BRCA2 and obesity due to melanocortin 4 receptor deficiency: The principal known risk factors for breast cancer are age, premature menarchy, late-onset menopause, nulliparity or first pregnancy at late age, exposure to ionizing radiations, presence of mutations in high-penetrance genes (BRCA1, BRCA2 and others), family history [40], alcohol consumption and obesity in postmenopausal women [41].