SDHD and Cowden syndrome 1: In recent years, other CS predisposition genes such as KILLN (Killin), SDHB (Succinate Dehydrogenase Complex Iron Sulfur Subunit B), SDHC (Succinate Dehydrogenase Complex Subunit C), SDHD (Succinate Dehydrogenase Complex Subunit D), PIK3CA (Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha), AKT1 (AKT serine/threonine kinase 1), and SEC23B (SEC23 Homolog B, COPII Coat Complex Component) have been identified in CS patients [3].