Abstract
BACKGROUND/OBJECTIVES: Fresh frozen (FF) samples are routinely used to isolate high-molecular-weight intact genomic DNA. However, when FF samples are not available, archived formalin-fixed paraffin-embedded (FFPE) tissue samples often represent the only available material in clinical research. Due to formaldehyde-induced degradation of nucleic acids they pose special challenges for genetic investigations. In this study we compare whole-genome sequencing results on intact DNA versus fragmented DNA derived from FFPE samples of three dogs. METHODS: We prepared matched libraries from FF and FFPE samples of three dogs affected by an inherited disease, EFNB3-related congenital mirror movement disorder 1 (CMM1). Paired-end short-read sequencing data were obtained on an Illumina sequencer and analyzed with adapted workflows for FF or FFPE data, respectively. RESULTS: The data between FF and FFPE samples were largely consistent. FF data showed a superior variant call accuracy, as expected. However, the data quality from the FFPE samples was sufficient to correctly identify the causal variant in EFNB3. CONCLUSIONS: This pilot study demonstrates the feasibility of using FFPE samples from dogs for whole-genome sequencing and the detection of germline variants. Using FFPE samples in the analysis of suspected inherited diseases in domestic animals may represent a valuable approach in veterinary genetics if no other samples are available.