A Japanese woman with Li-Fraumeni syndrome in her 40s underwent comprehensive genetic profiling accompanied by germline data using the Oncoguide NCC Oncopanel, but no germline pathogenic variants in the tumor suppressor gene TP53 were detected. However, careful examination of additional data in the report suggested the presence of a large TP53 deletion. Custom targeting next-generation sequencing and nanopore sequencing revealed a 3.6 kb deletion located between intron 1 and intron 6 of TP53. This finding indicates that the NCC Oncopanel is suggestive for detecting large germline deletions in tumor suppressor genes.