RB1 and posterior cortical atrophy: Altered expression of various oncogenes and tumor suppressor genes namely p53, breast carcinoma susceptibility (BRCA2), cyclin D1, parathyroid adenomatosis gene 1 (PRAD1), retinoblastoma (RB), and hyperparathyroidism 2 (HRPT2) tumor suppressor genes have been implicated in the pathogenesis of PCA.