Identification of 23TGFBR2and 6TGFBR1gene mutations and genotype-phenotype investigations in 457 patients with Marfan syndrome type I and II, Loeys-Dietz syndrome and related disorders

TGFBR1 and TGFBR2 gene mutations have been associated with Marfan syndrome types 1 and 2, Loeys-Dietz syndrome and isolated familial thoracic aortic aneurysms or dissection. In order to investigate the molecular and clinical spectrum of TGFBR2 mutations we screened the gene in 457 probands suspected of being affected with Marfan syndrome or related disorders that had been referred to our laboratory for molecular diagnosis. We identified and report 23 mutations and 20 polymorphisms. Subsequently, we screened the TGFBR1 gene in the first 74 patients for whom no defect had been found, and identified 6 novel mutations and 12 polymorphisms. Mutation-carrying probands displayed at referral a large clinical spectrum ranging from the Loeys-Dietz syndrome and neonatal Marfan syndrome to isolated aortic aneurysm. Furthermore, a TGFBR1 gene mutation was found in a Shprintzen-Goldberg syndrome patient. Finally, we observed that the yield of mutation detection within the two genes was very low : 4.8% for classical MFS, 4.6% for incomplete MFS and 1% for TAAD in the TGFBR2 gene; 6.2%, 6.2% and 7% respectively in the TGFBR1 gene; in contrast to LDS, where the yield was exceptionally high (87.5%).