Confirmation of damaging effect of MSH2 c.2634+1G>C mutation on splicing, its classification and implications for counseling.

INTRODUCTION: Lynch syndrome (LS) is predisposing mainly to colorectal and endometrial carcinomas, but also to urinary tract cancers. LS association with upper urinary tract carcinomas is known, but its association with bladder cancer is not so clear. Confirmation of pathogenicity of detected mutations in LS-associated genes is required for adequate counseling. MATERIAL AND METHODS: Tested young female has family history of two early colorectal and two bladder carcinomas. NGS sequencing revealed MSH2 splice site mutation c.2634+1G>C, which was confirmed by Sanger sequencing. MSH2 cDNA part containing potential splicing change was sequenced. in silico softwares were used to predict the effect of detected mutation on splicing and protein structure. ACMG Guidelines were used for mutation classification. RESULTS: in silico softwares predict damaging effect of detected mutation on splicing and loss of protein-binding domains. cDNA sequencing confirmed this mutation causes exon 15 excision. ACMG Guidelines classify this mutation as Pathogenic. DISCUSSION: MSH2 c.2634+1G>C mutation was not reported previously as LS associated. We confirmed its damaging effect on splicing. in silico tools predict consequent loss of protein domains implicating disrupted protein function. Our results suggest that this mutation should be classified as Pathogenic, and indicate inclusion of bladder cancer in LS cancer spectrum.

Germline mutations in cancer susceptibility genes in high grade serous ovarian cancer in Serbia.

Clinical criteria for genetic testing of genes other than BRCA1/2 in epithelial ovarian cancer (EOC) still do not exist. We assessed the frequency and predictors of deleterious mutations in 19 cancer predisposition genes in high-grade serous ovarian cancer (HGSOC) in Serbia. Next-generation sequencing was used to identify germline mutations in the whole coding regions of a gene panel. Patients' characteristics and sequencing data were summarized with descriptive statistics and compared using chi-square test. Among 131 HGSOC patients, 23 had BRCA1 (17.6%) while 5 had BRCA2 (3.8%) mutation. In addition, 9 (6.9%) pathogenic mutations were detected in other genes including BRIP1 (n = 2;1.5%), CHEK2 (n = 2;1.5%), NBN (n = 3;2.3%) and RAD51C (n = 2;1.5%). Factors that predicted for BRCA1/2 mutations were: breast and ovarian cancers in the same patient (p = 0.031), young age of EOC (p = 0.029), menstrual status (p = 0.004) and family history of cancer (p < 0.0001). However, these factors did not predict for mutations in other cancer susceptibility genes. Applying established referral criteria for genetic testing in Serbia will help identify BRCA1/2 mutation carriers but will not help identify mutations in other cancer susceptibility genes. Until better predictors emerge we should be performing wider genetic testing of EOC in order to identify all mutation carriers.

Hedgehog signaling pathway and vitamin D receptor gene variants as potential risk factors in odontogenic cystic lesions.

OBJECTIVES: Genetic variants in the hedgehog signaling pathway and VDR gene are involved in inflammatory responses and neoplastic transformation. Current study investigated whether single-nucleotide polymorphisms in the hedgehog pathway genes PTCH1, GLI1, SMO, and VDR contribute to susceptibility to odontogenic cystic lesions, odontogenic keratocysts, or inflammatory radicular cysts. MATERIAL AND METHODS: Current study examined polymorphisms of PTCH1 (rs357564) and PTCH1 insertion (IVS1-83), GLI1 (rs2228224, rs2228226), SMO (rs2228617), and VDR (rs2228570, rs731236, rs7975232). A case-control study was conducted on 41 keratocyst cases, 43 radicular cyst cases, and control group of 93 healthy individuals without cystic lesions, radiographically confirmed. Single-nucleotide polymorphisms were assessed by real-time and TaqMan SNP genotyping assays, while PTCH1 insertion 18 bp IVS1-83 polymorphism was determined by PCR. RESULTS: The difference in genotype distribution between keratocyst cases and control group was observed for PTCH1 IVS1-83 and GLI1 rs2228224 polymorphism (p = 0.022, p = 0.030, respectively). Homozygous mutant GG genotype within GLI1 rs2228224 is associated with increased susceptibility for odontogenous keratocysts, with adjusted odds ratio of 4.098 (confidence interval of 1.482-11.328, p = 0.007). CONCLUSION: GLI1 rs2228224 and PTCH1 polymorphisms could predispose to odontogenic keratocysts. CLINICAL RELEVANCE: Variants in hedgehog signaling pathway genes, such as GLI1 and PTCH1, and vitamin D receptor gene, might be considered as molecular risk factors in odontogenic cystic lesions and potential targets for novel therapeutic approaches.

Novel BRCA1 splice-site mutation in ovarian cancer patients of Slavic origin.

Mutations in breast cancer susceptibility gene 1 (BRCA1) lead to defects in a number of cellular pathways including DNA damage repair and transcriptional regulation, resulting in the elevated genome instability and predisposing to breast and ovarian cancers. We report a novel mutation LRG_292t1:c.4356delA,p.(Ala1453Glnfs*3) in the 12th exon of BRCA1, in the splice site region near the donor site of intron 12. It is a frameshift mutation with the termination codon generated on the third amino acid position from the site of deletion. Human Splice Finder 3.0 and MutationTaster have assessed this variation as disease causing, based on the alteration of splicing, creation of premature stop codon and other potential alterations initiated by nucleotide deletion. Among the most important alterations are frameshift and splice site changes (score of the newly created donor splice site: 0.82). c.4356delA was associated with two ovarian cancer cases in two families of Slavic origin. It was detected by next generation sequencing, and confirmed with Sanger sequencing in both cases. Because of the fact that it changes the reading frame of the protein, novel mutation c.4356delA p.(Ala1453Glnfs*3) in BRCA1 gene might be of clinical significance for hereditary ovarian cancer. Further functional as well as segregation analyses within the families are necessary for appropriate clinical classification of this variant. Since it has been detected in two ovarian cancer patients of Slavic origin, it is worth investigating founder effect of this mutation in Slavic populations.

Successful treatment with cladribine of Erdheim-Chester disease with orbital and central nervous system involvement developing after treatment of Langerhans cell histiocytosis.

INTRODUCTION: Erdheim-Chester disease (ECD) is a rare, systemic form of non-Langerhans cell histiocytosis of the juvenile xanthogranuloma family with characteristic bilateral symmetrical long bone osteosclerosis, associated with xanthogranulomatous extra skeletal organ involvement. In ECD, central nervous system (CNS) and orbital lesions are frequent, and more than half of ECD pa tients carry the V600E mutation of the protooncogene BRAF. The synchronous or metachronous development of ECD and Langerhans cell histiocytosis (LCH) in the same patients is rare, and the possible connection between them is still obscure. Cladribine is a purine substrate analogue that is toxic to lymphocytes and monocytes with good hematoencephalic penetration. CASE REPORT: We presented a 23-year-old man successfully treated with cladribine due to BRAF V600E-mutation-negative ECD with bilateral orbital and CNS involvement ECD developed metachronously, 6 years after chemotherapy for multisystem LCH with complete disease remission and remaining central diabetes insipidus. During ECD treatment, the patient received 5 single-agent chemotherapy courses of cladribine (5 mg/m2 for 5 consecutive days every 4 weeks), with a reduction in dose to 4 mg/m2 in a fifth course, delayed due to severe neutropenia and thoracic dermatomal herpes zoster infection following the fourth course. Radiologic signs of systemic and CNS disease started to resolve 3 months after the end of chemotherapy, and CNS lesions completely resolved within 2 years after the treatment After 12-year follow-up, there was no recurrence or appearance of new systemic or CNS xanthogranulomatous lesions or second malignancies. CONCLUSION: In accordance with our findings and recommendations provided by other authors, cladribine can be considered an effective alternative treatment for ECD, especially with CNS involvement and BRAF V600E-mutation-negative status, when interferon-alpha as the first-line therapy fails.