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 the Bengal cat breeders, we sent an electronic questionnaire with questions regarding TM, kinship, age at onset, etc. to Swedish Bengal cat breeders who were active breeders during the years 2014-2016. We have collected blood samples, and prepared genomic DNA from in total 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 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 six individuals. Detected genetic variation will be filtered bioinformatically for variants where both parents were heterozygous and the affected kitten was homozygous for the variant allele (i.e., not homozygous for the allele found in the cat's 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 have mapped the Bengal cat sequences to the Leopardic cat genome. In the next stage of the work (2022-2023) we plan to filter out the natural variants of Bengal Cats that are of Leopardic Cat descendent (i.e. have variants 0/0 for Leopardic Cats and 1/1 for domestic cats). It 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.