Osteochondrodysplasia and the c.1024G>T variant of TRPV4 gene in Scottish Fold cats: genetic and radiographic evaluation

Genetic Testing: practical dos and don'ts for cats

PRACTICAL RELEVANCE

A significant number of genetic variants are known for domestic cats and their breeds. Several DNA variants are causal for inherited diseases and most of the variants for phenotypic traits have been discovered. Genetic testing for these variants can support breeding decisions for both health and aesthetics. Genetic testing can also be used to monitor for the health of, or provide targeted therapy for, an individual cat and, more widely, can progress scientific discovery. Technological improvements have led to the development of large panel genetic testing, which can provide many DNA results for a low cost.

CLINICAL CHALLENGES

With the development of large panel genetic testing has come companies that can carry out this service, but which company is best to use may not always be clear - more tests are not necessarily better. Usage and interpretation of genetic data and how the results are presented by commercial laboratories may also be confusing for veterinary practitioners and owners, leading to misinterpretations for healthcare, improper genetic counseling, and poor breed and population management.

EVIDENCE BASE

The information provided in this review draws on scientific articles reporting the discovery, and discussing the meaning and implications, of DNA variants, as well as information from the Online Mendelian Inheritance in Animals (OMIA) website, which documents all the DNA variant discoveries. The author also provides suggestions and recommendations based on her personal experience and expertise in feline genetics.

AUDIENCE

This review is aimed at general practitioners and discusses the genetic tests that can be performed, what to consider when choosing a testing laboratory and provides genetic testing counseling advice. Practitioners with a high proportion of cat breeder clientele will especially benefit from this review and all veterinarians should realize that genetic testing and genomic medicine should be part of diagnostic plans and healthcare for their cat clients.

Efficient generation of cloned cats with altered coat colour by editing of the KIT gene

Coat colour largely determines the market demand for several cat breeds. The KIT proto-oncogene (KIT) gene is a key gene controlling melanoblast differentiation and melanogenesis. KIT mutations usually cause varied changes in coat colour in mammalian species. In this study, we used a pair of single-guide RNAs (sgRNAs) to delete exon 17 of KIT in somatic cells isolated from two different Chinese Li Hua feline foetuses. Edited cells were used as donor nuclei for somatic cell nuclear transfer (SCNT) to generate cloned embryos presenting an average cleavage rate exceeding 85%, and an average blastocyst formation rate exceeding 9.5%. 131 cloned embryos were transplanted into four surrogates, and all surrogates carried their pregnancies to term, and delivered 4.58% (6/131) alive cloned kittens, with 1.53% (2/131) being KIT-edited heterozygotes (KITD17/+). The KITD17/+ cats presented an obvious darkness reduction in the mackerel tabby coat. Immunohistochemical analysis (IHC) of skin tissues indicated impaired proliferation and differentiation of melanoblasts caused by the lack of exon17 in feline KIT. To our knowledge, this is the first report on coat colour modification of cats through gene editing. The findings could facilitate further understanding of the regulatory role of KIT on feline coat colour and provide a basis for the breeding of cats with commercially desired coat colour.