling the human Hirschsprung (HSCR) disease) and white coat-color with a small pigmented spot on the head.
Veterinarian Resources; Ceccherini I, Et Al. Interstitial deletion of the endothelin-B receptor gene in the spotting lethal (sl) rat. Human Molecular Genetics 1995 Nov;4(11):2089-2096
Kunieda T, et al. A mutation in endothelin-B receptor gene causes myenteric aganglionosis and coat color spotting in rats. DNA Res 1996 Apr 30;3(2):101-105.
Gariepy CE, et al. Transgenic expression of the endothelin-B receptor prevents congenital intestinal aganglionosis in a rat model of Hirschsprung disease. J Clin Invest. 1998 Sep 15;102(6):1092-101.

Veterinarian Resources; Gariepy CE, et al. Null mutation of endothelin receptor type B gene in spotting lethal rats causes aganglionic megacolon and white coat color. Proc Natl Acad Sci U S A. 1996 Jan 23;93(2):867-72.

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