Genetic profiling of basal cell carcinomas detects postzygotic mosaicism in basal cell naevus syndrome

Mutations of PTCH1 gene in two pedigrees with bifid rib-basal cell nevus-jaw cyst syndrome

Two male patients with bifid rib-basal cell nevus-jaw cyst syndrome (BCNS) were admitted to Department of Stomatology, the First Affiliated Hospital of Bengbu Medical College due to radiological findings of multiple low density shadows in the jaw. Clinical and imaging findings showed thoracic malformation, calcification of the tentorium cerebellum and falx cerebrum as well as widening of the orbital distance. Whole exon high-throughput sequencing was performed in two patients and their family members. The heterozygous mutations of c.C2541C>A(p.Y847X) and c.C1501C>T(p.Q501X) in PTCH1 gene were detected in both patients. Diagnosis of BCNS was confirmed. The heterozygous mutations of PTCH1 gene locus were also found in the mothers of the two probands. Proband 1 showed clinical manifestations of low intelligence, and heterozygous mutations of c.C2141T(p.P714L) and c.G3343A(p.V1115I) were detected in FANCD2 gene. Proband 2 had normal intelligence and no FANCD2 mutation. The fenestration decompression and curettage of jaw cyst were performed in both patients. Regular follow-up showed good bone growth at the original lesion, and no recurrence has been observed so far.

Molecular mechanism of extracutaneous tumours in patients with basal cell nevus syndrome

Basal cell nevus syndrome (BCNS) is a rare genetic disorder accompanied by a broad variety of tumours, of which basal cell carcinomas and odontogenic keratocysts are the most common. BCNS is caused by a germline or postzygotic mutation in either PTCH1 or SUFU As BCNS is a rare disease, it is difficult to establish whether less frequently occurring tumours are actually part of the syndrome. In this study, the molecular mechanism behind four extracutaneous tumours in patients with BCNS was elucidated. A leiomyoma of the testis and meningioma were confirmed to be associated with BCNS in two patients by presence of a second mutation or loss of heterozygosity in PTCH1 In a meningioma of a patient with a mosaic postzygotic PTCH1 mutation an association could not be conclusively confirmed. SUFU was probably not involved in the development of a thyroid carcinoma in a patient with a germline SUFU mutation. Hence, we have proven that meningioma and leiomyoma of the testis are rare extracutaneous tumours that are part of BCNS.

A guideline for the clinical management of basal cell nevus syndrome (Gorlin-Goltz syndrome)

The overall objective of this guideline is to provide up-to-date, evidence-based recommendations for the diagnosis and surveillance of all symptoms of children and adults with either basal cell nevus syndrome (BCNS), a clinical suspicion of BCNS, or a parent with BCNS. In the last two groups the guidelines should be followed until the diagnosis of BCNS can be rejected with certainty. The guideline aims to: - Update and expand on the previous guidelines by an appraisal of all relevant literature from January 2011 up to January 2021 - Address important, practical, clinical questions relating to the primary guideline objective - Provide guideline recommendations - Discuss potential developments and future directions.

Linear basal cell nevus with a novel mosaic PTCH1 mutation

The patched tumor suppressor gene (PTCH1) encodes a receptor, which is a key component of the hedgehog signalling pathway. Mutations in PTCH1 are implicated in the development of sporadic basal cell carcinomas (BCC), as well as those in Gorlin Syndrome. Rarely, BCCs may develop in a linear pattern along lines of Blaschko due to cutaneous mosaicism. In cases in which there are other features of Gorlin syndrome, genomic analysis has demonstrated lesional mutations in the Hedgehog signalling pathway. Causative mutations, however, have not been firmly demonstrated in the cases of linear and segmental BCCs in otherwise healthy individuals. Herein, we report a case of a 31 year-old Caucasian woman with linear development of multiple superficial BCCs in a Blaschkoid distribution without other characteristic findings of Gorlin syndrome. Genomic analysis of lesional skin by whole-exome sequencing identified a novel heterozygous mutation PTCH1: NM_000264.3, Exon 15, c.2336-2337insGGTAGGA, p.Asp779Glufs*13 in PTCH1, shared by two discrete samples within the lesion, while no mutations were found in the non-lesional skin or peripheral blood. Given the young age of our patient and linear distribution of BCCs on non-sun exposed skin, our findings suggest segmental mosaicism. The patient was treated with topical 5% imiquimod with histologically confirmed clearance of BCCs in 2 months.