A novel splicing mutation of PTCH1 in a Chinese family with nevoid basal cell carcinoma syndrome

Nevoid basal cell carcinoma syndrome (NBCCS) is a rare autosomal dominant disease characterized by the development of multiple jaw keratocysts and basal cell carcinomas (BCC) and accompanied by diverse phenotypes. The establishment of diagnosis lies on the identification of a heterozygous germline pathogenic variant in the patched homolog 1 gene (PTCH1). PTCH1 has alternative splicing and selective initial coding exon, leading to three types of encoding proteins (PTCHL, PTCHM and PTCHS). The expression of each protein in NBCCS remains ambiguous, especially the importance of the first two exons in translation. Here, we report a Chinese NBCCS family of a novel PTCH1 heterozygous mutation (IVS 2, c.394+1G>T, g.10652G>T) identified by genomic sequencing and reverse-transcription-PCR as aberrant splicing. To the best of our knowledge, this is the first report of NBCCS with a splicing site mutation in intron 2 resulting in exon 2 skipping. Our finding suggests that exon 2 plays an important role in the development of NBCCS and further speculates that the role of longer isoforms PTCHL and PTCHM is crucial in NBCCS, while that of short isoform PTCHS might be dispensable.