The PTCH tumour suppressor gene is located on chromosome 9q22, and germline mutations are found in the autosomal dominant condition nevoid BCC (Gorlin) syndrome (NBCCS, MIM 109400), in which patients typically develop numerous BCCs, usually from an early age (Hahn et al, 1996; Johnson et al, 1996). This evidence concerns the gene PTCH1 and nevoid basal cell carcinoma syndrome.