PLN (Phospholamban)

Details

PLN encodes phospholamban, a small membrane protein in the sarcoplasmic reticulum (SR) that regulates the SR Ca²⁺-ATPase (SERCA2a). Pathogenic PLN variants impair calcium cycling in cardiomyocytes, causing arrhythmogenic cardiomyopathy with predominantly left ventricular involvement. The R14del (p.Arg14del) variant is a founder mutation with notably high risk for both malignant ventricular arrhythmias and end-stage heart failure.

Key Facts

• Variant type: Missense, nonsense, and deletion variants; predominantly p.R14del (founder variant). P.R14del accounts for 12% of Dutch ARVC patients and ~1% of US ARVC patients. Also reported in Spain, Germany, Greece, Canada, and Norway. (sources/acm-hrs-2019)

• ECG signature: Low-voltage ECG is a characteristic feature of PLN-related ACM (also seen with desmosomal variants); helps identify this etiology among ACM cases. (sources/acm-hrs-2019)

• Risk stratification: In a Dutch cohort of 403 PLN R14del patients, independent predictors of malignant arrhythmia included: LVEF <45% and NSVT or sustained VT. Exercise-related arrhythmias occur disproportionately in PLN R14del carriers — similar to ARVC — though athletic history does not appear to predict overall penetrance in this group. (sources/acm-hrs-2019)

• ICD recommendations:

  • COR IIa, LOE B-NR: ICD is reasonable in PLN cardiomyopathy with LVEF <45% or NSVT. (sources/acm-hrs-2019)

• Heart failure risk: PLN R14del carriers are at high risk for end-stage HF (requiring transplantation) in addition to SCD — distinguishing PLN from many other ACM genes where arrhythmia risk predominates.

• Disease category: Calcium handling defect; PLN gain-of-function impairs SERCA2a → intracellular Ca²⁺ dysregulation → impaired relaxation, arrhythmogenesis, and cardiomyopathy.

• Exercise restriction: Ventricular arrhythmias occur disproportionately during exercise in PLN R14del carriers; exercise restriction is reasonable but less definitively established than in PKP2-ARVC. (sources/acm-hrs-2019)

• NDLVC classification: Per ESC 2023, PLN-related disease with non-dilated LV and non-ischaemic scar/dysfunction is classified as NDLVC. PLN is listed as a high-risk genotype for SCD in NDLVC regardless of LVEF. (sources/esc-cmp-2023)

• Gene-specific risk calculator: A PLN p.Arg14del variant-specific risk calculator is available: https://plnriskcalculator.shinyapps.io/final_shiny — should be used to guide primary prevention ICD decisions in PLN R14del patients. (sources/esc-cmp-2023)

• Ring-like/subepicardial LGE: Characteristic CMR LGE pattern for PLN variants in NDLVC (along with DSP and FLNC). (sources/esc-cmp-2023)

• ARVC overlap: PLN is also listed as an ARVC-associated gene in Table 5 of ESC 2023 (ARVC: autosomal dominant inheritance). (sources/esc-cmp-2023)

• VA meta-analysis (DCM, n=11,451): PLN mutations significantly associated with sustained VA in DCM in a genotype meta-analysis (Kayvanpour 2017) referenced by Sammani 2020. PLN is one of three key gene variants (with LMNA and FLNC) specifically highlighted as predictors in DCM for which individualized treatment strategies are warranted. Mechanism: PLN impairs SERCA2a → Ca²⁺ dysregulation → DADs/EADs → arrhythmogenicity. (sources/VA-DCM-Sammani-2020)

• Muller 2025 — PLN-p.Arg14del genotype-specific review: Dutch founder variant with mixed arrhythmogenic + heart failure phenotype. Exercise does NOT influence penetrance, VA, or HF events — unique among ACM genes (contrasts sharply with PKP2/TMEM43). Male sex is NOT a risk factor — also unique among ACM genes. Micro voltages and precordial TWI on ECG. High arrhythmic risk; relatively high risk of biventricular cardiomyopathy and end-stage HF requiring transplantation. (sources/ACM-Genotype-Mx-JCE-2024, rating: high)

• PLN risk calculator (Verstraelen 2021): Gene-specific VA risk calculator usable in PLN-p.Arg14del carriers irrespective of clinical phenotype (i.e., applicable to gene-positive/phenotype-negative relatives). This contrasts with the ARVC risk calculator which requires definite ARVC diagnosis. Long-term reliability confirmed (van der Heide 2024). (sources/ACM-Genotype-Mx-JCE-2024)

• Exercise in PLN: Exercise restriction may not be advised in mild-to-moderately active PLN carriers without known VA risk factors — a gene-specific departure from standard ACM exercise guidance. Caution still warranted in those with known VA risk factors. (sources/ACM-Genotype-Mx-JCE-2024)

Gene Therapy

• PULSE (NCT07241104) is the first human trial. A subcutaneous siRNA targeting the p.R14del PLN transcript in adults with the mutation and LVEF ≤45%: Phase I, three single-ascending-dose and three multiple-ascending-dose cohorts, with treatment-emergent adverse events as the primary endpoint and PLN mRNA in endomyocardial biopsy as a secondary one. It is the only re-dosable, non-viral programme among the five arrhythmia gene-therapy trials now running. (sources/gene-therapy-arrhythmia-cjca-2026, rating: high)
• Why silencing rather than replacement works here: suppressing ≥50% of phospholamban activity appears to be tolerated, so reducing the mutant transcript is a viable strategy in a way that replacement would not be for a toxic-gain or dominant-negative protein.
• ASO knockdown tripled survival in mice. A PLN ASO conjugated to palmitic acid, given at 3 weeks to homozygous p.R14del mice, cut PLN protein by 50%; treated animals were protected from cardiomyopathy at 7 weeks, had partial restoration of the characteristic low ECG voltage, and had median survival extended from 7.5 to 24 weeks and beyond. (sources/gene-therapy-arrhythmia-cjca-2026)
• CRISPR knockout of the mutant allele in heterozygous p.R14del mice reduced its expression by 15–20% and improved ventricular function with reduced arrhythmia vulnerability.
• DWORF overexpression — a micropeptide that counters phospholamban and activates SERCA2a — extended survival of homozygous p.R14del mice from ~7–8 weeks to ~17–20 weeks. Notably, this effect did not appear to work through SERCA2a activation but through reducing aberrant SR/ER cluster formation, which is now the leading mechanistic hypothesis for the disease (see Contradictions). (sources/gene-therapy-arrhythmia-cjca-2026)

Contradictions / Open Questions

• Is p.R14del a gain or a loss of phospholamban function? This page has described PLN disease as gain-of-function — constitutive SERCA2a inhibition — and that model is now in question. More recent evidence suggests the inhibitory capacity of p.R14del phospholamban may actually be impaired, with cardiomyopathy arising instead from aberrant SR and endoplasmic reticulum cluster formation. The question is not academic: if the protein is toxic by misfolding rather than by over-inhibiting SERCA2a, then silencing (the PULSE strategy) is rational and SERCA2a activation is not. DWORF's benefit occurring without any measurable change in SERCA2a activity supports the misfolding model. (sources/gene-therapy-arrhythmia-cjca-2026, rating: high)
• PLN R14del risk calculator — Dutch cohort derivation, limited generalizability: The PLN p.Arg14del–specific risk calculator was derived and validated in Dutch/European cohorts, where the R14del is a founder variant (12% of Dutch ARVC patients). Its applicability in non-Dutch populations (where R14del is rare and other PLN variants may have different risk profiles) is uncertain. Using the Dutch calculator in a North American or Asian PLN carrier without R14del may not produce calibrated risk estimates. (sources/esc-cmp-2023)
• Exercise restriction in PLN R14del — less established than in PKP2-ARVC: Exercise-related arrhythmias occur disproportionately in PLN R14del carriers, but exercise restriction is described as "reasonable" rather than Class I in the context of PLN specifically. The guideline explicitly notes that athletic history does not appear to predict overall penetrance in this group. This creates a paradox: exercise increases arrhythmic risk acutely, but pre-existing athletic activity does not predict penetrance, leaving patients and physicians without a clear framework for activity modification. (sources/acm-hrs-2019)
• Dual classification in ACM/ARVC and NDLVC — management pathway ambiguity: PLN is listed as an ARVC-associated gene (Table 5, ESC 2023) with autosomal dominant inheritance and also as a high-risk NDLVC genotype. Patients with PLN-related disease may meet criteria for either classification depending on imaging phenotype at presentation. The management implications overlap substantially but are framed within two different diagnostic pathways with different monitoring recommendations. (sources/esc-cmp-2023, sources/acm-hrs-2019)

Connections

• Related to entities/ALVC
• Related to concepts/Arrhythmogenic-Cardiomyopathy
• Related to concepts/Sudden-Cardiac-Death
• Related to concepts/Cascade-Family-Screening
• Related to entities/NDLVC
• Related to concepts/Late-Gadolinium-Enhancement
• Related to concepts/VA-Risk-Stratification-DCM
• Related to sources/ACM-Genotype-Mx-JCE-2024
• Related to concepts/Gene-Silencing-Therapy — the ASO and siRNA routes
• Related to concepts/Gene-Therapy-Transduction-Threshold — why partial knockdown can be therapeutic

Sources

• sources/gene-therapy-arrhythmia-cjca-2026
• sources/ACM-Genotype-Mx-JCE-2024
• sources/VA-DCM-Sammani-2020
• sources/acm-hrs-2019
• sources/esc-cmp-2023