One work found higher rates of p53 and PTCH (both are tumor suppressor genes whose alterations are associated with BCC formation and frequency, but not biological behavior) abnormalities in post ionizing radiation BCCs.
Germline mutations of the human patched gene, PTCH, are responsible for the nevoid basal cell carcinoma (NBCC) syndrome or Gorlin's syndrome, characterized by multiple skin cancers, internal cancers and severe developmental abnormalities.
Basal cell carcinoma (BCC) of the skin is the most common form of cancer, with the majority being caused by mutations in the Patched1 (Ptch1) gene, leading to activation of the Hedgehog (Hh) signaling pathway.
The finding of mutations in the PTCH gene in both Gorlin's syndrome and sporadic basal cell carcinomas has significantly advanced our understanding of the molecular defects that lead to the formation of these tumours.
An early event in BCC formation, loss of heterozygosity (LOH) at the Patched 1 (Ptch1) locus, can be used as a tool to address whether this tumour is monoclonal.
Also, several structural rearrangements of chromosome arm 9q were seen, which may be of particular interest against the background that a gene for familial BCC (Gorlin syndrome), the PTCH gene, maps to this region.
Constitutional PTCH mutations are causative of the nevoid basal cell carcinoma syndrome, and somatic PTCH mutations are found in the vast majority of basal cell carcinomas.
Aberrant sonic hedgehog signalling, mostly due to PTCH1 mutations, has been shown to play a central role in the pathogenesis of basal cell carcinoma (BCC), as well as in basal cell naevus syndrome (BCNS).
Inactivating mutations in Patched-1 (PTCH1), leading to ligand-independent pathway activation, are frequent in several cancer types, but most prominent in BCC.
However, dysregulated hedgehog signaling in human cancers was first described in patients with basal cell carcinoma nevus syndrome and sporadic basal cell carcinoma, in which germline or somatic mutations in pathway components (e.g., smoothened [Smo] and patched-1) lead to constant activation.
In patients suspected of having BCNS or patients with multiple basal cell carcinomas (BCCs) with a special distribution on the body and no mutation detected in blood, it is worthwhile to search for a shared PTCH1 mutation in their BCCs as this can detect postzygotic mosaicism.
Mutations in the human homologue of Drosophila Patched1 (PTCH1) have been found in several common tumours including basal cell carcinoma, medulloblastoma, and rhabdomyosarcoma (RMS).
PTCH was recently proposed as a candidate gene for NBCCS due to its frequent mutation in basal cell carcinomas, the cancer most often associated with this syndrome.
Loss of heterozygosity (LOH) for Patched 1 gene (PTCH) was demonstrated within two of the trichoepitheloma-like tumors and one tumor diagnosed as basal cell carcinoma, and the patient was show to have a PTCH gene deletion.
None of the genes rearranged in the BCC-specific t(9;16)(q22;p13) translocation have been identified, but we hypothesize that the translocation represents the cytogenetic corollary of a tumorigenic recombination of PTCH with an as yet unknown gene in 16p13.
Genetic studies revealed mutations of the following genes: CTNNB1, KIT, CDKN2A, TP53, SMAD4, ERBB4, and PTCH1, with some differences between the matrical and BCC components.
Heterozygous germline PTCH1 mutations are causative of Gorlin syndrome (naevoid basal cell carcinoma), but detection rates > 70% have rarely been reported.
Mutations in the human tumor suppressor gene, Patched-1, are associated with nevoid basal cell carcinoma syndrome characterized by developmental abnormalities and tumorigenesis, such as basal cell carcinoma and medulloblastoma.
It is important to note that emerging therapies for treatment of BCCs in patients with a PTCH1 mutation may not be effective in those with a SUFU mutation.
These pathways include (a) mutated PTCH (in the mitogenic Sonic Hedgehog pathway) and mutated p53 tumor-suppressor gene in basal cell carcinomas, (b) an activated mitogenic ras pathway and mutated p53 in squamous cell carcinomas, and (c) an activated ras pathway, inactive p16, and p53 tumor suppressors in melanomas.
Here, we present a father and daughter with a high propensity for the development of basal cell carcinoma who were heterozygous for a non-coding germline mutation in the 5' untranslated region (UTR) of PTCH-1 (insertion of a surplus CGG triplet at the site of a seven times CGG repeat).