The Role of Genetic Variation in Phenotypic Variability in Loeys-Dietz Syndrome

Loeys-Dietz syndrome (LDS) is a heritable connective tissue disorder caused by pathogenic variants in genes of the transforming growth factor-β (TGF-β) signaling pathway. Although genotype-phenotype correlations have been suggested, comprehensive comparative data across LDS subtypes remain limited. Improved understanding of these correlations is essential to guide individualized surveillance and management strategies.

We conducted a retrospective cohort study of adults with genetically confirmed LDS evaluated between 2018 and 2024 across Mayo Clinic sites. Patients with pathogenic, likely pathogenic, or suspicious variants in TGFBR1, TGFBR2, or SMAD3 were included. Clinical characteristics, physical examination findings, cardiovascular and noncardiovascular manifestations, surgical interventions, and mortality were compared across genotypes. Categorical variables were analyzed using chi-square tests and continuous variables using parametric or nonparametric methods as appropriate.

A total of 93 patients were included (29 TGFBR1, 33 TGFBR2, 31 SMAD3). Demographics and mortality did not differ significantly between groups. Patients with TGFBR1 and TGFBR2 demonstrated trends toward higher rates of ascending aortic aneurysm and aortic dissection compared with SMAD3 patients, though these differences were not statistically significant. Renal artery aneurysms were significantly more common in TGFBR1 patients (13.8%, p = 0.010). SMAD3 patients had significantly higher rates of mitral regurgitation (54.8%, p = 0.04), peripheral neuropathy (29.0%, p = 0.018), and trends toward increased atrial fibrillation and osteoarthritis. A novel association was identified between TGFBR1 variants and migraine, which was significantly more prevalent in this group (62.1%, p = 0.017). The rates of major cardiovascular surgical interventions were high and comparable across all genotypes.

Distinct genotype-phenotype associations exist among LDS subtypes. TGFBR1 and TGFBR2 variants are associated with a greater burden of aggressive vascular disease, whereas SMAD3 variants are linked to mitral valve disease, peripheral neuropathy, and osteoarthritis. We also identified a novel association between TGFBR1 genotype and migraine. These findings reinforce the importance of comprehensive genetic testing to inform personalized surveillance and management strategies in LDS.