Author + information
- Received June 10, 2016
- Revision received August 29, 2016
- Accepted September 9, 2016
- Published online December 13, 2016.
- Ting-Rong Hsu, MDa,b,
- Sheng-Che Hung, MDc,d,e,
- Fu-Pang Chang, MDf,
- Wen-Chung Yu, MDg,
- Shih-Hsien Sung, MDg,
- Chia-Lin Hsu, PhDh,
- Ivan Dzhagalov, PhDh,
- Chia-Feng Yang, MDb,i,
- Tzu-Hung Chu, MDb,
- Han-Jui Lee, MDc,
- Yung-Hsiu Lu, BSb,
- Sheng-Kai Chang, PhDb,
- Hsuan-Chieh Liao, BSj,
- Hsiang-Yu Lin, MD, PhDk,
- Tsan-Chieh Liao, MDl,
- Pi-Chang Lee, MDb,
- Hsing-Yuan Li, MD, PhDb,
- An-Hang Yang, MD, PhDf,
- Hui-Chen Ho, BSm,
- Chuan-Chi Chiang, PhDj,
- Ching-Yuang Lin, MD, PhDn,
- Robert J. Desnick, MD, PhDo,∗∗ ( and )
- Dau-Ming Niu, MD, PhDa,b,p,q,∗ ()
- aInstitute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
- bDepartment of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan
- cDepartment of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
- dSchool of Medicine, National Yang Ming University, Taipei, Taiwan
- eDepartment of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan
- fPathology and Laboratory Medicine Department, Taipei Veterans General Hospital, Taipei, Taiwan
- gDivision of Cardiology, Department of Medicine, Taipei Veterans General Hospital and National Yang-Ming University, School of Medicine, Taipei, Taiwan
- hInstitute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
- iInstitute of Environmental and Occupational Health Sciences, National Yang-Ming University, Taipei, Taiwan
- jNeonatal Screening Center, Chinese Foundation of Health, Taipei, Taiwan
- kDepartment of Pediatrics, Mackay Memorial Hospital and Department of Medicine, Mackay Medical College, Taipei, Taiwan
- lDepartment of Radiology, Zhongxiao Branch, Taipei City Hospital, Taipei, Taiwan
- mTaipei Institute of Pathology, Taipei, Taiwan
- nCollege of Medicine, China Medical University, Taichung, Taiwan
- oDepartment of Genetics & Genomic Sciences, The Icahn School of Medicine at Mount Sinai, New York, New York
- pTaiwan Clinical Trial Consortium in Fabry Disease, Taipei, Taiwan
- qDepartment of Medical Research, Taipei Veterans General Hospital, Taipei, Taiwan
- ↵∗Reprint requests and correspondence:
Dr. Dau-Ming Niu, Department of Pediatrics, Taipei Veterans General Hospital, No. 201, Section 2, Shih-Pai Road, Taipei 112, Taiwan.
- ↵∗∗Dr. Robert J. Desnick, Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Place, New York, New York 10029.
Background Recently, several studies revealed a much higher prevalence of later onset Fabry disease (FD) than previously expected. It suggested that later onset FD might present as an important hidden health issue in certain ethnic or demographic populations in the world. However, the natural history of its phenotype has not been systemically investigated, especially the cardiac involvement.
Objectives The study analyzed a large-scale newborn screening program for FD to understand the natural course of later onset FD.
Methods To date, 916,383 newborns have been screened for FD in Taiwan, including more than 1,200 individuals with the common, later onset IVS4+919G>A (IVS4) mutation. Echocardiography was performed in 620 adults with the IVS4 mutation to analyze the prevalence of left ventricular hypertrophy (LVH), and gadolinium-enhanced cardiac magnetic resonance imaging was performed in 129 patients with FD, including 100 IVS4 adults.
Results LVH was observed in 67% of men and 32% of women older than 40 years. Imaging evidenced significant late gadolinium enhancement in 38.1% of IVS4 men and 16.7% of IVS4 women with the IVS4 mutation but without LVH. Seventeen patients underwent endomyocardial biopsies, which revealed significant globotriaosylceramide substrate accumulation in their cardiomyocytes.
Conclusions Significant cardiomyocyte substrate accumulation in IVS4 patients led to severe and irreversible cardiac fibrosis before development of LVH or other significant cardiac manifestations. Thus, it might be too late to start enzyme replacement therapy after the occurrence of LVH or other significant cardiac manifestations in patients with later onset FD. This study also indicated the importance of newborn screening for early detection of the insidious, ongoing, irreversible cardiac damage in patients with later onset FD.
Fabry disease (FD), an X-linked lysosomal storage disorder (MIM 301500), results from mutations in the α-galactosidase A gene (GLA) that cause deficient α-galactosidase A (α-Gal A) activity and the progressive systematic accumulation of globotriaosylceramide (Gb3) and related glycosphingolipids, particularly in lysosomes of the heart, kidneys, skin, and brain.
The disease has 2 major phenotypes, the classic (type 1) and the later onset (type 2) subtypes (1–5). On the basis of recent newborn screening studies, the incidence of patients with the later onset phenotype is much higher than that of the classic phenotype (6–12). Affected boys with the type 1 classic phenotype have little or no α-Gal A activity and have onset of acroparesthesias, hypohidrosis, angiokeratomas, or a characteristic corneal dystrophy in childhood or adolescence (13). As they age, affected men with the type 1 phenotype develop progressive multisystemic involvement leading to renal failure, hypertrophic cardiomyopathy (HCM), or cerebrovascular disease (1). Men with the type 2 later onset phenotype have residual α-Gal A activity, little or no vascular endothelial Gb3 accumulation, and lack of the early clinical manifestations of patients with the type 1 phenotype (1–3,14). However, type 2 men develop severe cardiac disease or renal failure in the fourth to seventh decades of life (1–3,14). Of interest, and without a current explanation, the type 2 phenotype tends to have mutation-specific cardiac or kidney involvement, although some men develop both with age (15).
Here, we report the findings in patients with the type 2 mutation IVS4+919G>A (IVS4) that primarily presents with progressive cardiac involvement, leading to HCM and eventual heart failure. In Taiwan, we initiated newborn screening for FD, and found the IVS4 mutation was unusually frequent, occurring in about 1 in 1,600 boys (7). As of December 2015, more than 1,200 individuals with the IVS4 mutation had been identified at our center.
The natural course of the type 2 phenotype with primary cardiac disease is largely unknown, but understanding the early signs of cardiac involvement is relevant to determining when to initiate enzyme replacement therapy (ERT) to improve the cardiac outcome. Moreover, there are no well-established treatment guidelines for type 2 cardiac patients. In Taiwan, ERT can be initiated only after presence of HCM or significant cardiac impairment. However, recent studies revealed that for long-term improvement in myocardial morphology and function, ERT should be initiated before myocardial fibrosis has developed (16,17). To further our understanding of the pathogenesis of the type 2 cardiac phenotype and to update treatment guidelines, we used gadolinium-enhanced cardiac magnetic resonance (GE-CMR) imaging to investigate the development of myocardial fibrosis in patients with or without cardiac hypertrophy.
The methodology and results of the newborn screening program for FD in Taiwan have been previously described (7,18). From January 1, 2008, to December 31, 2015, a total of 916,383 newborns were screened.
Since 2008, 620 adults with the IVS4 mutation—identified through screening the families of newborns with the IVS4 mutation—were enrolled in this study. All participants were examined by 2 experienced cardiologists who were blind to those with a GLA mutation. Echocardiography was performed in accord with the recommendations of the American Society of Echocardiography using ACUSON equipment (Antares, Siemens AG, Munich, Germany; Sono 7500, Hewlett-Packard Company, Palo Alto, California). Left ventricular mass (LVM) was calculated according to the Devereux cube formula (19). LVM was normalized to height (m) to 2.7 power (left ventricular mass index [LVMI] = LVM/height2.7) (20). Left ventricular hypertrophy (LVH) was defined as LVMI >51 g/m2.7 in men and LVMI >48 g/m2.7 in women (21).
Since 2010, a total of 129 patients with FD have been enrolled in GE-CMR studies (57.4% men; 54.0 ± 12.3 years of age, range 19 to 83 years of age). There were 100 IVS4 patients (64 men), 22 type 1 patients (5 men), and 7 type 2 patients with primarily renal involvement (5 men). All of the IVS4 participants were 35 years of age or older, whereas the non-IVS4 participants were 18 years or older.
All study subjects underwent GE-CMR using a 3.0-T scanner (Discovery MR750, GE Healthcare, Milwaukee, Wisconsin). In addition to routine cine magnetic resonance imaging, a breath-hold electrocardiogram (ECG)-gated 2-dimensional myocardial delayed enhancement sequence (8 mm slice thickness; both short-axis and 4-chamber views; field of view, 340 × 316 mm; matrix, 256 × 192) was applied to detect myocardial late gadolinium enhancement 10 min after intravenous administration of 0.1 mmol kg–1 gadobutrol (17). LVH assessed by GE-CMR was defined by an LVMI of >39 g/m2.7 in women or >48 g/m2.7 in men (22). Important cardiac parameters, such as posterior and interventricular wall thickness and ejection fraction, were calculated (23).
Endomyocardial biopsy and histologic studies
As required by the Taiwan treatment guidelines for FD, all IVS4 patients applying for ERT funding from the National Health Insurance must undergo endomyocardial biopsy to demonstrate that FD was the primary cause of their cardiomyopathy. Seventeen IVS4 patients who had myocardial fibrosis without LVH underwent endomyocardial biopsy. According to previous autopsy studies of cardiac Fabry patients, the Fabry pathologic changes in the right ventricle were usually milder than those in the left ventricle (24). However, right heart catheterization and right interventricular septum biopsy was chosen for this study because right ventricle biopsy is safer and easier than left ventricle biopsy. In addition, coronary angiography was performed in patients with the IVS4 mutation if they had a risk of coronary artery disease (CAD) and provided informed consent. CAD was defined as coronary stenosis and >50% narrowing in luminal diameter. Regarding cardiac biopsy, catheterization was approached via the right internal jugular vein under digital x-ray guidance. A flexible endomyocardial bioptome was inserted into the right ventricle and 2 to 3 specimens were obtained from interventricular septum and submitted for histological examination.
Cardiac specimens were fixed in 10% buffered formalin and embedded in paraffin. The sections were stained with hematoxylin and eosin and Masson’s trichrome, then subjected to light microscopic analysis. For electron microscopy, tissues were fixed in 2.5% glutaraldehyde in phosphate buffer, post-fixed with 1% osmium tetroxide in Sorenson’s phosphate buffer, followed by dehydration through a graded series of ethanol washes, and embedded in Spurr’s Epon. Semithin sections were cut from the block and stained with toluidine blue for microscopic review. Ultrathin sections were then prepared and examined by electron microscopy.
Descriptive statistics (mean ± SD) were used to describe the basic features of the data in this study. Due to the small number of patients and the uncontrolled nature of this study, no inferential statistics were used. Results were presented as actual measurements from individual patients. SPSS version 20 (IBM Corporation, Armonk, New York) was used for descriptive statistics.
Of the 916,383 newborns screened over 7 years, 476,909 (52%) were boys and 439,474 (48%) were girls. A total of 441 newborns (324 boys) had low plasma α-Gal A activity and a GLA mutation (Table 1), including 381 with an IVS4 mutation, 7 with type 1 classic mutations, 16 with type 2 later onset mutations, and 37 with novel mutations. Subsequent family studies identified >1,400 individuals with these mutations, of whom 83.5% (>1,200) had the type 2 mutation, IVS4+919G>A.
We investigated the age at which LVH was detected in men and women with the IVS4 mutation. Only 2 men (4%) and 3 women (2%) <40 years of age had borderline LVH. However, the onset of LVH increased rapidly in the IVS4 adults who were >40 years of age for both men and women. Actually, about 67% of male and 32% of female adults older than 40 years of age had developed LVH (Figure 1).
Imaging and biopsy
Of 100 IVS4 participants, 28 (22 men) had LVH on GE-CMR, whereas 72 IVS4 (42 men) did not. GE-CMR in adults with LVH revealed that 17 of 22 (77.3%) men and no women had late gadolinium enhancement (LGE), whereas 16 of 42 (38.1%) men and 5 of 30 (16.7%) women without LVH had LGE. Of note, 2 IVS4 men <40 years of age had significant LGE on GE-CMR, but without LVH.
Of 5 men with the type 1 classic phenotype, 2 had LVH without LGE and 1 man had LGE without LVH. For type 1 female heterozygotes, 9 of 17 (52.9%) had LVH and 3 (33.3%) had LGE. The other 8 female patients had neither LVH nor LGE. In the type 2 renal phenotype, 1 man and 1 woman had both LVH and LGE.
We identified a total of 22 adult patients with FD who had LGE but no LVH. Of these 22 patients, 12 (9 men) underwent coronary angiography (Table 2). Among these 12 patients, 2 (Patients #9 and #19) had both coronary stenosis and LGE distribution in the corresponding territory. Two patients (#17 and #20) had positive angiographic findings but LGE did not distribute in the corresponding vascular territory. The remaining 8 patients had negative coronary angiography. Of the other 10 patients who did not undergo coronary angiography, only 1 58-year-old man (#10) had an LGE pattern characteristic of CAD. However, all the patients with an LGE pattern of coronary distribution underwent cardiac biopsy, which revealed significant Gb3 accumulation in their cardiomyocytes. This finding indicated that most of the LGE in these patients was not caused by CAD.
Seventeen IVS4 individuals who had myocardial fibrosis without LVH underwent endomyocardial biopsies and all had significant pathological changes and Gb3 accumulation in their cardiomyocytes. The relationship between LVMI and LGE in male and female type 2 IVS4 patients is shown in Figure 2. Three cases with representative LGE on GE-CMR and histopathologic changes are shown in Figure 3. The demographic data, LV function, ECG, and clinical manifestations of the patients with cardiac fibrosis without LVH are presented in Table 2.
Our newborn screening program found that the incidence of the type 2 later onset GLA mutation, IVS4+919G>A, was unusually high in the Taiwan Chinese population. The IVS4 mutation also was identified in Kagoshima, Japan (25), and in patients with HCM in Mainland China, Singapore, Malaysia, and Vietnam (26). On the basis of Chinese migrations, the IVS4 mutation may be prevalent in southeast China and Southeast Asia. Newborn screening in Europe and the United States revealed an incidence of the type 2 phenotype that was greater than those of the respective population’s type 1 classic phenotype (6–12). These findings indicate that the type 2 phenotype may be an important hidden health issue in certain ethnic or demographic populations in the world.
However, the natural course of the type 2 later onset phenotype remains largely unknown, particularly due to its misdiagnosis as common varieties of heart or renal disease. In Taiwan, we have identified >1,200 individuals with the IVS4 mutation, providing the opportunity to investigate the natural course of these later onset patients who have a single causative mutation by cross-section analysis within a single center (Central Illustration). Few IVS4 patients under 40 years of age had cardiac hypertrophy or fibrosis. However, LVH was present and increased rapidly with age in the IVS4 adults ≥40 years of age and the frequency increased decade by decade (Figure 1). Because therapeutic efforts should be initiated before irreversible hypertrophy and/or fibrosis, we suggest initiating close follow-up of the cardiac conditions of these IVS4 individuals much earlier than 40 years of age.
The underlying mechanisms responsible for progressive LVH in FD have not been fully elucidated; however, the secondary effects of the lysosomal glycosphingolipid deposits should play important roles. Likely secondary effects include inflammatory reactions (27–29), circulating hypertrophy-promoting factors (30,31), or other genetic or environmental factors (32). Tissue fibrosis is always considered the end result of tissue injury, inflammation, and apoptosis; it is also regarded as an irreversible event with little therapeutic intervention available (16,17,33). Cardiac fibrosis stands as a negative cardiac prognostic factor for ERT. A previous study of cardiac-biopsy pathology type 2 patients from our group demonstrated that even though the Gb3 accumulation was dramatically decreased in the cardiomyocytes after long-term ERT, heart function in these patients did not show significant improvement, primarily due to the cardiac fibrosis that was present before initiation of ERT (34). Therefore, it was strongly recommended that ERT should best be administrated before myocardial fibrosis development to maintain long-term myocardial morphology and function (16).
Here, we reported that 38.1% of male and 16.7% of female FD patients, even without LVH, had already developed cardiac fibrosis. These findings suggest that severe and irreversible cardiac damage can occur before the development of cardiac hypertrophy in type 2 patients. Recently, Niemann et al. (35) published a large CMR imaging study of 104 FD patients (58 women and 46 men). Interestingly, 10 (17.2%) female patients without LVH already had LGE, although LGE was not found in male patients without LVH. On the basis of these results, the authors concluded that cardiomyopathy progression in FD differs in men and women, and that only the women develop fibrosis before hypertrophy. However, our study showed that a large portion of type 2 later onset men also developed cardiac fibrosis before LVH. Moreover, we also identified 1 type 1 classic man who had LGE before LVH. Together, our findings suggested that the development of fibrosis might occur before LVH in both affected men and heterozygotes with FD.
It is noteworthy that most (88.2% men, 60% women) of our non-LVH patients did not have significant FD cardiac manifestations, even when they already had significant fibrosis and extensive Gb3 accumulation in their cardiomyocytes. Many of them had varying conductive abnormalities or dyspnea on exertion (Table 2), but most did not have sufficient symptoms to seek medical attention. Thus, cardiac disease in Fabry patients can progress silently, before significant clinical symptoms occur. These findings highlighted the importance of early diagnosis and therapeutic intervention in all FD patients. Moreover, the late initiation of ERT limited the effectiveness of the treatment as the fibrosis may progress early in the course of the disease.
Our findings also highlighted the importance of newborn screening: it provides early detection of the future insidious and irreversible cardiac damage that occurs in adult type 2 later onset patients. In contrast, type 1 classic men are typically diagnosed earlier, often in childhood or adolescence due to the characteristic early manifestations. These patients often receive ERT before the occurrence of irreversible cardiac damage. However, without newborn screening, early detection of type 2 patients (e.g., IVS4) would be difficult, as they usually present late with advanced cardiac or renal manifestations.
Our findings further emphasized the importance of early intervention for type 2 patients with cardiac disease. Currently, many patients already have HCM and its related manifestations. Clearly, biomarkers of early cardiac disease are needed to guide initiation of ERT in type 2 patients with cardiac disease. Our results also suggested that current echocardiography, routine ECG, or even GE-CMR is not sensitive enough to detect the early cardiac damage in type 2 patients. Recent studies have shown that T1-mapping CMR imaging and strain echocardiography might be more sensitive to detect early cardiac manifestations (36,37). Therefore, in Taiwan, we suggest that adult patients with the IVS4 mutation should be carefully monitored by performing strain echocardiography annually and T1-mapping CMR every 2 to 3 years, particularly in men >30 years of age and women >40 years of age. If these methods provide any abnormal results, cardiac biopsy should be performed. After the detection of significant GB3 accumulation in cardiac biopsy, ERT should be initiated before the occurrence of significant cardiac manifestations. Although earlier therapy is warranted for improved outcomes in patients with FD, no data indicating that early treatment can prevent fibrosis have been provided. Therefore, this concept should be further investigated, especially in our IVS4 patient group.
During the family study of the IVS4 newborns, not all grandparents were willing to come to our hospital for confirmatory diagnosis. It is possible that the grandparents who had some manifestations of heart disease were more willing to come for confirmatory diagnoses than those who did not. Therefore, there might have been a bias in regard to overestimation of LVH prevalence of IVS4 adults in this study.
The cardiac damage experienced by FD patients can progress in silence even when severe and irreversible cardiac damage has occurred. This may mean that when significant clinical symptoms and signs of cardiac involvement have occurred, it may already be too late to treat FD patients.
COMPETENCY IN PATIENT CARE AND PROCEDURAL SKILLS: Cardiac damage in patients with FD can progress without overt clinical manifestations even after irreversible cardiac damage has appeared.
TRANSLATIONAL OUTLOOK: Additional investigation is needed to define criteria that facilitate earlier detection of cardiac involvement in patients with FD and determine the optimal timing of ERT.
This work was partly supported by the National Science Council, Taiwan (No. NSC-100-2325-B-010-014) and Taipei Veterans General Hospital (No. V101C-129 and V101C-187). Dr. Desnick has served as a consultant for Genzyme/Sanofi, Amicus Therapeutics, and Sangamo BioSciences; owns founder shares of Amicus Therapeutics; owns stock options in Sangamo BioSciences; and receives royalties from Genzyme/Sanofi and Shire HGT. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Drs. T.-R. Hsu and Hung contributed equally to this work. Michelle Kitteson, MD, PhD, served as Guest Editor for this article.
- Abbreviations and Acronyms
- coronary artery disease
- enzyme replacement therapy
- Fabry disease
- Gal A
- galactosidase A
- gadolinium-enhanced cardiac magnetic resonance
- α-galactosidase A gene
- hypertrophic cardiomyopathy
- late gadolinium enhancement
- left ventricular hypertrophy
- left ventricular mass
- left ventricular mass index
- Received June 10, 2016.
- Revision received August 29, 2016.
- Accepted September 9, 2016.
- American College of Cardiology Foundation
- Desnick R.J.,
- Ioannou Y.A.,
- Eng C.M.
- Lin H.Y.,
- Chong K.W.,
- Hsu J.H.,
- et al.
- Weidemann F.,
- Niemann M.,
- Breunig F.,
- et al.
- Lang R.M.,
- Bierig M.,
- Devereux R.B.,
- et al.
- de Simone G.,
- Daniels S.R.,
- Devereux R.B.,
- et al.
- Rickers C.,
- Wilke N.M.,
- Jerosch-Herold M.,
- et al.
- Niu D.M.,
- Yu W.C.,
- Hsu T.R.,
- Chang F.P.,
- Sung S.H.,
- Chu T.H.
- Chen K.H.,
- Chien Y.,
- Wang K.L.,
- et al.
- Barbey F.,
- Brakch N.,
- Linhart A.,
- et al.
- Brakch N.,
- Dormond O.,
- Bekri S.,
- et al.
- Desnick R.J.,
- Doheny D.
- Niemann M.,
- Herrmann S.,
- Hu K.,
- et al.
- Sado D.M.,
- White S.K.,
- Piechnik S.K.,
- et al.
- Thompson R.B.,
- Chow K.,
- Khan A.,
- et al.