Beckwith-Wiedemann syndrome (BWS) is characterized by overgrowth and increased risk of embryonic tumors. It results from alterations in genes controlled by imprinting centers H19DMR (Imprinting Center [IC] 1) and KvDMR (IC2). Strategies for diagnostic confirmation include methylation analysis and CDKN1C sequencing. We present a newborn with placentomegaly, hyperinsulinism and adrenal cytomegaly, but no typical external features of BWS. The patient had normal genetic studies in blood. However, adrenal and liver tissues showed hypermethylation of IC1 and hypomethylation of IC2. Microsatellite analysis confirmed mosaic paternal uniparental disomy. This study demonstrates the importance of analyzing additional tissues to reduce underdiagnosis of somatic mosaicism in BWS.

Inherited epidermolysis bullosa (EB) comprises rare heterogeneous disorders characterized by cutaneous and mucosal fragility. Most of the 20 proteins affected have structural functions. Recently, a previously undescribed type of EB simplex (EBS), caused by gain-of-function mutations in KLHL24, encoding KLHL24 has been identified (He et al., 2016He Y. Maier K. Leppert J. Hausser I. Schwieger-Briel A. Weibel L. et al.Monoallelic mutations in the translation initiation codon of KLHL24 cause skin fragility.Am J Hum Genet. 2016; 99: 1395-1404Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar, Lin et al., 2016Lin Z. Li S. Feng C. Yang S. Wang H. Ma D. et al.Stabilizing mutations of KLHL24 ubiquitin ligase cause loss of keratin 14 and human skin fragility.Nat Genet. 2016; 48: 1508-1516Crossref PubMed Scopus (82) Google Scholar). This protein seems to be involved in protein ubiquitination. Patients carrying monoallelic mutations in the translation initiation codon of KLHL24 have a characteristic clinical phenotype, showing skin defects and blistering at birth and unusual stellate scarring, skin fragility, and whorled or macular hyperpigmentation or hypopigmentation in childhood (Figure 1a–e ). Although skin fragility improves by adulthood, nail dystrophy, anetoderma, and hair loss may occur (Figure 1f–h). Given that KLHL24 is widely expressed, we investigated extracutaneous features in a cohort comprising families from Chile, Germany, Italy, Switzerland, and the United States (see Supplementary Material online). Institutional approval for investigations and written informed consent were obtained, and patients gave permission to have their photographs and medical information published. Eighteen patients with EBS-KLHL24 from nine families (nine males, nine females) were examined (Table 1). The mean patient age was 21.7 years, with nine children (2–13 years old) and nine adults (24–46 years old). Patients 1–10 have previously been described (He et al., 2016He Y. Maier K. Leppert J. Hausser I. Schwieger-Briel A. Weibel L. et al.Monoallelic mutations in the translation initiation codon of KLHL24 cause skin fragility.Am J Hum Genet. 2016; 99: 1395-1404Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar), and patients 11–18 are newly reported. Two additional individuals (patients 19 and 20) belong to family 9; they had skin fragility and died of dilated cardiomyopathy (DCM) at the ages of 39 and 54 years. In all examined patients, pathogenic variants in the translation initiation codon of KLHL24 were found (Table 1). Whole-exome sequencing and multigene panel data showed no pathogenic variants in genes known to be associated with DCM (Burke et al., 2016Burke M.A. Cook S.A. Seidman J.G. Seidman C.E. Clinical and mechanistic insights into the genetics of cardiomyopathy.J Am Coll Cardiol. 2016; 68: 2871-2886Crossref PubMed Scopus (176) Google Scholar).Table 1Patient descriptions with genetic, clinical, and laboratory findings1Values in bold exceed reference values.Patient NumberFamily NumberAge in Years (Sex)Country of OriginMutation KLHL24Cardiac Symptoms/Clinical FeaturesCK in U/L (Normal Value)CKMB in ng/ml (Normal Value)Pro-BNP in pg/ml (Normal Value)ECG/Echocardiogram/MRIOther Clinical Features/Symptoms1134 (M)Switzerland-Italyc.[1A>G]None/BP = 105/80 mm Hg237 (<168)32 (<25)1,221 (<120)ECG: Nonspecific changesEcho: Severe biventricular DCM, EF = 27%MRI: Transmural fibrosis, corresponding to the thinned inferior and inferolateral wall of the LVNontransmural mid-wall fibrosis in the septum; the lateral, anterior and septal segments of the LV show nontransmural fibrosisDiffuse fibrosis in the RV.Chronic proteinuria and hematuriaXerosis cutis, palmoplantar keratoderma, nail dystrophy216 (F)Switzerland-Italyc.[1A>G]None121 (<147)2.3 (<6)333 (<390)ECG: n/dEcho: Normal resultsDiffuse alopecia, nail dystrophy, xerosis cutisSpeech delay319 (F)Switzerland-Italyc.[1A>G]None526 (<147)23.7 (<6)874 (<390)ECG: n/dEcho: Normal resultsMild diffuse alopecia, xerosis cutis, palmoplantar keratoderma, nail dystrophy426 (M)Switzerland-Germanyc.[2T>C]Tachycardia, extrasystoles182 (<168)7.7 (<6)82 (<390)ECG: Normal resultsEcho: Normal resultsDevelopmental and fine motor skill delay5346 (F)Germanyc.[1A>G]None66 (<170)15 (<25)695.7 (<169)ECG: Nonspecific changesEcho: Mild systolic dysfunction with dilatation of left ventricleComplete scalp and body hair loss636 (F)Germanyc.[1A>G]None95 (<149)64.9 (<24)60.1 (<40)ECG: n/dEcho: n/d7436 (F)Germanyc.[1A>G]None74 (<168)19 (<25)170 (<125)ECG: n/dEcho: n/dComplete scalp and body hair loss.8512 (M)Germanyc.[1A>G]None74 (<152)30 (<25, 40.5% of CK)186.7 (<186)ECG: n/dEcho: n/d9639 (M)Italyc.[1A>G]Occasional chest pain at night (2014), improved with medicationn/dn/dn/dECG: Mean = 50 b.p.m. (bradycardia), sporadic ventricular extrasystolesEcho 2014: LV dilatation, EF = 43%.Echo 2018: EF = 43% by Simpson method, global hypokinesia10613 (M)Italyc.[1A>G]None209 (≤200)5.0 (≤5)125.6 (<125)ECG: Normal resultsEcho: Normal results11735 (F)United Statesc.[1A>G]None, but episode with loss of consciousnessn/dn/dn/dECG: Normal resultsEcho: Normal resultsHair thinning in early adulthood, progressive hair lossSeizure disorder of unknown origin12828 (F)Chilec.[1A>G]None Normal6014 (<25)43 (<125)ECG: Normal resultsEcho: Normal resultsModerate alopecia since 11 years of ageFine and dry hair1394 (M)Chilec.[2T>G]None/Normal129 (<308)31 (<25)89 (<125)ECG: n/dEcho: Normal resultsFine and dry hairMild follicular atrophoderma on arms14933 (M)Chilec.[2T>G]Heart murmur (I/IV)75 (<308)11 (<25)926 (<125)ECG: Electric axis diverted to the left. Normal headsets, ventricular complexes and AV conductionIntraventricular conduction altered by anterior left hemiblock.Echo: Severe DCM, diagnosed 2016LV severely dilated in systole (83ml/m2) and diastole (112ml/m2), diffuse hypokinesia and severely depressed systolic function (LVEF = 26%)Mild alopecia, dry hairModerate follicular atrophoderma on cheeks, arms and thighs15925 (M)Chilec.[2T>G]Heart murmur (II/IV), extrasystoles85 (<308)13 (<25)638 (<125)ECG: Isolated ventricular extrasystolesNonspecific alteration of ventricular repolarizationEcho: LV severely dilated, moderate to severe systolic dysfunction (LVEF 30%), mild to moderate functional mitral insufficiency, Carpentier IIIMild alopeciaFine and dry hairMild follicular atrophoderma on thighs16933 (F)Chilec.[2T>G]Heart murmur (I/VI)104 (<308)10 (<25)258 (<125)ECG: NormalEcho: Mild systolic dysfunction of LV, LVEF = 40% normal left atrium and right chambersModerate alopeciaFine and dry hairModerate follicular atrophoderma on thighs and armsHip dysplasia and scoliosis17924 (F)Chilec.[2T>G]None/normal101 (<308)9 (<25)152 (<125)ECG: n/dEcho: Normal with normal/low systolic functionDry hair and moderate alopecia since 13 years of ageMild follicular atrophoderma on arms and thighs1892 (M)Chilec.[2T>G]None141 (<308)40 (<25)210 (<125)ECG: n/dEcho: NormalMild alopecia, dry hair199Death at age 39 (M)Chilec.[2T>G]Cardiac death———DCM from history only—209Death at age 54 (F)Chilec.[2T>G]Cardiac death———DCM from history only—Abbreviations: AV, atrioventricular; BP, blood pressure; CK, creatine kinase; CKMB, CK muscle band; DCM, dilated cardiomyopathy; ECG, electrocardiography; Echo, echocardiography; EF, ejection fraction; F, female; LV, left ventricle; LVEF, left ventricular ejection fraction; M, male; MRI, magnetic resonance imaging; n/d, not done; RV, right ventricle.1 Values in bold exceed reference values. Open table in a new tab Abbreviations: AV, atrioventricular; BP, blood pressure; CK, creatine kinase; CKMB, CK muscle band; DCM, dilated cardiomyopathy; ECG, electrocardiography; Echo, echocardiography; EF, ejection fraction; F, female; LV, left ventricle; LVEF, left ventricular ejection fraction; M, male; MRI, magnetic resonance imaging; n/d, not done; RV, right ventricle. Two examined patients had been diagnosed with DCM before our study (patients 9 and 14). The latter had a positive family history with cardiac death of a brother and mother, both of whom also had skin fragility (patients 19 and 20). Three unrelated patients had neurological involvement: patient 4 with delay of cognitive and motor development, patient 2 with speech delay, and patient 11 with seizures of unknown origin (Table 1). Because missense and pathologic in frame mutations of KLHL24 were recently linked to neurological disease (Anazi et al., 2017Anazi S. Maddirevula S. Salpietro V. Asi Y.T. Alsahli S. Alhashem A. et al.Expanding the genetic heterogeneity of intellectual disability.Hum Genet. 2017; 136: 1419-1429Crossref PubMed Scopus (87) Google Scholar) and because KLHL24 is involved in the regulation of the function of kainate receptors (Laezza et al., 2008Laezza F. Wilding T.J. Sequeira S. Craig A.M. Huettner J.E. The BTB/kelch protein, KRIP6, modulates the interaction of PICK1 with GluR6 kainate receptors.Neuropharmacology. 2008; 55: 1131-1139Crossref PubMed Scopus (18) Google Scholar), these results might also be of significance. This is supported by a recent case report (Yenamandra et al., 2018Yenamandra V.K. van den Akker P.C. Lemmink H.H. Jan S.Z. Diercks G.F.H. Vermeer M. et al.Cardiomyopathy in epidermolysis bullosa simplex patients with mutations in the KLHL24 gene [epub ahead of print].Br J Dermatol. 2018; 179: 1181-1183Crossref PubMed Scopus (19) Google Scholar). Laboratory examinations showed normal values for kidney, liver, pancreas, and thyroid parameters. In 12 of 16 tested patients, NT-pro-BNP, a specific and prognostic biomarker for heart disease (Zile et al., 2016Zile M.R. Claggett B.L. Prescott M.F. McMurray J.J.V. Packer M. Rouleau J.L. et al.Prognostic implications of changes in N-terminal pro-B-type natriuretic peptide in patients with heart failure.J Am Coll Cardiol. 2016; 68: 2425-2436Crossref PubMed Scopus (213) Google Scholar). was increased. All adult patients with more than 2-fold elevated NT-pro-BNP levels (n = 5) had significant dysfunction on echocardiography and/or cardiac magnetic resonance imaging (Figure 1i–l). Creatine kinase muscle band was elevated in 7 of the 16 patients. Fifteen patients were evaluated by cardiology, of whom six were diagnosed with DCM (40%); the youngest was 25 years old (patient 15). None of the newly diagnosed patients (patients 1, 5, 15, and 16) had reported cardiac symptoms (Table 1). Taken together, in this cohort of 20 patients with EBS-KLHL24, 17 (85%) had evidence of cardiac involvement with either elevated cardiac biomarkers or documented DCM (8/20 patients [40%]), leading to death at an early age in two of them. DCM is defined as ventricular dilatation with impaired ventricular systolic function (left ventricular ejection fraction < 50%) in the absence of features of different phenotypes of cardiomyopathy or evidence of acquired heart disease (e.g., coronary artery disease). Early, even presymptomatic intervention improves outcome (Burke et al., 2016Burke M.A. Cook S.A. Seidman J.G. Seidman C.E. Clinical and mechanistic insights into the genetics of cardiomyopathy.J Am Coll Cardiol. 2016; 68: 2871-2886Crossref PubMed Scopus (176) Google Scholar). DCM occurs as a familial disease in 20%–35% of cases with more than 30 genes identified. Onset of familial DCM tends to be earlier in life than average. There is significant variability explained by modifying genetic and acquired risk factors (Burke et al., 2016Burke M.A. Cook S.A. Seidman J.G. Seidman C.E. Clinical and mechanistic insights into the genetics of cardiomyopathy.J Am Coll Cardiol. 2016; 68: 2871-2886Crossref PubMed Scopus (176) Google Scholar). DCM in EB may occur as a primary feature when due to PLEC, JUP, or DSP mutations (Fine et al., 2014Fine J.-D. Bruckner-Tuderman L. Eady R.A.J. Bauer E.A. Bauer J.W. Has C. et al.Inherited epidermolysis bullosa: updated recommendations on diagnosis and classification.J Am Acad Dermatol. 2014; 70: 1103-1126Abstract Full Text Full Text PDF PubMed Scopus (625) Google Scholar) or as a secondary complication in severe dystrophic and junctional EB (Lara-Corrales et al., 2010Lara-Corrales I. Mellerio J.E. Martinez A.E. Green A. Lucky A.W. Azizkhan R.G. et al.Dilated cardiomyopathy in epidermolysis bullosa: a retrospective, multicenter study.Pediatr Dermatol. 2010; 27: 238-243Crossref PubMed Scopus (28) Google Scholar). KLHL24 is expressed at similar levels in keratinocytes and cardiomyocytes (see Supplementary Figure S1 online). As in the skin, cardiac KLHL24 may regulate the degradation of structural cytoskeletal proteins involved in mechanical resilience. KLHL24 was also identified as interacting with components of the COP9 signalosome, a critical regulator of the cullin-RING family of ubiquitin ligases activity (Bennett et al., 2010Bennett E.J. Rush J. Gygi S.P. Harper J.W. Dynamics of cullin-RING ubiquitin ligase network revealed by systematic quantitative proteomics.Cell. 2010; 143: 951-965Abstract Full Text Full Text PDF PubMed Scopus (276) Google Scholar, Sowa et al., 2009Sowa M.E. Bennett E.J. Gygi S.P. Harper J.W. Defining the human deubiquitinating enzyme interaction landscape.Cell. 2009; 138: 389-403Abstract Full Text Full Text PDF PubMed Scopus (1179) Google Scholar). The dysfunction of the COP9 signalosome has been associated with DCM in mice (Su et al., 2011Su H. Li J. Menon S. Liu J. Kumarapeli A.R. Wei N. et al.Perturbation of cullin deneddylation via conditional Csn8 ablation impairs the ubiquitin-proteasome system and causes cardiomyocyte necrosis and dilated cardiomyopathy in mice.Circ Res. 2011; 108: 40-50Crossref PubMed Scopus (81) Google Scholar, Su et al., 2013Su H. Li J. Osinska H. Li F. Robbins J. Liu J. et al.The COP9 signalosome is required for autophagy, proteasome-mediated proteolysis, and cardiomyocyte survival in adult mice.Circ Heart Fail. 2013; 6: 1049-1057Crossref PubMed Scopus (46) Google Scholar). Here, we provide evidence that patients with EBS-KLHL24 display potentially life-threatening DCM in early adulthood. Although dilated cardiomyopathy may be a final common pathway of a variety of acquired and inherited cardiac conditions, none of our patients with DCM showed a different cardiac phenotype (e.g., hypertrophic cardiomyopathy or restrictive cardiomyopathy) or heart disease (e.g., coronary artery disease, cardiac arrhythmias). Our data are supported by two other reports. Recently, severe cardiomyopathy was reported in a single case of EBS-KLHL24 (Yenamandra et al., 2018Yenamandra V.K. van den Akker P.C. Lemmink H.H. Jan S.Z. Diercks G.F.H. Vermeer M. et al.Cardiomyopathy in epidermolysis bullosa simplex patients with mutations in the KLHL24 gene [epub ahead of print].Br J Dermatol. 2018; 179: 1181-1183Crossref PubMed Scopus (19) Google Scholar), and homozygous KLHL24 loss-of-function mutations were found in two siblings with hypertrophic cardiomyopathy with glycogen accumulation in cardiomyocytes (Hedberg-Oldfors et al., 2016Hedberg-Oldfors C. Danielsson O. Hübbert L. Nennesmo I. Abramsson A. Banite R. et al.Hypertrophic cardiomyopathy and abnormal glycogen storage in heart and skeletal muscle associated with inactivation of KLHL24.Neuromuscula Disord. 2016; 26: S152Abstract Full Text Full Text PDF Google Scholar). DCM in EBS-KLHL24 may be missed because skin fragility and blistering improve with age, leading to infrequent follow-up evaluations. Moreover, because of reduced physical activity because of skin fragility and slow development of DCM, patients may not experience early cardiac symptoms. Thus, regular screening for cardiac involvement to identify presymptomatic DCM is required. Given its high sensitivity, serial measurements of NT-pro-BNP levels along with careful history taking may be the optimal screening tool (Zile et al., 2016Zile M.R. Claggett B.L. Prescott M.F. McMurray J.J.V. Packer M. Rouleau J.L. et al.Prognostic implications of changes in N-terminal pro-B-type natriuretic peptide in patients with heart failure.J Am Coll Cardiol. 2016; 68: 2425-2436Crossref PubMed Scopus (213) Google Scholar). In the case of cardiomyopathy, timely implementation of preventive measures, such as heart failure medication or device therapy, may likely improve outcomes. This study was likely crucial for the survival of patient 1, who initially refused echocardiogram for lack of clinical symptoms. His ejection fraction turned out to be 27%. If EBS-KLHL24 is clinically suspected, genetic testing and cardiac monitoring are mandatory. The authors state no conflict of interest. We thank the patients and their families for participation in this study. Gabriele Grüninger is acknowledged for expert technical assistance. Most of this study was supported by Debra International (HAS 1 CH) and the Chilean whole-exome sequencing data analysis by the CONICYT FONDEQUIP EQM150093 and EQM140157. Download .pdf (.11 MB) Help with pdf files Supplementary Material and Supplementary Figure S1 KLHL24: Beyond Skin FragilityJournal of Investigative DermatologyVol. 139Issue 1PreviewKLHL24 mutations have recently been associated with epidermolysis bullosa simplex. Initial studies focused on skin fragility. However, the picture of KLHL24 mutations causing extracutaneous human disease is emerging, with dilated cardiomyopathy as a strong association. In addition, neurological disease is suspected as well. Careful clinical follow-up and functional studies of (mutated) KLHL24 in these tissues are needed. Full-Text PDF Open Archive