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The equine graying with age mutation of the STX17 gene: A copy number study using droplet digital PCR reveals a new pattern
Author(s) -
NowackaWoszuk J.,
Mackowski M.,
StefaniukSzmukier M.,
Cieslak J.
Publication year - 2021
Publication title -
animal genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 81
eISSN - 1365-2052
pISSN - 0268-9146
DOI - 10.1111/age.13044
Subject(s) - biology , warmblood , genotyping , genetics , copy number variation , digital polymerase chain reaction , genotype , copy number analysis , amplicon , tandem exon duplication , gene , gene duplication , horse , microbiology and biotechnology , polymerase chain reaction , genome , paleontology
Summary The equine graying with age causative mutation in the syntaxin‐17 gene ( STX17 ) has been known for over a decade, but proper genotyping of this variant remains challenging due to its molecular character (4.6‐kb tandem duplication). Precise information on gray mutation status is important for horse breeders and veterinarians, since gray homozygous horses are more prone to developing aggressive melanoma tumors than heterozygotes. Since recent studies have confirmed that droplet digital PCR is a valuable technique for copy number analysis, we decided to investigate whether this method can be used for accurate genotyping of the horse graying‐related variant and established the copy numbers of the 4.6‐kb fragment in the available cohort ( n = 75) of gray and nongray horses of various breeds. Surprisingly, we found that our STX17 genotype results varied from what has been previously published, suggesting that gray phenotype is associated with the presence of six ( GG ) or four ( Gg ) copies of studied region. All the examined nongray horses ( gg ) have the two copies of these fragments. This new pattern and its inheritance were also confirmed by an analysis conducted for the Polish Warmblood horse family. We noted no further copy number variation in the entire tested samples set. Our study confirmed the usefulness and accuracy of droplet digital PCR for genotyping STX17 gene variant. Further studies on a broader range of materials are needed to fully understand the origin and molecular structure of the graying causative mutation in the horse STX17 .