High- and intermediate-risk susceptibility variants in melanoma families from the Mediterranean area: A multicentre cohort from the MelaNostrum Consortium

Background: Most of large epidemiological studies on melanoma susceptibility have been conducted on fair skinned individuals (US, Australia and Northern Europe), while Southern European populations, characterized by high UV exposure and dark-skinned individuals, are underrepresented. Objectives: We report a comprehensive pooled analysis of established high- and intermediate-penetrance genetic variants and clinical characteristics of Mediterranean melanoma families from the MelaNostrum Consortium. Methods: Pooled epidemiological, clinical and genetic (CDKN2A, CDK4, ACD, BAP1, POT1, TERT, and TERF2IP and MC1R genes) retrospective data of melanoma families, collected within the MelaNostrum Consortium in Greece, Italy and Spain, were analysed. Univariate methods and multivariate logistic regression models were used to evaluate the association of variants with characteristics of families and of affected and unaffected family members. Subgroup analysis was performed for each country. Results: We included 839 families (1365 affected members and 2123 unaffected individuals). Pathogenic/likely pathogenic CDKN2A variants were identified in 13.8% of families. The strongest predictors of melanoma were ≥2 multiple primary melanoma cases (OR 8.1; 95% CI 3.3–19.7), >3 affected members (OR 2.6; 95% CI 1.3–5.2) and occurrence of pancreatic cancer (OR 4.8; 95% CI 2.4–9.4) in the family (AUC 0.76, 95% CI 0.71–0.82). We observed low frequency variants in POT1 (3.8%), TERF2IP (2.5%), ACD (0.8%) and BAP1 (0.3%). MC1R common variants (≥2 variants and ≥2 RHC variants) were associated with melanoma risk (OR 1.4; 95% CI 1.0–2.0 and OR 4.3; 95% CI 1.2–14.6, respectively). Conclusions: Variants in known high-penetrance genes explain nearly 20% of melanoma familial aggregation in Mediterranean areas. CDKN2A melanoma predictors were identified with potential clinical relevance for cancer risk assessment.