Do mutations in BRCA1/BRCA2 confer a higher risk of skin cancer?

Whole exome profiling and mutational analysis of Ocular Surface Squamous Neoplasia

PURPOSE

To determine genetic mutational profiles in patients with Ocular Surface Squamous Neoplasia (OSSN) using whole exome sequencing.

METHODS

Prospective, case-series study. Patient recruitment was conducted in a single tertiary referral center from April to September 2017. Specimens were obtained by incisional biopsies of tumors from ten eyes with histopathologic confirmation of OSSN. DNA whole exome sequencing and mutation analysis were performed.

RESULTS

Ten patients with clinically-diagnosed OSSN underwent DNA whole exome sequencing analysis. Deleterious mutations in 305 genes known to drive tumor development and progression were found. These mutations centered around two main pathways: DNA repair/cell cycle and development/growth. All ten samples had at least one mutation in a DNA repair/cell cycle gene and all but one sample had one in a development/growth gene. The most common mutation was found in TP53 and HGF (both present in 50% of cases) and mutually exclusive mutations were found in BRCA1 and BRCA2 (50% of cases). Mutations in APC, MSH6, PDGFRA, and PTCH1 were found in 40% of cases. Global mutation analysis identified ultraviolet induced radiation as the only mutational signature present in the dataset.

CONCLUSIONS

Mutations found in samples from patients with OSSN are mainly induced by ultraviolet radiation and occur within two main pathways related to DNA repair/cell cycle and development/growth. There are many clinically available drugs and several others being evaluated in clinical trials that target the genes found mutated in this study, offering new therapeutic options for OSSN.

Double Heterozygosity for BRCA1 Pathogenic Variant and BRCA2 Polymorphic Stop Codon K3326X: A Case Report in a Southern Italian Family

Here, we describe a patient with bilateral breast cancer and melanoma, and with a concomitant double variant, namely p.Gln563Ter in BRCA1 and p.Lys3326Ter in BRCA2. The BRCA2 p.Lys3326Ter (K3326X) (rs11571833) mutation identified in our patient is a debated substitution of thymidine for adenine which is currently regarded as benign polymorphism in main gene databases. Recent studies, however, describe this variant as associated with breast and ovarian tumors. Based on the observation of the cancer’s earliest age of onset in this subject, our purpose was to reevaluate this variant according to recent papers indicating a role of powerful modifier of the genetic penetrance. Genetic testing was performed in all consenting patient’s relatives, and in the collection of the clinical data particular attention was paid to the age of onset of the neoplasia. Following our observation that the our patient with double heterozygosis had an early age of onset for cancer similar to a few rare cases of double mutation for BRCA1 and BRCA2, we also performed an extensive review of the literature relative to patients carrying a double heterozygosity for both genes. In line with previous studies relative to the rare double heterozygosity in both BRCA1/2 genes, we found the earlier onset of breast cancer in our patient with both BRCA1/2 mutations with respect to other relatives carrying the single BRCA1 mutation. The presence of the second K3326X variant in our case induces a phenotype characterized by early onset of the neoplasia in a manner similar to the other cases of double heterozygosity previously described. Therefore, we suggest that during the genetic counseling, it should be recommendable to evaluate the presence of the K3326X variant in association with other pathogenic mutations.