Dilated Cardiomyopathy 2B (CMD2B / GATAD1-related DCM)

Disease knowledge-base research report MONDO:0013848 · OMIM 614672 · Gene: GATAD1 (7q21.2) Date: 2026-09-25

Evidence-base caveat. CMD2B is an ultra-rare Mendelian cardiomyopathy. The human clinical description rests essentially on a single consanguineous kindred (Theis et al. 2011, P21965549). Almost all mechanistic detail comes from in vitro biochemistry (P38605029 P26841866) and model organisms (zebrafish P28955713; mouse P39641830 P39626862). Where a statement is generic to dilated cardiomyopathy (DCM) as a class rather than specific to CMD2B, this is flagged. Source type is labeled throughout as [human clinical], [in vitro], [model organism], or [computational/inferred].


1. Disease Information

Overview. Dilated Cardiomyopathy 2B (CMD2B) is a rare autosomal recessive form of familial dilated cardiomyopathy caused by biallelic mutation of GATAD1 (GATA zinc-finger domain-containing protein 1). Like other DCMs it is defined by left-ventricular (LV) dilation and systolic dysfunction (reduced ejection fraction) not explained by abnormal loading conditions or coronary disease, presenting clinically as heart failure and predisposing to arrhythmia. CMD2B is distinguished from the far more common autosomal-dominant DCMs by its recessive transmission with clinically silent heterozygous carriers [human clinical, P21965549].

Key identifiers. | Resource | ID | |---|---| | Mondo | MONDO:0013848 (dilated cardiomyopathy 2B) | | OMIM (phenotype) | 614672 — CARDIOMYOPATHY, DILATED, 2B; CMD2B | | OMIM (gene) | 614518 — GATAD1 | | HGNC | HGNC:29941 (GATAD1) | | NCBI Gene | 57798 | | Ensembl | ENSG00000157014 | | UniProt | Q8WUU5 (GATD1_HUMAN) | | RefSeq | NM_021167.5 / NP_066990.3 (GATAD1, 249 aa); LRG_746 | | Founder variant | NM_021167.5:c.304T>C (p.Ser102Pro); ClinVar VCV31656; rs387907188 | | ICD-10 | I42.0 (Dilated cardiomyopathy) | | ICD-11 | BC43.0 (Dilated cardiomyopathy) | | MeSH | D002311 (Cardiomyopathy, Dilated) | | Orphanet | within ORPHA:154 (Familial isolated dilated cardiomyopathy) — no distinct subtype code |

Synonyms / alternative names. CMD2B; Cardiomyopathy, dilated, 2B; GATAD1-related/GATAD1-associated dilated cardiomyopathy; autosomal recessive dilated cardiomyopathy (GATAD1 type).

Data source type. Disease-level aggregated resources (OMIM/Mondo) plus individual-patient data from one published family; no EHR/registry-scale cohort exists for this specific subtype.


2. Etiology

Primary causal factor — genetic. CMD2B is a monogenic, biallelic disorder. Disease requires two loss-/alteration-of-function alleles of GATAD1. In the index family a homozygous missense mutation altering the conserved serine-102 residue (reported as p.Ser102Pro) segregated with recessive DCM; it was absent from HapMap, 1000 Genomes and 474 ethnically matched controls [human clinical, P21965549].

"altered a conserved residue of GATAD1 … Thirteen relatives were heterozygous mutation carriers with no evidence of myocardial disease, even at advanced ages." (P21965549)

Genetic risk factors. - Causal variant: homozygous GATAD1 p.Ser102Pro (7q21.2). Because unaffected heterozygotes exist, a single allele is insufficient (recessive). - Consanguinity is a major predisposing structural factor — the founding couple were first cousins, and homozygosity mapping exploited runs of homozygosity [human clinical, P21965549]. - Modifier genes: none specifically identified for CMD2B (data unavailable).

Environmental / lifestyle risk factors. No CMD2B-specific environmental trigger is established. For DCM broadly, alcohol, cardiotoxic chemotherapy (anthracyclines), myocarditis/viral infection, peripartum state, thyroid disease and tachyarrhythmia are recognized acquired causes/"second hits"; these may act as gene–environment modifiers superimposed on genetic susceptibility [DCM-class; P42537484 notes "second-hit" genetic contributions]. Not demonstrated for GATAD1 specifically.

Protective factors. No genetic or environmental protective factor is described for CMD2B (data unavailable). By inference, absence of a second pathogenic allele is "protective" (heterozygotes unaffected).

Gene–environment interactions. Mouse data suggest GATAD1 becomes functionally important under stress: cardiac Gatad1 loss worsens ischemia–reperfusion injury and abolishes sphingosylphosphorylcholine cardioprotection [model organism, P39626862], implying environmental/metabolic stressors may unmask or aggravate GATAD1-deficient myocardium — inferred, not shown in patients.


3. Phenotypes

All descriptions derive from the single reported kindred [human clinical, P21965549] plus generic DCM knowledge.

Phenotype Type HPO term Onset / severity / course Frequency
Dilated cardiomyopathy clinical/imaging sign HP:0001644 Adult-onset, progressive Core, defining (homozygotes)
Left ventricular enlargement / dilatation imaging sign HP:0001640 (cardiomegaly), HP:0001712 (LV hypertrophy—N/A) Adult; may be isolated/milder Present incl. an "intermediate" male
Reduced LV ejection fraction / systolic dysfunction imaging/functional HP:0001635 (congestive heart failure), HP:0005162 (abnormal LV function) Progressive Core
Congestive heart failure (dyspnea, fatigue, edema) symptoms HP:0001635 Adult, progressive Expected in overt cases
Arrhythmia / risk of sudden death sign HP:0011675 (arrhythmia) Variable DCM-class risk; not detailed for CMD2B
Abnormal cardiomyocyte nuclear morphology pathology (biopsy) (cellular) — Seen in proband myocardium

Phenotype characteristics. Age of onset: adult-onset (HP:0003581) with age-dependent penetrance; the affected sisters were adults, and a brother had milder "idiopathic LV enlargement," illustrating variable expressivity (HP:0003828). Severity ranges from isolated LV dilatation to overt DCM/heart failure. Course: chronic, progressive.

Quality-of-life impact. No CMD2B-specific QoL data. For symptomatic DCM/heart failure generally, health-related QoL is substantially reduced (dyspnea, exertional limitation, hospitalizations); disease-specific instruments include the Kansas City Cardiomyopathy Questionnaire and Minnesota Living with Heart Failure Questionnaire (data unavailable for this subtype).


4. Genetic / Molecular Information

Causal gene. GATAD1 — GATA zinc-finger domain-containing protein 1; 7q21.2; HGNC:29941; NCBI Gene 57798; OMIM 614518; UniProt Q8WUU5. Encodes a nuclear protein containing a GATA-type zinc finger that functions as a reader of H3K4me3 and a subunit of a histone-modifying chromatin complex [in vitro, P26841866; 39641830].

Pathogenic variant (founder allele of the index family). - HGVS: GATAD1 NM_021167.5:c.304T>C, protein p.Ser102Pro (LRG_746; UniProt Q8WUU5:p.Ser102Pro); genomic chr7:g.92078120T>C (GRCh38) [database-verified, ClinVar]. - Identifiers: ClinVar Variation ID 31656; dbSNP rs387907188. - Type/class: single-nucleotide missense; germline; homozygous in affected individuals [human clinical, P21965549]. - Classification: Pathogenic in ClinVar for "Dilated cardiomyopathy 2B" (review status: no assertion criteria provided — 1-star). Ser102 is N-terminal to the GATA-type zinc finger, within the intrinsically disordered region bearing the 14-3-3 phospho-motif. In-silico: CADD 21.8, PolyPhen-2 probably damaging; SIFT tolerated (mildly discordant). - Allele frequency: absent from gnomAD (genomes and exomes) and absent from HapMap, 1000 Genomes and 474 matched controls [PMID 21965549] — private/ ultra-rare. - Broader GATAD1 landscape: most GATAD1 ClinVar entries are VUS or likely benign; only rare truncating variants are (likely) pathogenic. GATAD1 is frequently reported as VUS on cardiomyopathy panels (P38664609 P40200748) — caution for novel variants. - Functional consequence: the mutation destroys a phospho-serine 14-3-3 docking site, altering GATAD1 nucleocytoplasmic transport and producing aberrant subcellular localization and abnormal nuclear morphology [in vitro, P38605029; human IHC, P21965549]. Mechanistically this is not a simple null (see §6): a cardiomyocyte Gatad1 knockout mouse is healthy [PMID 39641830], suggesting an aberrant-function/mislocalization effect rather than pure loss-of-function.

Modifier genes / epigenetic / chromosomal. No CMD2B-specific modifier genes, constitutional epigenetic marks, or chromosomal abnormalities reported (data unavailable). Note GATAD1 itself acts within an epigenetic (histone-modifying) complex — see §6.


5. Environmental Information

No environmental factor, occupational exposure, toxin, or infectious agent is implicated in the causation of CMD2B specifically (it is a monogenic disease; data unavailable). Generic DCM environmental contributors (alcohol, anthracyclines, viral myocarditis, peripartum state) may act as aggravating second hits on a genetically susceptible myocardium but are unproven for GATAD1. No infectious agent applies.


6. Mechanism / Pathophysiology

Ordered causal chain (initiating lesion → clinical manifestation)

  1. Homozygous GATAD1 p.Ser102Pro substitutes proline for a serine phosphorylation site → abolishes a phospho-Ser 14-3-3 docking motif [in vitro, P38605029].
  2. Loss of 14-3-3 binding → dysregulated masking of a nuclear localization signal → altered nucleocytoplasmic transport / mislocalization of GATAD1 [in vitro, P38605029]; observed as aberrant subcellular localization and abnormal nuclear morphology in patient LV myocytes [human clinical, P21965549].
  3. Mislocalized/altered GATAD1 → disrupted incorporation/function within the EMSY–KDM5A(H3K4me3 demethylase)–SIN3B/HDAC histone-modifying complex [in vitro, P26841866] → altered H3K4me3-linked transcriptional regulation at target promoters [inferred].
  4. Branch A (transcriptional/chromatin): dysregulated cardiac gene expression programs → impaired maintenance of normal cardiomyocyte structure/function → contractile dysfunction [inferred from P21965549 P26841866].
  5. Branch B (metabolic): as a transcription factor GATAD1 normally represses fatty-acid-oxidation genes (Acaa2, Acadm) and promotes glucose oxidation; its dysfunction shifts myocardial substrate metabolism and lowers stress tolerance (larger infarcts / worse function under ischemia–reperfusion) [model organism, P39626862].
  6. Converging branches → cardiomyocyte dysfunction → LV chamber dilation and systolic dysfunction (reduced EF) [human clinical, P21965549].
  7. → congestive heart failure, and (DCM-class) predisposition to ventricular arrhythmia / sudden cardiac death → end-stage disease potentially requiring transplantation.

Steps 1–2 are experimentally demonstrated; step 3 (complex membership) is demonstrated biochemically but not in heart tissue; steps 4–7 are inferred from correlative human pathology and model-organism data. A key unresolved point: cardiomyocyte-specific Gatad1 deletion does not cause disease in mouse (P39641830), so the pathogenic mechanism likely involves an aberrant/ dominant-negative-like effect of the mislocalized mutant and/or non-cell- autonomous or developmental requirements — not simple loss-of-function.

Detail by category


7. Anatomical Structures Affected


8. Temporal Development


9. Inheritance and Population


10. Diagnostics

Cardiac phenotyping (DCM-class, applied to CMD2B). - Imaging: transthoracic echocardiography (LV dilation, reduced LVEF) — first-line; cardiac MRI (chamber volumes, function, late-gadolinium fibrosis) [DCM-class; stress echo relevance P18579481]. LOINC/RadLex apply. - ECG / Holter: arrhythmia and conduction assessment. - Biomarkers: NT-proBNP/BNP (heart-failure severity); troponin as adjunct (non-specific). No CMD2B-specific circulating biomarker. - Endomyocardial biopsy: not routine; in the proband it revealed aberrant cardiomyocyte nuclear morphology / GATAD1 mislocalization [PMID 21965549].

Genetic testing (definitive for subtype). - Recommended approach: NGS cardiomyopathy multigene panel (GATAD1 is included on modern panels, P38664609) or whole-exome/genome sequencing; the original diagnosis used homozygosity mapping + exome sequencing in a consanguineous pedigree [PMID 21965549]. - Confirm biallelic GATAD1 variants (homozygous or compound heterozygous) with segregation; classify per ACMG/AMP (many GATAD1 variants are currently VUS). - CMA/karyotype/FISH/mtDNA/repeat-expansion testing: not indicated for this single-gene point-mutation disorder.

Clinical criteria / differential diagnosis. Diagnose DCM by LV dilation + systolic dysfunction after excluding ischemic, valvular, hypertensive, toxic (alcohol/anthracycline), infiltrative, peripartum and myocarditic causes. Differential: other genetic DCMs (TTN, LMNA, RBM20, FLNC, DES, MYH7), arrhythmogenic and hypertrophic cardiomyopathies. The recessive pattern + consanguinity + GATAD1 genotype distinguishes CMD2B.

Screening. Cascade genetic testing of relatives and echocardiographic surveillance of at-risk biallelic individuals (see §13). Family screening yields ~10% at baseline and ~10% more over 5 years in DCM generally (P39833651).


11. Outcome / Prognosis


12. Treatment

No gene-specific or curative therapy exists for CMD2B. Management follows guideline-directed medical therapy (GDMT) for DCM/heart failure with reduced ejection fraction:


13. Prevention


14. Other Species / Natural Disease


15. Model Organisms

Zebrafish (Danio rerio, Taxon 7955) — supportive positive model. Yang, Shah, Olson & Xu 2016 (P28955713) generated an adult zebrafish model of the gatad1 homologue specifically to overcome age-dependent penetrance and validate GATAD1 as a bona fide DCM gene in a higher-throughput vertebrate.

"we generated an adult zebrafish model, which is a simpler vertebrate model with higher throughput than rodents." (P28955713) - Model type: genetic vertebrate; application: validating causality, studying adult-onset cardiomyopathy mechanisms.

Mouse (Mus musculus, Taxon 10090) — informative negative / limitation. Pang et al. 2024 (P39641830) made a cardiomyocyte-specific Gatad1 knockout (cKO). It showed normal cardiac function to 18 months, normal nuclear shape (unlike patients), and normal response to pressure overload (TAC).

"deletion of Gatad1 in cardiomyocytes does not induce cardiomyopathy during aging or affect the response to pressure-overload stress in mice." (P39641830) - Interpretation/limitation: pure cardiomyocyte loss-of-function is insufficient in mouse → argues the human p.Ser102Pro acts via aberrant function/mislocalization or non-cardiomyocyte/developmental requirements; a knock-in of the p.Ser102Pro allele would be the more faithful (still-needed) model.

Additional mouse model (metabolic). A myocardium-specific Gatad1 cKO was used to show GATAD1 controls the fatty-acid/glucose oxidation balance and modulates ischemia–reperfusion injury (P39626862).

In vitro / cellular systems. Peptide-interaction proteomics and structural studies of the Ser102 phosphosite–14-3-3 interaction (P38605029); biochemical characterization of the EMSY/KDM5A/SIN3B complex (P26841866). No iPSC- cardiomyocyte CMD2B model is yet reported (opportunity/gap).

Resources: MGI (mouse Gatad1), ZFIN (zebrafish gatad1), Alliance of Genome Resources.


Summary of Supported vs. Refuted / Open Hypotheses

Limitations

Human evidence rests on one consanguineous kindred; mechanism is pieced together from in-vitro and cross-species models with a notable mouse/zebrafish discordance. Epidemiologic, prognostic, and treatment-response data specific to CMD2B do not exist and were substituted with clearly-labeled DCM-class information.

Key References (PMIDs)