A WGS short-read alignments of an affected dog indicate a homozygous deletion of 17,325 bp. The position of three PCR primers for an allele-specific genotyping assay is indicated. The deletion harbors the entire coding region of SELENOP . The neighboring CCDC152 gene has three annotated transcripts, of which only one is evolutionarily conserved (on top in the figure). The deletion does not extend into this canonical isoform X1 of the CCDC152 gene (CanFam3.1, NCBI annotation release 105). The deletion affects 3’-exons of two alternative CCDC152 transcript isoforms whose biological significance is unknown and which are not annotated in humans. B Sanger sequencing of the diagnostic PCR products confirmed the deletion breakpoints. C Fragment size analysis of the PCR amplification products obtained from genomic DNA of a healthy control ( wt/wt ), an affected dog ( del/del ) and a heterozygous carrier ( wt/del ).