Coronary artery disease (CAD) is a chronic multifactorial disorder of the coronary arteries that develops silently and generally presents at an advanced stage by the time symptoms appear.1,2 It is thus crucial to promptly identify individuals with a high risk of developing this condition. Both genetic and environmental factors contribute to disease progression. Extensive epidemiological research has established the importance of traditional risk factors such as diabetes, hyperlipidemia and hypertension in the development of CAD.3,4 However, some patients can develop vascular disease despite these conventional risk factors being controlled or absent.

Genome-wide association studies (GWAS) have found several genes strongly associated with CAD,5,6 33 of which were formally investigated in the GENEMACOR study designed to investigate the genetic profile of a Portuguese population.7 One of the most significant genes in our population was TCF21, which encodes transcription factor 21 (TCF21), a transcription factor belonging to the cell-type-specific class II basic helix-loop-helix (bHLH) family at chromosome 6q23.2. Recent research shows that vascular smooth muscle cells (VSMCs) can de-differentiate, multiply and migrate in a process known as phenotypic modulation in response to various stimuli. This mechanism influences the evolution of human atherosclerosis. Based on experimental studies, Wirka et al.8 demonstrated a specific knockout of TCF21 in mice with loss of TCF21 expression that significantly inhibited SMC phenotypic modulation, leading to fewer fibroblasts within lesions and plaque instability.8 The G>C TCF21 rs12190287 single-nucleotide polymorphism (SNP) has allelic specificity, with the risk allele C inducing reduced transcriptional activity, in contrast to the protective G allele, which increases this activity. This SNP could therefore affect regulation of gene expression.9,10 Changes in the expression and functionality of target RNAs could play a role in the occurrence of adverse cardiovascular events after a first acute coronary syndrome and potentially be a marker of genetic susceptibility to CAD. Loss of TCF21 function has also been associated with epigenetic alterations in different types of human cancers.11

However, the biological role of TCF21 in determining the fate of epicardial-derived cells and the progression of atherosclerosis remains controversial.

We aimed to investigate the impact of the TCF21 rs12190287 gene variant on the prognosis and progression of atherosclerosis in a coronary disease cohort in the Madeira archipelago.

The interaction between environmental and genetic factors contributes to the pathogenesis of coronary heart disease, and the discovery of new loci and mechanisms will improve the ability to predict cardiovascular risk. Identifying population subgroups that would benefit from lifestyle modification or who are more vulnerable to exposure to environmental factors will be easier, and could enable precision medicine approaches.17,18

TCF21 is a transcriptional gene regulator and is thought to promote plaque stability, reducing clinical events, by enhancing the phenotypic modulation of VSMCs into fibromyocytes that protect against CAD. TCF21 may modulate the response of VSMCs after vascular stress and injury.

Our work aimed to investigate whether the TCF21 rs12190287 G>C variant, associated with CAD by GWAS, could be linked with the risk of MACE in a coronary artery disease population in the Madeira archipelago.

The present study showed significant differences in patient characteristics between MACE and non-MACE groups regarding age, hypertension, physical inactivity, diabetes, and dyslipidemia, with a higher percentage of these classic risk factors in the MACE group. Surprisingly, smoking, an important risk factor for CAD, presented a non-significant risk for MACE in our population. Higashi et al.19 demonstrated that smoking was significantly associated with MACE in female but not in male patients. The pathophysiology underlying the fact that event rates are not as high in males is unclear.19 Other studies demonstrated that current but not past smoking increases the risk of cardiac events and death.20 In our work, subjects who suffered a first ACS were advised to quit smoking, significantly reducing the percentage of current smokers. According to the above-mentioned study, MACE occurrence was higher only in current, not past, smokers.

In our study, estimated GFR in the MACE group was low (<60 ml/min), and it is known that GFR is an important marker of renal impairment and a risk factor for adverse cardiac events. Inrig et al.21 stated that ∼40% of patients who present with CAD have some degree of renal impairment.21,22

As expected, hypertension was more frequent in MACE subjects, as it accelerates the atherosclerotic process, promoting premature CAD and its common sequelae. This is in agreement with Kannel's findings, indicating that preventive management of hypertension should be broadened and requires consideration of the individual's complete cardiovascular risk profile.23

However, the most statistically significant risk factors for MACE development were multivessel disease, physical inactivity, renal impairment, diabetes, and an unfavorable genetic profile with a risk C allele. GWAS and post-GWAS studies have led to substantial progress in understanding the genetic architecture of atherosclerosis progression. Integrating additional ‘omic’ data (genetic and epigenetic), individual clinical data, and environmental influences could improve disease risk stratification and preventive measures.24,25

Our results showed a statistically significant difference between the two study groups (with and without MACE) in the frequency of the TCF21 rs12190287 variant, with a higher frequency of the GG native genotype in the non-MACE group. By contrast, the CC genotype presented a higher frequency in the MACE group. Our results are in line with those of Miller et al.,26 who, almost a decade ago, investigated this variant, located within the 3′-UTR region of the TCF21 gene. They deduced that GC alleles of the TCF21 polymorphism altered the microRNA (miRNA)-224 binding sequence, changing RNA secondary structure and dysregulating TCF21 gene expression. The C risk allele combined with disruption of miRNA-224 and downregulated TCF21 expression increases CAD risk in response to disease-relevant stimuli.26

Abdou et al.28 also studied this SNP in an Egyptian population selected from the Cardiology Department of Menoufia University. They concluded that the CC genotype and C allele of TCF21 (rs12190287 G>C) were genetic risk factors for CAD development.27

Although for a long time the focus was on protein-coding variants, recent research has expanded the spectrum of CAD-associated variants and highlighted the importance of regulatory variants in miRNA sequences and binding sites. Following the contributions of the ENCODE and FANTOM consortia to knowledge of the human genome, significant attention has been paid to so-called genomic noise – miRNAs and long noncoding RNAs (lncRNA) involved in modulating gene expression. Several reports showed that polymorphisms in lncRNA or their target genes play a role in the development of adverse cardiovascular phenotypes. TCF21 protein and miR-224 were expressed in the human diseased vessel wall in vivo with an inversely regulated expression in atherosclerotic lesions.28

Using laser microdissection in endarterectomy samples from vessels with stable or ruptured plaque, Nurnberg et al. employed modern genomic methods to demonstrate that the expression of TCF21 was significantly lower in the ruptured plaque. By decreasing TCF21 expression, the mutated C risk allele may interfere in fibrous cap formation, increasing coronary risk.29 Nevertheless, further studies are needed to assess how changes in TCF21 expression affect the fibrous cap and consequently plaque vulnerability and rupture.

Multivessel disease, diabetes, renal impairment, sedentary lifestyle, and an unfavorable genetic profile were the main significant risk factors for atherosclerosis progression and MACE occurrence in a Portuguese coronary population from the Madeira archipelago. In this population, the C allele in the dominant model (CC+CG) of the TCF21 rs12190287 G>C polymorphism was a significant genetic risk factor for MACE occurrence and a marker of severe prognosis and death. This gene variant may influence fundamental smooth muscle processes in response to vascular stress, accelerating atherosclerosis progression, and may represent a target for future therapies. These findings could impact future preventive and management protocols in this group of patients.

The authors have no conflicts of interest to declare.