A SLC45A2 mutation is strongly associated with the cream dilution in Baroque donkeys.

Overview

• This research identifies a specific genetic mutation in the SLC45A2 gene that is strongly linked to the cream coat color dilution found in Baroque donkeys.
• The study suggests that this mutation follows an autosomal recessive inheritance pattern and is likely the main cause of the cream coloration in these donkeys.

Background

• Baroque donkeys are a domesticated breed known for their distinctive and charismatic cream-colored coat, commonly found in European parks and zoos.
• The genetic basis for this cream coat color was previously unknown.
• Because the coat color genetics in horses are relatively well studied, the researchers used this knowledge to identify possible candidate genes responsible for the cream color in Baroque donkeys.

Research Approach

• The study focused on sequencing the SLC45A2 gene because it was identified as a strong candidate gene related to coat color dilution based on prior research in horses.
• A total of 77 domesticated donkeys, 11 wild equids, 1 mule, and 2 domestic horses were sampled to provide genetic comparison.
• Researchers sequenced all exons and flanking intronic regions of the SLC45A2 gene, covering 2774 base pairs in total.

Key Findings

• Sequence comparisons revealed a mutation exclusively found in exon 7 of the SLC45A2 gene, specifically at c.1457C>T leading to the amino acid substitution p.Ala486Val in the transmembrane region 11.
• This mutation is strongly associated with the cream coat color observed in Baroque donkeys.
• Family studies indicated that the mutation follows an autosomal recessive inheritance pattern, meaning that two copies of the mutated gene are necessary for the cream coat phenotype to be expressed.
• The coat color spectrum in Baroque donkeys ranges from nearly white to a gold shade, suggesting possible contributions from other pigmentation genes.
• However, the study investigated two other key pigmentation genes (not explicitly named in the abstract, likely referencing MC1R and ASIP) and found no significant mutations in these genes that would affect the cream coloration.

Significance and Implications

• The identification of the p.Ala486Val mutation in SLC45A2 provides a clear genetic marker for the cream dilution phenotype in Baroque donkeys, useful for breeders and conservationists.
• The autosomal recessive inheritance model enables prediction of coat color outcomes in offspring when parent genotypes are known.
• This work adds to the understanding of coat color genetics in equids, paralleling what is known in horses, and highlights the role of SLC45A2 in mammalian pigmentation.
• The absence of other significant mutations in pigmentation genes suggests that this single mutation is the primary cause of the cream coat, simplifying genetic testing.

Additional Notes

• The article contains a German language summary reiterating the main points of the study.
• The study highlights that while the cream dilution phenotype is strongly tied to SLC45A2, base coat color variation might still involve other genes but none were identified as impactful in this donkey population.
• Further research could explore whether additional genetic factors modulate the range of cream color shades or interact with the SLC45A2 mutation.