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/m(2)). 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.

Experiences during newborn screening for glutaric aciduria type 1: Diagnosis, treatment, genotype, phenotype, and outcomes.

BACKGROUND: Glutaric aciduria type 1 (GA-1) is an organic acidemia with potentially severe neurological sequelae. In Taiwan, newborn screening (NBS) for GA-1 began in 2001, but large-scale reporting is lacking. This study describes Taiwan's largest newborn screening population to date. METHODS: Between 2001 and 2015, 1,490,636 newborns were screened for GA-1. Confirmatory examinations included the carnitine loading test. Confirmed patients were treated with a low lysine diet, carnitine, and high-energy intake during illness. Clinical, laboratory, and neuroimaging data were analyzed. RESULTS: Fourteen newborns were diagnosed with GA-1 (incidence: 1/106,474). C5DC concentration was clearly increased after carnitine loading in the affected newborns, but not in false-positive newborns (p = 0.004), indicating that this test is useful as an adjuvant diagnostic method. Eleven patients followed in our hospital were enrolled, namely nine NBS patients and two patients diagnosed clinically. IVS10-2A>C was the most common mutation. Two novel mutations (T36fs and N291K) were identified. Pendular nystagmus was found in two pediatric GA-1 patients. The corresponding pathology was optic atrophy in one patient, but remained undetermined in the other patient. The frequency of encephalopathic crisis decreased substantially following NBS. Among patients diagnosed by NBS, cognitive functioning was better among patients with good compliance than patients with poor compliance (p = 0.03). Abnormalities were detected by brain MRI including diffusion-weighted imaging and apparent diffusion coefficient maps; these affected various brain regions at different stages of the disease. Basal ganglion injuries occurred after an encephalopathic crisis. White matter disease was prevalent among older patients, either with or without an encephalopathic crisis. CONCLUSION: Early diagnosis by newborn screening followed by full compliance with treatment guidelines is important to a good outcome.

The use of high resolution melting analysis to detect Fabry mutations in heterozygous females via dry bloodspots.

BACKGROUND: As an X-linked genetic disorder, Fabry disease was first thought to affect males only, and females were generally considered to be asymptomatic carriers. However, recent research suggests that female carriers of Fabry disease may still develop vital organ damage causing severe morbidity and mortality. In the previous newborn screening, from 299,007 newborns, we identified a total of 20 different Fabry mutations and 121 newborns with Fabry mutations. However, we found that most female carriers are not detected by enzyme assays. METHODS: A streamlined method for high resolution melting (HRM) analysis was designed to screen for GLA gene mutations using a same PCR and melting program. Primer sets were designed to cover the 7 exons and the Chinese common intronic mutation, IVS4+919G>A of GLA gene. RESULTS: The HRM analysis was successful in identifying heterozygous and hemizygous patients with the 20 surveyed mutations. We were also successful in using this method to test dry blood spots of newborns afflicted with Fabry mutations without having to determine DNA concentration before PCR amplification. CONCLUSION: The results of this study show that HRM could be a reliable and sensitive method for use in the rapid screening of females for GLA mutations.