Hao-Chuan Liu

A large-scale nationwide newborn screening program for pompe disease in Taiwan: Towards effective diagnosis and treatment

The aim of this study was to: (a) analyze the results of a large‐scale newborn screening program for Pompe disease, and (b) establish an effective diagnostic protocol to obtain immediate, valid diagnosis of infantile‐onset Pompe disease (IOPD) to promote earlier treatment and better outcomes. In this study, 402,281 newborns were screened for Pompe disease from January 1, 2008 to May 1, 2012. Infants with low acid α‐glucosidase (GAA) activity were referred to Taipei Veterans General Hospital for diagnostic confirmation. Physical examination, biochemical parameter (creatine kinase [CK], alanine transaminase, aspartate aminotransferase, and lactate dehydrogenase), and echocardiogram assessments were performed immediately to effectively differentiate IOPD from suspected late‐onset Pompe disease (LOPD) or false‐positive cases with pseudodeficiency mutation. Six infants with IOPD all presented with hypotonia, extremely low GAA enzyme activity (≤0.5 µmol/L/hr) in initial dried blood spot analysis, high CK (≥250 U/L), and high left ventricular mass index (LVMI, ≥80 g/m2). By analyzing these parameters, IOPD was distinguished effectively and immediately from suspected LOPD and false‐positive cases. Except for the first referred case, five of the infants with IOPD received first‐time enzyme replacement therapy (ERT) within 4 hr of admission and exhibited marked improvement. Our findings indicate that certain clinical manifestations (hypotonia, high CK, enlarged LVMI, and extremely low GAA enzyme activity in initial dried blood spot analysis) can help in the rapid and effective differentiation of patients with IOPD from other patient with low GAA activity. Such differentiation allows for the early application of first‐time ERT and leads to better outcomes.

Effects of enzyme replacement therapy for cardiac-type Fabry patients with a Chinese hotspot late-onset Fabry mutation (IVS4+919G>A)

Objective Current studies of newborn screening for Fabry disease in Taiwan have revealed a remarkably high prevalence of cardiac-type Fabry disease with a Chinese hotspot late-onset Fabry mutation (IVS4+919G>A). Design Retrospective cohort study. Setting Tertiary medical centre. Participants 21 patients with cardiac-type Fabry disease (15 men and 6 women) as well as 15 patients with classic Fabry disease (4 men and 11 women) treated with biweekly intravenous infusions of agalsidase β (1 mg/kg) or agalsidase α (0.2 mg/kg) for at least 6 months. Outcome measures These data were collected at the time before enzyme replacement therapy (ERT) began and followed up after ERT for at least 6 months, including patient demographics, medical history, parameter changes of cardiac status and renal functions, plasma globotriaosylsphingosine (lyso-Gb3) and Mainz Severity Score Index. Results After 6–39 months of ERT, plasma lyso-Gb3 was found to be reduced in 89% (17/19) and 93% (14/15) of patients with cardiac-type and classic Fabry disease, respectively, which indicated an improvement of disease severity. For patients with cardiac-type Fabry disease, echocardiography revealed the reduction or stabilisation of left ventricular mass index (LVMI), the thicknesses of intraventricular septum (IVS) and left posterior wall (LPW) in 83% (15/18), 83% (15/18) and 67% (12/18) of patients, respectively, as well as 77% (10/13), 73% (11/15) and 60% (9/15) for those with classic type. Most patients showed stable renal function after ERT. There were statistically significant improvements (p<0.05) between the data at baseline and those after ERT for values of plasma lyso-Gb3, LVMI, IVS, LPW and Mainz Severity Score Index. No severe clinical events were reported during the treatment. Conclusions ERT is beneficial and appears to be safe for Taiwanese patients with cardiac-type Fabry disease, as well as for those with the classic type.

High-throughput detection of common sequence variations of Fabry disease in Taiwan using DNA mass spectrometry

BACKGROUND In view of the therapeutic benefits resulting from early intervention for Fabry disease, our team has implemented an enzyme-based newborn screening in Taiwan since 2008. However, we found that most heterozygous females cannot be detected. To improve the screening efficiency, a more effective method for GLA gene genotyping is necessary. METHODS As the suspected mutations are limited to only 29 different spots in Taiwanese, a panel of Sequenom iPLEX assay was designed for rapid screening of GLA variations. To determine the accuracy and sensitivity of this assay, previously diagnosed and undiagnosed DNA samples were analyzed by this genotyping assay and Sanger sequencing. In addition, DNA extracted from dried blood spots was also tested. RESULTS Sequenom iPLEX assay is accurate and cost-effective, identifying the sequence variations, which were designated in the panel. It identified common GLA variants in DNA samples extracted from whole blood or dried blood spots with 100% accuracy and sensitivity. CONCLUSIONS Sequenom iPLEX assay is suitable for Fabry newborn screening when hotspot mutations and common variations are known in a well-studied population. In addition, this assay can also be applied for first-line determination of GLA variant sequences in suspected subjects of high-risk patients, or newborns.

Clinical observations on enzyme replacement therapy in patients with Fabry disease and the switch from agalsidase beta to agalsidase alfa

Background: Fabry disease is an X‐linked inherited lysosomal storage disease that can be treated with the enzymes of agalsidase beta (Fabrazyme) and agalsidase alfa (Replagal). Since June 2009, viral contamination of Genzymes production facility has resulted in a worldwide shortage of agalsidase beta, leading to the switch to agalsidase alfa for patients with Fabry disease in Taiwan. Methods: The medical records were retrospectively reviewed for nine male patients with Fabry disease from the start of agalsidase beta treatment until the switch to agalsidase alfa for at least 1 year. Results: After 12–112 months of enzyme replacement therapy (ERT), decreased plasma globotriaosylsphingosine (lyso‐Gb3) was found in five out of seven patients, indicating improvement in disease severity. Among the six patients with available echocardiographic data at baseline and after ERT, all six experienced reductions of left ventricular mass index. Renal function, including microalbuminuria and estimated glomerular filtration rate, showed stability after ERT. Mainz Severity Score Index scores revealed that all nine patients remained stable at 12 months after switching to agalsidase alfa. ERT improved or stabilized cardiac status and stabilized renal function, while reducing plasma lyso‐Gb3. ERT was well tolerated, even among the three patients who had hypersensitivity reactions. Conclusion: The switch of ERT from agalsidase beta to agalsidase alfa appears to be safe after 1 year of follow‐up for Taiwanese patients with Fabry disease.

Functional and biological studies of α-galactosidase A variants with uncertain significance from newborn screening in Taiwan

Fabry disease is an X-linked disorder resulted from deficiency of α-galactosidase A (GLA) activity. In Taiwan, a total of 792,247 newborns were screened from 2008 to 2014 in two newborn screening centers, and 13 variants of uncertain significance (VOUS) in the GLA gene were identified. To determine whether these variants were pathogenic or not, functional, biochemical, clinical and pedigree analyses were performed. In vitro functional assay was established through site-directed mutagenesis, and four in silico tools were used to predict pathogenesis. The enzyme activity of dried blood spots and plasma metabolite lyso-Gb3 level from subjects with the variants were measured. Additionally, clinical manifestations were evaluated extensively from the subjects and their relatives. Our results revealed that p.G104V, p.I232T, p.D322H, and p.G360C all exhibited relatively low residual enzyme activities and elevated plasma lyso-Gb3 level. These data strongly suggest that these Fabry mutations may cause classical or later-onset phenotypes. In contrast, neither significantly clinical symptoms nor elevated lyso-Gb3 level was found in cases with p.P60S, p.A108T, p.S304T, p.R356Q, and p.P362T variants, which may be non-pathogenic or milder forms of Fabry variants. More data need to be included for the patients with p.N53D, p.P210S, p.M296L, and p.K391T variants. The established system provides us more information to classify these GLA variants.

Hepatomegaly and hyperammonemia in a girl with Silver-Russell syndrome caused by maternal uniparental isodisomy of chromosome 7.

© 2014 Wiley Periodicals, Inc.