CD36 Variant Emerges as a Major Genetic Driver of Dilated Cardiomyopathy in African Ancestry Cohorts
Dilated cardiomyopathy has long been framed around sarcomeric genetics, with TTN truncating variants occupying the center of most discussions about inherited risk. This multicohort analysis challenges that hierarchy in individuals of predominantly African ancestry. Across four U.S. datasets, a common nonsense variant in CD36 carried a larger population burden than TTN truncating variants, despite TTN remaining the stronger individual-level predictor of disease risk.
The study pulled together exome or genome sequence data and phenotype information from the All of Us Research Program, the Million Veteran Program, the Penn Medicine Biobank, and the DCM Precision Medicine Study. In total, 82,623 individuals of predominantly African ancestry were included, with a mean age of 53.4 years and 47,124 male participants. Among them, 1,316 had dilated cardiomyopathy. The size of the cohort matters because the question is not only which variant raises risk most sharply for one person, but which variant explains the largest share of disease across a population. In that framework, frequency becomes as important as penetrance.
Homozygosity for the CD36 Y325* risk allele was associated with a markedly higher odds of dilated cardiomyopathy, with an odds ratio of 4.8. Heterozygous carriers also had elevated risk, with an odds ratio of 1.4. TTN truncating variants remained strongly associated with disease, with an odds ratio of 8.5 in participants of African ancestry. The contrast is clinically instructive: TTN appears more potent per carrier, yet CD36 appears more consequential at the population level because it is more common in the ancestry group studied.
That distinction changes how genetic burden is interpreted at the bedside and in public health planning. A rare, high-effect variant can explain compelling familial clustering, but a more prevalent variant with moderate-to-high effect can quietly account for a larger fraction of cases across a community. In African ancestry populations, CD36 fits that pattern.
Population Attributable Burden Shifts the Genetic Center of Gravity
Among the 1,316 African ancestry participants with dilated cardiomyopathy, 33 were homozygous for CD36, representing 2.5% of cases. Fifty-six individuals, or 4.3%, carried TTN truncating variants. Another 16 cases, 1.2%, carried pathogenic or likely pathogenic variants in other established high-confidence DCM genes. Those numbers may seem modest when viewed in isolation, but they become more revealing once converted into population attributable fractions.
When heterozygous and homozygous CD36 carriers were combined, the population attributable fraction for CD36 reached 9.0%, divided into 6.2% for heterozygous carriers and 2.8% for homozygous carriers. TTN truncating variants accounted for a smaller population attributable fraction of 3.7%. In practical terms, more disease in this ancestry group was statistically linked to CD36 than to TTN, even though TTN carried the stronger individual odds ratio.
One sentence captures the clinical consequence plainly: a variant can be less penetrant than TTN and still matter more for the total burden of disease if it is common enough. This is the kind of pattern that ancestry-aware genomic studies are designed to detect, and it explains why disease architecture can differ sharply between populations even when the phenotype appears the same in clinic.
The biological plausibility of the finding is also compelling. CD36 encodes a membrane glycoprotein involved in fatty acid uptake and metabolic signaling, and cardiac energetics depend heavily on tight coordination between substrate handling and myocardial work. A loss-of-function nonsense variant can disturb that balance in ways that may promote ventricular dysfunction over time. By contrast, TTN truncating variants disrupt a core sarcomeric structural protein and have long been recognized as a major monogenic cause of dilated cardiomyopathy. The new data do not diminish TTN; they reposition CD36 as a major contributor in a population where it has been underweighted by historically Eurocentric gene discovery.
Representation in Genomics Now Has Direct Diagnostic Consequences
The most important clinical message is not simply that one variant outranked another in a statistical model. It is that the genetic architecture of dilated cardiomyopathy is not uniform across ancestry groups, and the mismatch has real implications for diagnosis, family counseling, and variant interpretation. If the reference frame is too narrow, a clinically important contributor to disease can be missed or undervalued. That risk is especially relevant in cardiomyopathy, where genetic testing is increasingly used to support causality, cascade screening, and risk stratification.
These findings also argue for a more deliberate approach to ancestry-specific reference data when interpreting sequence results. A variant that appears uncommon in one population may be frequent enough in another to shape disease risk at scale. The converse is also true: a gene long treated as dominant in one ancestral context may not explain the majority of cases elsewhere. In this study, the combined evidence from four U.S. cohorts makes the point forcefully: African ancestry participants with DCM carried a genetic burden that could not be fully described by the standard emphasis on TTN alone.
The cohort design strengthens the message because the analysis drew from several large, real-world U.S. datasets rather than a single referral population. Still, the work remains anchored to association, not direct mechanistic experimentation. The data identify who carries risk and how much of the disease burden is statistically attributable to each variant class; they do not yet show the precise myocardial pathway by which CD36 deficiency produces dilated cardiomyopathy in every carrier. Even so, the pattern is clinically actionable now because it refines which genes deserve attention when evaluating cardiomyopathy in individuals of African ancestry.
A final and unavoidable implication is that genomic medicine will continue to underperform unless more ancestral diversity is built into discovery and validation cohorts. In this case, representation did more than improve equity in sampling. It changed the genetic map itself.
The study leaves one practical question open: how should screening panels, variant interpretation pipelines, and family-based testing strategies be recalibrated now that CD36 Y325* has emerged as a major contributor to dilated cardiomyopathy burden in African ancestry populations?