SHH and autosomal dominant disease: NBCCS is a rare autosomal dominant disease characterized by developmental abnormalities and a predisposition to various tumours, such as multiple basal cell carcinomas (BCCs), medulloblastoma and rhabdomyosarcoma.7,8PTCH1, which is homologous to Drosophila patched, acts as a tumour suppressor and encodes a putative signal transducer of sonic hedgehog protein (SHH).