Our aim is to investigate the prevalence, clinical picture and genetic background of thoracic malformations (TM) such as flat chest in Bengal cats, and to enable a more effective breeding program and better animal health. In collaboration with Bengal cat breeders, we sent an electronic questionnaire with questions regarding TM, kinship, age at onset, etc. to active breeders during the years 2014-2016. We collected blood samples, and extracted genomic DNA from more than 40 Bengal cats (affected kittens, their healthy parents, healthy siblings, as well as cats who never had any offspring with flat chest). The collected samples are all logged and stored in the Dog and Cat Biobank at SLU. Fifteen kittens were examined by computer tomography (CT), autopsied, and sampled for further histopathology, and genetic analyzes. From this material we chose samples for short-read whole genome sequencing of two “father-affected offspring-mother” family trios, i.e., in total seven individuals. Detected genetic variation were filtered bioinformatically for variants where both parents were heterozygous and the affected kittens were homozygous for the variant allele (i.e., not homozygous for the allele found in the domestic cat reference genome). Candidate mutations will be validated by Sanger sequencing of all 40 individuals. Association between genotype and phenotype will be calculated with Fisher's exact test, risk ratio and odds ratio. Arguments for projects extending: During this first part of the project, we mapped the Bengal cat sequences to the Domestic cat genome. These data need to be further evaluated and filtered since we found unexpectedily large number of 1/1 variants. In the next stage of the work we plan to filter out the natural variants of Bengal cat that are of Leopard cat descendent (i.e. have variants 0/0 for Leopard cat and 1/1 in domestic cat). This will also help us to better investigate the Bengal Cats genome in general. Identification of genetic markers or causative mutations in such regions could provide new tools in Bengal cats breeding to select for healthy and sustainable cats.