Cardiovascular pathology, inheritance and prognosis in a familial cohort of Loeys-Dietz type III.

INTRODUCTION: Loeys-Dietz syndrome (LDS) is a heritable disease that is the result of dysregulation of the transforming growth factor beta (TGFβ) pathway. The pathogenic variants associated with the condition are linked to aortic aneurysms and dissections along with other cardiovascular and non-cardiovascular abnormalities. LDS type III is associated with pathogenic variants in the SMAD3 gene responsible for signally in the TGFβ pathway. Most of the current knowledge of LDS stems from studies of LDS I and II patient with limited data on large cohorts of LDS III patients. We sought to identify the prevalence and course of cardiovascular diseases in a large familial cohort of LDS III patients and also to compare these findings with a previously described cohort of similar size with the identical pathogenic variant.

METHODS: The cohort was identified by systematic genetic screening of a familial cohort identified through a single proband. Data was collected from retrospective chart review of patients identified to be affected by the syndrome.

RESULTS: Screening of 97 patients identified 19 patients (16 through genetic testing and 3 through phenotypic screening of untested direct descendants of genetically positive individuals). The prevalence of cardiovascular abnormalities was 84%. There was significant intrafamilial phenotypic variability within the cohort with the predominant cardiovascular abnormality being mitral valve disease followed by aortic disease. 92% of patients >18 years of age had osteoarthritis which is a further hallmark of LDS III.

CONCLUSION: LDS III sets itself apart from the more widely studied LDS types I and II cardiovascular phenotypes by presenting later in life and tending to be more strongly associated with mitral valve disease.