This is a spontaneous eight nucleotide (CGACGAGT) deletion at chromosome 15 position 25,781,267-274 bp (GRCm38). The deletion disrupts exon 25 and produces a frame shift expected to truncate the full-length and all three headless transcripts following aa 948. Immunoblot of whole brain lysates from 1-month-old mutant mice revealed combined deletion of the full-length and headless forms, confirming complete loss of encoded protein. (J:222308, J:256438)