Categories: Pigmentation phene

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal dominant

Disease-related: no

Key variant known: yes

Year key variant first reported: 2021

Species-specific symbol: Ti

Species-specific description: "Ticked" is the term applied to the non-tabby, agouti coat colour pattern that is the trade mark of Abyssinian cats. Its traditional symbol is T(a).

History: Lyons et al. (2021): "Ticked (previously known as Tabby), was the first locus to be regionally positioned to the centromeric region of cat chromosome B1q (Lyons et al. 2006). The ticked allele, formerly known as tabby – Aby (Ta), presents as a cat devoid of patterning, implying no stripes, blotches, swirls or spots – no tabby markings within the cat coat coloration ... . This allele is dominant, suppressing patterning, and hence epistatic to the LVRN Tabby locus, which controls the type of pattern, including mackerel (stripes) or classic (blotched) pattern."

Mapping: Lyons et al. (2006) mapped Abyssinian (Ta-) (at that time assumed to be an allele of the tabby locus) to chromosome B1. Eizirik et al (2010) showed that the ticked phenotype is inherited independently of the two main tabby alleles, namely mackerel and blotched. The ticked locus maps to a 3.8Mb region on cat chromosome B1. The term "tabby locus", with its two alleles mackerel and blotched, is now reserved for a locus on cat chromosome A1 (see Coat colour, tabby; OMIA 001429-9685).

Molecular basis: Lyons et al. (2021; published 29 March): "The cat reference genome (Cinnamon, the Abyssinian) has the ticked phenotype and the variant dataset and coat phenotypes from the 99 Lives Cat Genome Consortium (195 cats) were used to identify candidate genes and variants associated with the Ticked locus. ... two variants in Dickkopf Wnt Signaling Pathway Inhibitor 4 (DKK4), a p.Cys63Tyr (B1:4[2]621481, c.188G>A) and a less common p.Ala18Val (B1:42620835, c.53C>T) variant are suggested as two alleles influencing the Ticked phenotype. ... Cinnamon was a compound heterozygous for the p.Cys63Tyr/p.Ala18Val variants." In a study in which they "applied morphological and single-cell gene expression analysis to fetal skin of domestic cats", Kaelin et al. (2021; published 7 Sept) discovered the same two variants having the same phenotypic effects.

Breeds: Abyssinian (Cat) (VBO_0100000), Burmese (Cat) (VBO_0100053), Oriental Shorthair (Cat) (VBO_0100184), Singapura (Cat) (VBO_0100224).
Breeds in which the phene has been documented. (If a likely causal variant has been documented for the phene, see the variant table breeds in which the variant has been reported).

Associated gene: