Early studies of two dominantly transmitted Mendelian syndromes, multiple cutaneous and uterine leiomyomatosis (MCUL1; OMIM 150800), and hereditary leiomyomatosis and renal cell cancer (HLRCC; OMIM 605839) have implicated a subregion on chromosome 1q43 that contains FH, a gene encoding the tricarboxylic acid cycle (Krebs cycle) fumarate hydratase enzyme [12], [13]. Here, FH is linked to hereditary leiomyomatosis and renal cell cancer.