Cardiogenetics 2019; volume 9:8181 FLNC missense variants than 2 according to current echocardio- in familial noncompaction graphic criteria, or 2.3 on CMR.1,2 Correspondence: Jaap I. van Waning, Approximately 10% of patients diagnosed Department of Clinical Genetics, EE 2038, cardiomyopathy with NCCM have concurrent congenital Erasmus MC, POB 2040, 3000CA Rotterdam, heart defects (CHD).3,4 the Netherlands. Tel.: +3107038388 - Fax: +3107043072. Jaap I. van Waning,1 In 30-40% of cases diagnosed with E-mail: [email protected] Yvonne M. Hoedemaekers,2 NCCM a pathogenic variant can be identi- 2,3 4 Wouter P. te Rijdt, Arne I. Jpma, fied. Around 80% of these pathogenic vari- Acknowledgements: JVW was supported by a Daphne Heijsman,4 Kadir Caliskan,5 ants involve the same sarcomere genes, that grant from the Jaap Schouten Foundation. Elke S. Hoendermis,6 are the major causes for hypertrophic car- WPTR was supported by a Young Talent Program (CVON PREDICT) grant 2017T001 Tineke P. Willems,7 diomyopathy (HCM) and dilated cardiomy- - Dutch Heart Foundation. 8 opathy (DCM), in particular MYH7, Arthur van den Wijngaard, 5,6 3 MYBPC3 and TTN. Filamin C (FLNC) Albert Suurmeijer, Conflict of interest: the authors declare no plays a central role in muscle functioning Marjon A. van Slegtenhorst,1 potential conflict of interest. by maintaining the structural integrity of the Jan D.H. Jongbloed,2 muscle fibers. Pathogenic variants in FLNC Received for publication: 20 March 2019. Danielle F. Majoor-Krakauer,1 2 were found to be associated with a wide Revision received: 29 July 2019. Paul A. van der Zwaag spectrum of myopathies ranging from car- Accepted for publication: 17 September 2019. 1Department of Clinical Genetics, diomyopathies to distal skeletal Erasmus Medical Center, Rotterdam; myopathies. Truncating FLNC variants This work is licensed under a Creative Commons Attribution NonCommercial 4.0 2Department of Genetics, University of were previously associated with dilated car- 7-9 License (CC BY-NC 4.0). Groningen, University Medical Center diomyopathy and missense variants were Groningen, Groningen; 3Department of identified in familial HCM and restrictive ©Copyright: the Author(s), 2019 Pathology, University of Groningen, cardiomyopathy. FLNC has not been associ- Licensee PAGEPress, Italy University Medical Center Groningen, ated with NCCM or CHD before. onlyCardiogenetics 2019; 9:8181 4 We present two Dutch families where doi:10.4081/cardiogenetics.2019.8181 Groningen; Department of Pathology, familial NCCM with CHD were linked to Erasmus Medical Center, Rotterdam; rare FLNC missense variants. These obser- 5Department of Cardiology, Erasmus vations suggest that the spectrum of clinical Medical Center, Rotterdam; use 6 manifestations of FLNC variants include the anterior mitral valve leaflet (Figure 2A Department of Cardiology, University familial NCCM with CHD. and B). The noncompaction had not been of Groningen, University Medical recognized in the past on echocardiography. Center Groningen, Groningen; Cardiologic screening of an asymptomatic 7 Department of Radiology, University of brother (II:4) at age 54 years showed that he Groningen, University Medical Center Case Reports also had NCCM; with a NC/C ratio of 2.3 Groningen, Groningen; 8Department of on echocardiography and a ratio of 2.9 on Clinical Genetics, Maastricht University Family A CMR. No previous cardiac imaging had Medical Center, Maastricht, the In this family (Figure 1A), a 52-year- been performed. He had elevated CK-levels Netherlands old woman (II:3) was first diagnosed with of 265 U/L without neuromuscular signs. NCCM when she underwent cardiologic Ten years after the diagnosis NCCM he had examination for a suspected perimyocardi- an episode of atrial fibrillation that required tis. Echocardiography showed pericardial electric cardioversion. CMR from the broth- Abstract effusion and normal LV dimensions without er (II:1) and the son (III:1) of the proband LV dysfunction. The LV walls showed were performed at age 57 and 15 years, The majority of familial noncompaction hypertrabeculation with end-systolic non- respectively, showing borderline NC/C cardiomyopathy (NCCM) is explained by compacted/compacted (NC/C) ratio >2. ratios of respectively 2.1 and 2.2 on MRI, pathogenic variants in the sameNon-commercial sarcomeric Electrocardiographically, inferolateral repo- i.e. just below the diagnostic criteria. genes that are associated with hypertrophic larization abnormalities were observed. Proband III-2 did not participate in the fam- (HCM) and dilated (DCM) cardiomyopa- Cardiac magnetic resonance imaging ily screening. thy. Pathogenic variants in the filamin C (CMR) confirmed the diagnosis of NCCM gene (FLNC) have been linked to HCM and with diastolic NC/C ratio >2.3 in the LV Family B DCM. We expand the spectrum of FLNC inferoseptal wall. She had elevated CK lev- In family B (Figure 1B) the diagnosis related cardiomyopathies by presenting two els of 1234 U/L [ref <200U/l]. No signs for NCCM in a 17-year-old boy (III:1) was families with likely pathogenic FLNC vari- neuromuscular disease were detected at made by echocardiography. He was referred ants showing familial segregation of neurologic examination. After seven years because of multiple unexplained episodes NCCM and concurrent coarctation of the of follow-up, she remained cardiologically of syncope. He also had a ventricular septal aorta and/or mitral valve abnormalities. asymptomatic (NYHA class I). defect (VSD) and a mild mitral valve pro- Family screening revealed NCCM in lapse (MVP). CMR revealed partial LV two relatives. A niece (III:3), was diagnosed noncompaction from the apex to midven- Introduction with NCCM at age 21 and had surgery at tricular region with an NC/C ratio of 3.0 Noncompaction cardiomyopathy age seven for coarctation of the aorta (Figure 2C and D). An implantable car- (NCCM) is characterized by excessive tra- (CoA). She fulfilled both the echocardiog- dioverter-defibrillator (ICD) was implanted. beculation of the left ventricle (LV) with a raphy and CMR diagnostic criteria for After 9 years of follow-up, the LV function noncompacted to compacted ratio of more NCCM and had excessive long chordae of remained normal without ICD shocks. CK- [Cardiogenetics 2019; 9:8181] [page 9] Article levels were elevated (419-1188 U/L) in the Segregating synonymous variants and vari- family B (III:1) were stained with hema- absence of neuromuscular signs. His mother ants predicted to be tolerated were exclud- toxylin and eosin as well as Masson’s (II:2) was under cardiologic surveillance ed. In Family A, two candidate genes trichrome. To visualize protein aggregation because she had a VSD, MVP, CoA and a remained after filtering, MYH4 and FLNC, and autophagic activity in cardiomyocytes, bicuspid aortic valve. The CMR showed of which only the last was previously asso- immunohistochemistry for microtubule- that she complied for the diagnostic criteria ciated with cardiomyopathy. A variant in associated protein 1A/1B-light chain 3 for NCCM with a NC/C ratio of 2.4. She FLNC (c.6397C>T, p.(Arg2133Cys), (LC3) was performed, as described previ- had diastolic LV dysfunction, with pre- NM_001458.4, confirmed by sanger ously.16 Light microscopic analysis showed served LV systolic function and underwent sequencing) segregated with the cardiac nonspecific cardiomyopathic changes of multiple cardiac ablations for atrial fibrilla- phenotype of NCCM in the three NCCM myocyte hypertrophy and increased intersti- tion. At age 44 years she experienced severe patients and in the two relatives with bor- tial fibrosis (Figure 3A). The RV did not bradycardia, which necessitated cardiac derline NCCM features. A variant in the show an excessively thickened endocardial resuscitation, resulting from combined fle- same location (p.(Arg2133His)) was previ- layer or hypertrabeculation, or intracellular cainide and metoprolol treatment. A pace- ously reported in a family with HCM and aggregates or autophagic activity (Figure maker was implanted. Her highest CK-level classified as probably pathogenic.15 In fam- 3B). was 1174 U/L. The proband’s brother (III:2) ily B, a novel FLNC variant (c.7177C>T, also suffered multiple episodes of syncope p.(Pro2393Ser)) was identified. The two and was diagnosed with NCCM at age 19, FLNC variants were absent in the Genome with a NC/C ratio of 3.1 on CMR. His high- Aggregation Database (http://gnomad. Discussion and conclusions est CK-level was 294U/l. Proband III-3 was broadinstitute.org), affect highly conserved This is the first report linking FLNC to screened cardiologically and had no signs amino acids, and were predicted to be dele- NCCM in two families with rare FLNC of NCCM on echocardiography. No DNA terious by multiple in silico prediction pro- variants. In these two families the cardiac analysis was performed. grams. No FLNC variants were found in thirteen unrelated NCCM patients without a phenotype included NCCM, NCCM with Genetic testing CHD and without a pathogenic variant in 48 concurrentonly CoA, NCCM with concurrent Diagnostic DNA NGS targeted testing cardiomyopathy genes. VSD and MPV and also a NCCM patient of a panel of 54 cardiomyopathy genes, that with a complex CHD consisting of VSD, did not include FLNC, as presented in Table Histology MVP, CoA and bicuspid aortic valve, and 1, did not reveal a genetic causes for NCCM Right ventricular endomyocardial biop- myocardial dysfunction. These observations in the two index cases. Also single- sy (RVEMB) samples from the probanduse of suggest that missense FLNC variants may nucleotide polymorphism-array DNA test- ing showed no structural DNA changes. Subsequently, whole exome sequencing was performed in the NCCM patients II:1, III:1 and III:3 from family A and III:1, III:2, and II:2 from family B. Patients II-2 from family B was included because we suspect- ed that a causative mutation may underlie a spectrum of cardiac phenotypes. Written informed consent was obtained from all par- ticipating family members. The investiga- tion conforms to the principles outlined in the Declaration of Helsinki.