High SCAD polygenic risk score strongly associates with familial SCAD risk

In contrast, no rare variants in genes previously implicated in SCAD were identified as a likely cause in any family. The findings published in JAMA Cardiology support the hypothesis that common polygenic variants contribute to the familial clustering of SCAD cases, potentially more so than rare variants of large effect size.

"The genetic association study comprising 13 families with SCAD, 173 individuals with sporadic SCAD, and 1127 controls revealed that a polygenic risk score for SCAD was associated with significantly higher odds of disease in both familial and sporadic SCAD compared with healthy controls," the researchers reported.

Common genetic variants play a critical role in all forms of SCAD, can potentially explain familial clustering, and further stress the complex genetic aetiology of the disease, the study stated.

Spontaneous coronary artery dissection is a poorly understood cause of acute coronary syndrome (ACS) that predominantly affects women. To date, evidence indicates a complex genetic architecture, while a family history is reported for a minority of cases. Therefore, Ingrid Tarr, Victor Chang Cardiac Research Institute, Darlinghurst, Australia, and colleagues aimed to determine the contribution of rare and common genetic variants to SCAD risk in familial cases, the latter via the comparison of a polygenic risk score with those with sporadic SCAD and healthy controls.

The study analyzed families with SCAD, individuals with sporadic SCAD, and healthy controls. For all participants, genotyping was undertaken. Participants' recruitment was done between 2017 and 2021. A polygenic risk score for SCAD was calculated for all participants. The presence of rare variants in genes associated with connective tissue disorders (CTD) was also evaluated. Recruitment of individuals with SCAD was done via social media or from a single medical centre. The study used a previously published control database of healthy elderly individuals.

PRS for SCAD comprised of 7 single-nucleotide variants. The study's main outcomes were disease status (sporadic SCAD, familial SCAD, or healthy control) associated with PRS.

The study included 13 families with SCAD (27 affected and 12 unaffected individuals), 173 individuals with sporadic SCAD, and 1127 healthy controls. A total of 188 individuals with SCAD were female, including 25 of 27 with familial SCAD and 163 of 173 with sporadic SCAD; of 12 unaffected individuals from families with SCAD, 6 were female; and of 1127 healthy controls, 672 were female.

The study revealed the following findings:

• Compared with healthy controls, the odds of being an affected family member or having sporadic SCAD were significantly associated with a SCAD PRS (where the odds ratio [OR] represents an increase in odds per 1-SD increase in PRS) (affected family member: OR, 2.14; sporadic SCAD: OR, 1.63). This association was not seen for unaffected family members (OR, 1.03) compared with controls.
• Those with familial SCAD were overrepresented in the top quintile of the control PRS distribution (OR, 3.70); those with sporadic SCAD showed a similar pattern (OR, 2.51).
• Affected individuals within a family did not share any rare deleterious variants in CTD-associated genes.

"The findings showed a significant role of extreme aggregation of common genetic risk in familial clustering of SCAD as well as in sporadic case predisposition, although further study is required," the researchers wrote.

Reference:

Tarr I, Hesselson S, Troup M, et al. Polygenic Risk in Families With Spontaneous Coronary Artery Dissection. JAMA Cardiol. Published online January 24, 2024. doi:10.1001/jamacardio.2023.5194