Coat colour, dilution, MLPH-related

Phene ID

4135

Name

Coat colour, dilution, MLPH-related

Phene Name

Cool gray; Larson Blue

OMIA ID

31

Species ID

9913

Characterised

Yes

Characterised Year

2015

In a reversal of the normal sequence of discovery, Li et al. (2016) discovered this phenotype AFTER identifying the causal mutation, by noticing that all Belgian Blue cattle with a particular mutation (MLPH: c.87_96del; p.Glu32Aspfs*1), which inactivates MLPH, have an expected dilution phenotype which the authors called "cool gray".

As reported by Li et al. (2016) [published online in 2015], "In the course of a reverse genetic screen in the Belgian Blue cattle breed, we uncovered a 10-bp deletion (c.87_96del) in the first coding exon of the melanophilin gene (MLPH), which introduces a premature stop codon (p.Glu32Aspfs*1) in the same exon, truncating 94% of the protein." Belgian Blue cattle homozygous for this mutant (and with the appropriate genotype at the epistatic KIT locus) all exhibited a dilution coat colour phenotype (as expected with a mutation that inactivates MLPH), which the authors called "cool gray". Having shown that the Larson Blue "phenotype is not due to inheritance of known mutations causing coat color variation in cattle, including dominant red, Telstar, silver color dilutor, or Dun color", Dikmen et al. (2017) whole-genome sequenced two Larson Blue cows and identified "Three variants with moderate effects on the melanophilin (MLPH) gene were identified in 2 Larson blue cows" but noted that "tools for prediction of the simultaneous effect of 3 missense mutations on the MLPH protein are not available, so additional research is needed to confirm the effect of these AA changes on MLPH function. It is also not known whether the variants identified in MLPH exist in wild-type cows in the Larson herd."