Abstract P331: Upregulated TBX1 by genetic variants are associated with human congenital heart disease

Congenital heart disease (CHD) is the most common human birth defect worldwide. The cause of CHD is so far not well understood. Uncovering genetic factors leading to CHD is still a pressing task to be solved. TBX1 is one of the transcription factors early expressed in embryonic cardiac progenitors. In animal models, imbalanced TBX1 activity leads to cardiac defects. Given the dosage effect of TBX1, it is possible that genetic variant altering TBX1 function or expression level would affect heart development and contribute to CHD. In order to study the association of genetic variants of TBX1 and CHD susceptibility, we performed genetic screening in 409 CHD patients and 213 healthy controls. Bioinformatic and in vitro functional studies were performed to evaluate the impact of genetic variants. One single nucleotide polymorphism (SNP), rs41260844, in TBX1 promoter region was identified to be associated with CHD. The minor allele of rs41260844 is associated with higher CHD risk and shows increased TBX1 promoter activity (Fig A). Further study showed the minor allele attenuates TBX1 promoter binding affinity with nuclear protein(s) (Fig B). In addition, a novel case-specific missense rare mutation, p.P164L, in T-box domain was identified and predicted as a deleterious mutation. Functional analysis showed a trend of increased TBX1 function with the rare mutation. In summary, we concluded that a higher TBX1 expression level or activity is associated with CHD susceptibility, which could affect TBX1 downstream targets and thus disrupt the balance of the complex regulation network during cardiogenesis.