CD36 variant carries a larger share of dilated cardiomyopathy burden than TTN in African ancestry cohorts
A common nonsense variant in CD36 accounted for a larger share of dilated cardiomyopathy burden among individuals of African ancestry than the best-established monogenic cause of the disease, TTN truncating variants. In four large US cohorts, the ancestry-specific signal was not subtle: CD36 carrier status was common enough, and its associated risk strong enough, to exceed TTN at the population level even though TTN still carried the larger per-person odds ratio.
The genetic signal extended beyond rare Mendelian causes
The multicohort study pooled exome or genome sequence data and case status from the All of Us Research Program, Million Veteran Program, Penn Medicine Biobank, and the DCM Precision Medicine Study. Across 82,623 individuals of predominantly African ancestry, the mean age was 53.4 years, 47,124 participants were male, and 1,316 had DCM. This is the sort of cohort size needed to separate a rare, high-penetrance variant from a more frequent ancestry-linked risk allele with a lower individual effect but wider population reach.
Homozygous carriers of the CD36 Y325* risk allele had markedly higher odds of DCM, with an odds ratio of 4.8. Heterozygous carriers also faced increased risk, with an odds ratio of 1.4. For comparison, TTN truncating variants were associated with an odds ratio of 8.5 in participants of African ancestry. The difference between these estimates matters biologically and clinically: TTN remains the stronger single-gene hit for an individual carrier, while CD36 appears to exert a broader effect across the population because the variant is more common and not confined to a small number of families.
A single common allele can shape disease burden more than a rare high-penetrance mutation when it is carried by enough people.
Case counts made the burden visible at the bedside and in the population
Among the 1,316 DCM cases of African ancestry, 33 individuals, or 2.5%, were homozygous for CD36 Y325*, 56 individuals, or 4.3%, carried TTN truncating variants, and 16 individuals, or 1.2%, had pathogenic or likely pathogenic variants in other high-confidence DCM genes. Those numbers give the clearest view of why this variant matters beyond the usual Mendelian framework. TTN truncation carried the biggest per-person risk estimate, but CD36 produced a larger population attributable fraction once both heterozygous and homozygous carriers were counted.
The population attributable fraction for CD36 was 9.0%, including 6.2% from heterozygous carriers and 2.8% from homozygous carriers. TTN truncating variants had a population attributable fraction of 3.7%. In practical terms, a clinician who only thinks in terms of rare familial cardiomyopathy genes will miss an ancestry-linked risk architecture that is broader, more common, and likely more relevant to the overall burden of disease in communities of African ancestry.
Why CD36 may matter mechanistically in dilated cardiomyopathy
CD36 encodes a membrane glycoprotein involved in fatty acid uptake and cellular lipid handling, functions that are especially relevant in the energetically demanding myocardium. A nonsense variant that disrupts this pathway offers a plausible route to myocardial vulnerability, particularly if chronic impairment of substrate utilization alters energetic reserve, stresses myocytes, or amplifies remodeling over time. DCM is not simply a disease of isolated gene failure; it is a final common pathway in which inherited susceptibility intersects with hemodynamic stress, metabolic strain, and environmental exposures. A common functional variant in a metabolic transporter fits that model well.
The clinical meaning is sharper because the variant is enriched among individuals of African ancestry. Genetics does not distribute disease risk evenly across populations, and the burden here reflects both biology and representation. When ancestry-specific variants are absent from the center of genomic discovery efforts, their contribution can be mistaken for unexplained disease, leaving both risk prediction and family counseling incomplete.
TTN still leads for effect size, but not for total burden
TTN truncating variants remain the most established monogenic driver of DCM and still showed the strongest association per carrier in this analysis. The study does not diminish that role. It does, however, recast the hierarchy of genetic importance in African ancestry cohorts by showing that a common CD36 variant may contribute more disease overall than TTN truncation, despite a lower individual-level odds ratio. That distinction changes how genetic screening strategies should be framed in diverse populations, especially when clinicians are considering which variants explain disease prevalence rather than only which variants are most penetrant.
The findings also expose a broader problem in cardiovascular genomics: the most clinically visible mutation is not always the one responsible for the greatest share of cases. Rare high-impact variants dominate textbooks, but common ancestry-linked alleles can drive a larger fraction of disease in real-world populations.
Representation in genomic medicine now carries direct clinical consequences
The study’s strongest message is not simply that CD36 deserves attention. It is that genomic medicine cannot assume the genetic architecture of DCM is interchangeable across ancestry groups. The four-cohort design, drawn from contemporary US biobank and precision medicine resources, gave the analysis enough breadth to compare CD36 with TTN and other established DCM genes in the same framework. That design is especially important because it moves the question from isolated family studies to population-scale attribution.
For clinicians, the implications are immediate in concept even if not yet fully operationalized in routine practice. Genetic evaluation of DCM in individuals of African ancestry may need to account for CD36 Y325* alongside the more familiar sarcomeric and cytoskeletal genes. For investigators, the result is a reminder that ancestry-aware reference datasets are not optional. They are necessary for determining which variants truly explain disease burden and which are merely better known because they were studied first.
The remaining gaps are functional and clinical, not statistical
This study establishes association and population burden, not a treatment pathway. It does not show whether knowledge of CD36 carrier status changes prognosis, guides therapy, or should alter screening in asymptomatic relatives. It also does not replace the need for functional work to determine how the nonsense variant perturbs myocardial metabolism and whether other environmental or genetic factors modify penetrance. Still, the central finding stands on its own: in four US cohorts, an ancestry-specific CD36 variant contributed more to DCM burden among individuals of African ancestry than the canonical TTN truncating variants that usually define the genetic conversation around this disease.