| Entity | Inheritance / variant mechanism | Typical onset / phenotype | Key example variants | Evidence caveat |
|---|---|---|---|---|
| **DCM1FF (OMIM 613286)** | Autosomal dominant; heterozygous **TNNI3** variants, including function-altering missense variants and reported truncation-associated haploinsufficiency | Variable-onset dilated cardiomyopathy with ventricular dilation and systolic dysfunction; penetrance and expressivity can vary within and between families | p.Arg98Ter (p.98trunc); p.Glu182Lys and p.Glu184Lys have also been listed with DCM | Very rare, with uneven variant-level evidence. Pathogenicity requires ACMG/AMP assessment using population frequency, segregation, and functional evidence. Must not be conflated with recessive infantile DCM. |
| **DCM2A (OMIM 611880)** | Autosomal recessive; biallelic **TNNI3** loss-of-function variants causing markedly reduced or absent cardiac troponin I | Severe neonatal or infantile DCM, often presenting in the first year with ventricular dilation, very low LVEF, rapidly progressive heart failure, transplantation, or death | Homozygous c.292C>T (p.Arg98Ter); c.204del (p.Arg69AlafsTer8); c.150G>A (p.Lys50=), causing abnormal splicing; contiguous deletion involving **TNNI3** | Strongest loss-of-function evidence concerns biallelic disease. Heterozygous carrier parents may be unaffected; recessive cases must not be classified as autosomal-dominant DCM1FF. |
| **Other TNNI3 cardiomyopathies: HCM, RCM, and LVNC** | Usually autosomal-dominant missense disease in HCM or RCM through gain-of-function or dominant-negative effects; recessive missense and splice variants also occur; mechanism is variant-dependent | HCM and RCM may begin in childhood or adulthood; pediatric RCM can progress rapidly and have poor prognosis. LVNC has been reported with biallelic splice variation. Intermediate and overlapping phenotypes occur. | HCM: p.Arg21Cys and p.Arg79Cys; RCM: p.Arg192Cys and homozygous p.Asp196His; LVNC: homozygous c.24+2T>A | The same gene can cause distinct phenotypes. HCM, RCM, or LVNC evidence does not automatically establish DCM1FF causality; some reported alleles remain VUS or show low penetrance. |


*Table: This table separates autosomal-dominant DCM1FF from biallelic TNNI3 loss-of-function DCM2A and other TNNI3-associated cardiomyopathies. Evidence comes from human cases, myocardial functional studies, and reviews. (pqac-00000001, pqac-00000002, pqac-00000003, pqac-00000004, pqac-00000005, pqac-00000006, pqac-00000007)*