CDKN2A/CDK4 status in Brazilian patients meeting clinical criteria for hereditary melanoma: a cross-sectional descriptive trial.

BACKGROUND: Melanoma is the most lethal skin cancer, and its incidence has increased worldwide. About 10% of cases are classified as hereditary melanoma (HM). CDKN2A and CDK4 are the major high-risk genes. Families are also more prone to develop pancreatic cancer, and different forms of oncological surveillance are recommended. OBJECTIVES: Describe the prevalence of CDKN2A/CDK4 germline mutations in melanoma-prone patients and their phenotypic and histopathological features. METHODS: A total of 69 patients meeting the clinical criteria for HM were included in this cross-sectional descriptive study. Amplification by PCR and genomic sequencing were used. The variants were classified according to American College of Medical Genetics (ACMG) criteria. RESULTS: The mean age at first diagnosis of melanoma was 44.8 years (SD ± 17.83). Most patients had phototype II (44.9%), more than 50 melanocytic nevi (76.8%), atypical nevus syndrome (72.5%), history of sunburn (76.8%), and multiple primary melanomas without a family history of this tumor (74.3%). Two hundred melanomas were observed. Most tumors had a Breslow index ≤1.0 mm (84.5%), location in the trunk (60.5%), and superficial spreading histological subtype (22.5%). Four variants were found in CDKN2A exons in seven patients (c.305C>A, c.26T>A, c.361G>A e c.442G>A), two variants in the 5'UTR region in five patients (c.-25C>T and c.-33G>C), and two variants in the 3'UTR region in 21 patients (c.*29C>G and c.*69C>T). One likely pathogenic variant (c.305C>A) was identified in one patient (1.4%). No variant was found in CDK4. CONCLUSION: The prevalence of CDKN2A mutations was 1.4% in Brazilian patients meeting clinical criteria for HM.

Constitutional and somatic methylation status of DMRH19 and KvDMR in Wilms tumor patients.

The most frequent epigenetic alterations in Wilms tumor (WT) occur at WT2, assigned to 11p15. WT2 consists of two domains: telomeric domain 1 (DMRH19) that contains the IGF2 gene and an imprinted maternally expressed transcript (H19) and centromeric domain 2 (KvDMR) that contains the genes KCNQ1, KCNQ1OT1 and CDKN1C. In this work, we used pyrosequencing and MS-MLPA to compare the methylation patterns of DMRH19/KvDMR in blood and tumor samples from 40 WT patients. Normal constitutional KvDMR methylation indicated that most of the epigenetic alterations in WT occur at DMRH19. Constitutional DMRH19 hypermethylation (HM DMRH19) was observed in two patients with Beckwith-Wiedemann syndrome. Pyrosequencing and MS-MLPA showed HM DMRH19 in 28/34 tumor samples: 16/34 with isolated HM DMRH19 and 12/34 with concomitant HM DMRH19 and KvDMR hypomethylation, indicating paternal uniparental disomy. With the exception of one blood sample, the MS-MLPA and pyrosequencing findings were concordant. Diffuse or focal anaplasia was present in five tumor samples and was associated with isolated somatic HM DMRH19 in four of them. Constitutional 11p15 methylation abnormalities were present in 5% of the samples and somatic abnormalities in the majority of tumors. Combined analysis of DMRH19/KvDMR by pyrosequencing and MS-MLPA is beneficial for characterizing epigenetic anomalies in WT, and MS-MLPA is useful and reliable for estimation of DNA methylation in a clinical setting.

Portuguese c.156_157insAlu BRCA2 founder mutation: gastrointestinal and tongue neoplasias may be part of the phenotype.

We have screened BRCA2 c.156_157insAlu founder mutation in a cohort of 168 women with diagnosis of breast cancer referred for genetic counseling because of risk of being carriers of hereditary breast and ovarian cancer syndrome. Portuguese founder mutation BRCA2 c.156_157insAlu was identified in three unrelated breast cancer probands. Genotyping identified a common haplotype between markers D13S260 and D13S171, and allele sizes were compatible to those described in the Portuguese families. Allele sizes of marker D13S1246, however, were concordant in two families, suggesting that the haplotype may be larger in a subset of families. Tumor phenotypes in Brazilian families seem to reinforce the high prevalence of breast cancer among affected males. However, an apparent excess of gastrointestinal and tongue neoplasias were also observed in these families. Although these tumors are not part of the phenotypic spectrum of hereditary breast and ovarian cancer syndrome, they might be accounted for by other risk alleles contained in the founder haplotype region.