SDHB and pheochromocytoma: The finding of 1p LOH in a phaeochromocytoma with a germline SDHB mutation is consistent with a two hit hypothesis of tumorigenesis and the frequent occurrence of 1p LOH in sporadic phaeochromocytomas without SDHB mutations suggested that in some cases SDHB inactivation could occur by a combination of LOH and SDHB promoter methylation.