Muir-Torre Syndrome With a Frame-shift Mutation in the MSH2 Gene: A Rare Case Report and Literature Review

Muir-Torre Syndrome: A Cutaneous Finding Amidst Broader Malignancies

Muir-Torre syndrome (MTS) is a rare autosomal dominant genetic condition resulting from microsatellite instability which is caused by mutations in DNA mismatch repair genes. This disorder predisposes individuals to skin tumors and visceral malignancies and may be precipitated in immunocompromised or transplant patients. MTS requires close cancer surveillance for the patient and family because of the tendency to develop aggressive internal malignancies and sebaceous carcinoma. Immunohistochemistry and or genetic testing can confirm the diagnosis of MTS. This review offers an update to the guidelines, diagnosis, and management of MTS while offering a unique perspective on an important but lesser-known syndrome.

Identification of SNPs in hMSH3/MSH6 interaction domain affecting the structure and function of MSH2 protein

MutS homolog 2 (MSH2) is a mismatch repair gene that plays a critical role in DNA repair pathways, and its mutations are associated with different cancers. The present study aimed to find out the single nucleotide polymorphisms (SNPs) of MSH2 protein associated with causing structural and functional changes leading to the development of cancer with the help of computational tools. Four different tools for predicting deleterious SNPs (SIFT, PROVEAN, PANTHER, and PolyPhen), two tools each for identifying disease association (PhD-SNP and SNP&GO) and estimating stability (I-mutant and MUPro) were employed. Homology modeling, energy minimization, and root mean square deviation calculation were used to estimate structural variations. Twenty-seven SNPs and five SNPs (double amino acid change) were identified based on a consensus approach that might be associated with the structural and functional change in MSH2 protein. Molecular docking reveals that six SNPs affect the interaction of MSH2 and MSH6. Twelve identified SNPs were reported to be linked with hereditary nonpolyposis, colorectal cancer, and Lynch syndrome. Further, selected SNPs need to be validated in an in vitro system for their precise association with cancer predisposition.

NGS Analysis Confirms Common TP53 and RB1 Mutations, and Suggests MYC Amplification in Ocular Adnexal Sebaceous Carcinomas

Ocular adnexal (OA) sebaceous carcinomas generally demonstrate more aggressive clinical and histopathological phenotypes than extraocular cases, but the molecular drivers implicated in their oncogenesis remain poorly defined. A retrospective review of surgical and ocular pathology archives identified eleven primary resection specimens of OA sebaceous carcinomas with adequate tissue for molecular analysis; two extraocular cases were also examined. Next-generation sequencing was used to evaluate mutations and copy number changes in a large panel of cancer-associated genes. Fluorescence in situ hybridization (FISH) confirmed MYC copy number gain in select cases, and immunohistochemistry to evaluate MYC protein expression. The commonest mutations occurred in TP53 (10/13) and RB1 (7/13). Additional mutations in clinically actionable genes, or mutations with a frequency of at least 25%, included the NF1 (3/12), PMS2 (4/12), ROS1 (3/12), KMT2C (4/12), MNX1 (6/12), NOTCH1 (4/12), PCLO (3/12), and PTPRT (3/12) loci. Low level copy number gain suggestive of amplification of the MYC locus was seen in two cases, and confirmed using FISH. MYC protein expression, as assessed by immunohistochemistry, was present in almost all sebaceous carcinoma cases. Our findings support the concept that alterations in TP53 and RB1 are the commonest alterations in sebaceous carcinoma, and suggest that MYC may contribute to the oncogenesis of these tumors.