Frameshift Mutation in KIT Spotted in a Pair of Particolored Arabian Camels

Coat color variation was valued throughout animal domestication. However, pigmentation is often associated with other behavioral or health traits, due to the phenomenon of genetic pleiotrophy. In domestication experiments, researchers noted that breeding for tame behavior in foxes, mink, and rats also resulted in novel white spotting. The dromedary camel is an important domestic species selected for draught, meat, milk, racing, and riding. Though usually with a uniform coat of varying shades of brown or black, there are rare spotted or fully white populations. We collected blood from several camels as part of a genetic diversity project. We then extracted DNA and performed Illumina sequencing on eight solid camels and one white spotted camel. KIT was targeted as a strong candidate gene due to phenotypic similarities with dominant white horses. Sequencing reads and the predicted dromedary KIT cDNA were aligned to genomic scaffolds containing portions of KIT. A single base deletion was detected in the spotted camel, and was absent in the other eight animals. Sanger sequencing of the spotted camel and its spotted herdmate confirmed the presence of a heterozygous deletion. The resulting frameshift introduces a stop codon five amino acids downstream, indicating this mutation is a strong functional candidate for the white spotting phenotype. Similar KIT mutations are well tolerated in the horse, with no associated health defects other than theorized homozygous embryonic lethality. Therefore, while there may potentially be reduced fertility among interbred white spotted camels, data in other species suggests individual health may not be impacted.