In approximately 50–85% of BCNS cases sequence variations of the PTCH1 gene, in 6–21% duplication or deletion of exon(s) of the PTCH1 gene, in approximately 5% sequence variation of the SUFU gene, and in 1% deletion or duplication of exon(s) of the SUFU gene are at the background of the disease [4]. The gene discussed is PTCH1; the disease is nevoid basal cell carcinoma syndrome.