PPP1R13L-Related Cardiomyopathy Stability Following IL1 Inhibition

Variants in PPP1R13L are associated with severe childhood-onset cardiomyopathy resulting in rapid progression to death or cardiac transplantation. PPP1R13L is proposed to encode a protein that limits the transcriptional activity of the NFkappaB pathway leading to elevated IL-1, IL-6, and TNF-alpha production in murine models. Optimal medical management for PPP1R13L-related cardiomyopathy is unknown. Here we report usage of a targeted anti-IL-1 immuno-modulatory therapy resulting in cardiac stabilization in a pediatric patient with congenital cardiomyopathy secondary to PPP1R13L variants. A 4-year-old boy presented acutely with fever in the setting of persistent abdominal pain, vomiting, fatigue, and decreased appetite for two months following a mild COVID-19 related illness. Echocardiogram revealed severely depressed biventricular systolic function with an ejection fraction of 30%. Due to acute decompensated heart failure symptoms with hemodynamic instability, he was intubated and placed on continuous inotropic infusions with aggressive diuresis. Cardiac MRI demonstrated extensive subepicardial to near transmural fibrosis by late gadolinium enhancement in right and left ventricles. An implantable cardioverter-defibrillator (ICD) was placed due to frequent runs of polymorphic non-sustained ventricular tachycardia. Testing for viral pathogens was positive for rhino/enterovirus. Initial genetic testing was non-diagnostic (82-gene cardiomyopathy panel) but given the patient’s significant presentation whole genome sequencing was pursued that showed two separate PPP1R13L variants in trans (c.2167A>C,p.T723P and c.2179_2183del,p. G727Hfs*25, NM_006663.4). Patient serum cytokine testing revealed elevations in IL-10 (4.7 pg/mL) and IL-1beta (20.9 pg/mL). Given the patient’s tenuous circumstances and concern for continued progression of his cardiac disease, a trial of IL-1 inhibition via anakinra dosed at 3 mg/kg or 45 mg daily was initiated following hospital discharge. With approximately 6 months of therapy, the patient’s cardiac function is stable with normalization of IL-10 and IL-1beta serum levels. Notably, the ventricular arrhythmia decreased after initiation of anakinra with no ICD shocks given. Therapy overall has been well tolerated without infectious concerns. In patients with PPP1R13L-related cardiomyopathy, immuno-modulatory therapies should be considered in an attempt to slow cardiac disease progression.