Implementation of newborn screening for mucopolysaccharidosis type IVA and long-term monitoring in Taiwan.

PURPOSE: Mucopolysaccharidosis IVA (MPS IVA) is a rare lysosomal storage disorder arising from a deficiency in N-acetylgalactosamine-6-sulfatase. METHODS: From September 2019 to October 2023, a total of 264,843 Taiwanese newborns underwent screening for MPS IVA using dried blood spots and tandem mass spectrometry. RESULTS: Among the 95 referred infants, 9 (9%) were confirmed to have MPS IVA (group 1), 18 (19%) were highly suspected to have MPS IVA (group 2), 61 (64%) were identified as heterozygotes of MPS IVA (group 3), and 7 (7%) were determined not to have MPS IVA (group 4). A total of 34 different GALNS (HGNC:4122) gene variants were identified through our MPS IVA newborn screening program. The most prevalent variant was c.857C>T p.(Thr286Met), found in 33 cases (29%), followed by c.953T>G p.(Met318Arg) in 22 cases (19%). Intravenous enzyme replacement therapy was initiated in 5 patients at ages ranging from 0.3 to 1.7 years. The estimated incidence of MPS IVA in this screening program was 3.4 per 100,000 live births. CONCLUSION: Because of the progressive nature of MPS IVA, an early diagnosis facilitated by newborn screening and prompt initiation of enzyme replacement therapy before irreversible organ damage occurs may result in improved clinical outcomes.

Genetic and Phenotypic Spectrum of KMT2D Variants in Taiwanese Case Series of Kabuki Syndrome.

Kabuki syndrome (KS) is a rare genetic disorder characterized by distinct facial features, intellectual disability, and multiple congenital anomalies. We conducted a comprehensive analysis of the genetic and phenotypic spectrum of KS in a Taiwanese patient group of 23 patients. KMT2D variants were found in 22 individuals, with missense (26.1%), nonsense (21.7%), and frameshift (17.4%) variants being the most prevalent. One patient had a KMT2D variant of uncertain significance. The most common clinical characteristics included distinct facial features (100%), intellectual disability (100%), developmental delay (95.7%), speech delay (78.3%), hypotonia (69.6%), congenital heart abnormalities (69.6%), and recurrent infections (65.2%). Other abnormalities included hearing loss (39.1%), seizures (26.1%), cleft palate (26.1%), and renal anomalies (21.7%). This study broadens the mutational and phenotypic spectrum of KS in the Taiwanese population, highlighting the importance of comprehensive genetic testing and multidisciplinary clinical evaluations for diagnosis and treatment.

Application of whole exome sequencing in the diagnosis of muscular disorders: a study of Taiwanese pediatric patients.

Background: Muscular dystrophies and congenital myopathies encompass various inherited muscular disorders that present diagnostic challenges due to clinical complexity and genetic heterogeneity. Methods: This study aimed to investigate the use of whole exome sequencing (WES) in diagnosing muscular disorders in pediatric patients in Taiwan. Out of 161 pediatric patients suspected to have genetic/inherited myopathies, 115 received a molecular diagnosis through conventional tests, single gene testing, and gene panels. The remaining 46 patients were divided into three groups: Group 1 (multiplex ligation-dependent probe amplification-negative Duchenne muscular dystrophy) with three patients (6.5%), Group 2 (various forms of muscular dystrophies) with 21 patients (45.7%), and Group 3 (congenital myopathies) with 22 patients (47.8%). Results: WES analysis of these groups found pathogenic variants in 100.0% (3/3), 57.1% (12/21), and 68.2% (15/22) of patients in Groups 1 to 3, respectively. WES had a diagnostic yield of 65.2% (30 patients out of 46), detecting 30 pathogenic or potentially pathogenic variants across 28 genes. Conclusion: WES enables the diagnosis of rare diseases with symptoms and characteristics similar to congenital myopathies and muscular dystrophies, such as muscle weakness. Consequently, this approach facilitates targeted therapy implementation and appropriate genetic counseling.

Illuminating the Genetic Basis of Congenital Heart Disease in Patients with Kabuki Syndrome.

Congenital heart defects (CHDs) affect a substantial proportion of patients with Kabuki syndrome. However, the prevalence and type of CHD and the genotype-phenotype correlations in Asian populations are not fully elucidated. This study performed a retrospective analysis of 23 Taiwanese patients with molecularly confirmed Kabuki syndrome. Twenty-two patients presented with pathogenic variants in the KMT2D gene. Comprehensive clinical assessments were performed. A literature review was conducted to summarize the spectrum of CHDs in patients with Kabuki syndrome. In total, 16 (73.9%) of 22 patients with pathogenic KMT2D variants had CHDs. The most common types of CHD were atrial septal defects (37.5%), ventricular septal defects (18.8%), coarctation of the aorta (18.8%), bicuspid aortic valve (12.5%), persistent left superior vena cava (12.5%), mitral valve prolapse (12.5%), mitral regurgitation (12.5%), and patent ductus arteriosus (12.5%). Other cardiac abnormalities were less common. Further, there were no clear genotype-phenotype correlations found. A literature review revealed similar patterns of CHDs, with a predominance of left-sided obstructive lesions and septal defects. In conclusion, the most common types of CHDs in Taiwanese patients with Kabuki syndrome who presented with KMT2D mutations are left-sided obstructive lesions and septal defects.

22q11.2 Deletion Syndrome in Taiwan: Clinical Presentation and Immune System Status of Patients.

Background: 22q11.2 deletion syndrome (22q11.2DS) is a microdeletion syndrome exhibiting significant clinical phenotype variability. This study aimed to investigate the clinical features, immune profiles, and cognitive abilities of 22q11.2DS patients receiving treatment at MacKay Memorial Hospital in Taipei, Taiwan. Methods: This is a cross-sectional analysis between January 2001 and December 2022. We recruited 27 patients with 22q11.2DS using fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) and array comparative genomic hybridization (aCGH). Our evaluation included patient history, physical examination, laboratory analysis, and cardiac and cognitive assessment. Results: We included 27 patients with 22q11.2DS, 7 (25.9%) of whom were female. The median age of the patients was 17.9 yr. Ninety-three percent of the patients exhibited the characteristic facial features associated with the syndrome. A family history of 22q11.2DS was found in 11.1% of the patients. Furthermore, 74.1% of the patients had a congenital heart defect, the most common of which was tetralogy of Fallot (40.7%). Hypocalcemia was observed in 40.7% of the patients. A low T-cell count was observed in 66.7% of the patients, whereas 18.5% had low immunoglobulin levels. Cognitive assessments revealed that four out of six evaluated patients (66.7%) had an intellectual disability, as evidenced by intellectual quotient scores less than 70. The remaining two patients (33.3%) had a borderline intellectual function. Conclusion: Tetralogy of Fallot, hypocalcemia, immunologic defects, and cognitive impairment were common among our patients. To address the potential multisystem involvement, we recommend that all affected individuals undergo a comprehensive evaluation by a multidisciplinary care team.

Updated Confirmatory Diagnosis for Mucopolysaccharidoses in Taiwanese Infants and the Application of Gene Variants.

Mucopolysaccharidosis (MPS) is a lysosomal storage disease caused by genetic defects that result in deficiency of one specific enzyme activity, consequently impairing the stepwise degradation of glycosaminoglycans (GAGs). Except for MPS II, the other types of MPS have autosomal recessive inheritance in which two copies of an abnormal allele must be present in order for the disease to develop. In this study, we present the status of variant alleles and biochemistry results found in infants suspected of having MPS I, II, IVA, and VI. A total of 324 suspected infants, including 12 for MPS I, 223 for MPS II, 72 for MPS IVA, and 17 for MPS VI, who were referred for MPS confirmation from newborn screening centers in Taiwan, were enrolled. In all of these infants, one specific enzyme activity in dried blood spot filter paper was lower than the cut-off value in the first blood sample, as well asin a second follow-up sample. The confirmatory methods used in this study included Sanger sequencing, next-generation sequencing, leukocyte enzyme fluorometric assay, and GAG-derived disaccharides in urine using tandem mass spectrometry assays. The results showed that five, nine, and six infants had MPS I, II, and IVA, respectively, and all of them were asymptomatic. Thus, a laboratory diagnosis is extremely important to confirm the diagnosis of MPS. The other infants with identified nucleotide variations and reductions in leukocyte enzyme activities were categorized as being highly suspected cases requiring long-term and intensive follow-up examinations. In summary, the final confirmation of MPS depends on the most powerful biomarkers found in urine, i.e., the quantification of GAG-derived disaccharides including dermatan sulfate, heparan sulfate, and keratan sulfate, and analysis of genetic variants can help predict outcomes and guide treatment.

Efficacy of Intravenous Elosulfase Alfa for Mucopolysaccharidosis Type IVA: A Systematic Review and Meta-Analysis.

Mucopolysaccharidosis type IVA (MPS IVA or Morquio A), a lysosomal storage disease with an autosomal recessive inherited pattern, is induced by GALNS gene mutations causing deficiency in N-acetylgalactosamine-6-sulfatase activity (GALNS; EC 3.1.6.4). Currently, intravenous (IV) enzyme replacement therapy (ERT) with elosulfase alfa is employed for treating MPS IVA patients. A systematic literature review was conducted to evaluate the efficacy and safety of IV elosulfase alfa for MPS IVA by searching the National Center for Biotechnology Information, U.S. National Library of Medicine National Institutes of Health (PubMed), Excerpta Medica dataBASE, and Cochrane Library databases, limited to clinical trials. Four cohort studies and two randomized controlled trials, with a total of 550 participants (327 on ERT treatment versus 223 on placebo treatment), satisfied the inclusion criteria. Pooled analysis of proportions and confidence intervals were also utilized to systematically review clinical cohort studies and trials. Per the pooled proportions analysis, the difference in means of urinary keratan sulfate (uKS), 6-min walk test, 3-min stair climb test, self-care MPS-Health Assessment Questionnaire, caregiver assistance and mobility, forced vital capacity, the first second of forced expiration, and maximal voluntary ventilation between the ERT and placebo treatment groups were -0.260, -0.102, -0.182, -0.360, -0.408, -0.587, -0.293, -0.311, and -0.213, respectively. Based on the currently available data, our meta-analysis showed that there is uKS, physical performance, quality of life, and respiratory function improvements with ERT in MPS IVA patients. It is optimal to start ERT after diagnosis.

Newborn Screening Program for Mucopolysaccharidosis Type II and Long-Term Follow-Up of the Screen-Positive Subjects in Taiwan.

BACKGROUND: Mucopolysaccharidosis II (MPS II) is an X-linked disorder resulting from a deficiency in lysosomal enzyme iduronate-2-sulfatase (IDS), which causes the accumulation of glycosaminoglycans (GAGs) in the lysosomes of many tissues and organs, leading to progressive cellular dysfunction. An MPS II newborn screening program has been available in Taiwan since 2015. The aim of the current study was to collect and analyze the long-term follow-up data of the screen-positive subjects in this program. METHODS: From August 2015 to April 2022, 548,624 newborns were screened for MPS II by dried blood spots using tandem mass spectrometry, of which 202 suspected infants were referred to our hospital for confirmation. The diagnosis of MPS II was confirmed by IDS enzyme activity assay in leukocytes, quantitative determination of urinary GAGs by mass spectrometry, and identification of the IDS gene variant. RESULTS: Among the 202 referred infants, 10 (5%) with seven IDS gene variants were diagnosed with confirmed MPS II (Group 1), 151 (75%) with nine IDS gene variants were classified as having suspected MPS II or pseudodeficiency (Group 2), and 41 (20%) with five IDS gene variants were classified as not having MPS II (Group 3). Long-term follow-up every 6 months was arranged for the infants in Group 1 and Group 2. Intravenous enzyme replacement therapy (ERT) was started in four patients at 1, 0.5, 0.4, and 0.5 years of age, respectively. Three patients also received hematopoietic stem cell transplantation (HSCT) at 1.5, 0.9, and 0.6 years of age, respectively. After ERT and/or HSCT, IDS enzyme activity and the quantity of urinary GAGs significantly improved in all of these patients compared with the baseline data. CONCLUSIONS: Because of the progressive nature of MPS II, early diagnosis via a newborn screening program and timely initiation of ERT and/or HSCT before the occurrence of irreversible organ damage may lead to better clinical outcomes. The findings of the current study could serve as baseline data for the analysis of the long-term effects of ERT and HSCT in these patients.

Long-Term Cardiovascular Findings in Williams Syndrome: A Single Medical Center Experience in Taiwan.

Williams syndrome (WS) is a rare genetic disorder caused by the microdeletion of chromosome 7q11.23. Cardiovascular defects (CVDs) are the leading causes of morbidity and mortality in patients with WS. The most common CVD in patients with WS is supravalvular aortic stenosis (SVAS), which recovers spontaneously similar to branch pulmonary stenosis (PS). Recently, conventional beliefs, such as SVAS improving rather than worsening in WS, have been challenged. This study thoroughly reviews the medical records of 30 patients with a molecular diagnosis of WS. We followed up these patients at Taipei MacKay Memorial Hospital from January 1999 to December 2021. The long-term outcomes of cardiovascular lesions as well as the change in peak pressure gradient in obstructive cardiovascular lesions over time were studied. Among these 30 patients, the most common cardiovascular lesion was SVAS (50.0%), followed by branch PS (36.7%). During the follow-up period, severe SVAS was aggravated (p = 0.021). The peak pressure gradient decreased from 38.4 to 25.3 mmHg (p = 0.001) in patients with branch PS. Among patients with WS, those with severe SVAS deteriorated over time, whereas those with branch PS improved on their own. In patients with WS who presented with branch PS, no disease-specific intervention was needed.

Clinical Utility of Elosulfase Alfa in the Treatment of Morquio A Syndrome.

Mucopolysaccharidosis type IVA (MPS IVA or Morquio A) is an autosomal recessive disorder and is one of the lysosomal storage diseases. Patients with MPS IVA have a striking skeletal phenotype but normal intellect. The phenotypic continuum of MPS IVA ranges from severe and rapid progress to mild and slow progress. The diagnosis of MPS IVA is usually suspected based on abnormal bone findings and dysplasia on physical examination and radiographic investigation in the preschool years. In the past, only supportive care was available. Due to the early and severe skeletal abnormalities, the orthopedic specialist was usually the main care provider. However, patients need aggressive monitoring and management of their systemic disease. Therefore, they need an interdisciplinary team for their care, comprising medical geneticists, cardiologists, pulmonary specialists, gastroenterologists, otolaryngologists, audiologists, and ophthalmologists. After the US Food and Drug Administration approved elosulfase alfa in 2014, patients older than 5 years could benefit from this treatment. Clinical trials showed clinically meaningful improvements with once-a-week intravenous dosing (2.0 mg/kg per week), significantly improving the 6min walk test, the 3min stair climb test, and respiratory function when compared with placebo. Elosulfase alfa is well-tolerated, and there is a good response indicated by decreasing urine glycosaminoglycans.

The first mucopolysaccharidosis type VII in a Taiwanese girl: A case report and review of the literature.

The present study included the first case of mucopolysaccharidosis (MPS) type VII in Taiwan. During pregnancy, the patient was diagnosed with hydrops fetalis and had ascites aspiration 4 times. In the following years, she presented gradually with chronic lung disease, developmental delay, short stature, dysmorphic features of coarse face, macroglossia and pigeon chest with scoliosis. Upon referral at age 4 years, she had corneal clouding, mild limitation of range of motion (ROM) and hepatosplenomegaly. X-ray showed paddle ribs and dysplastic vertebral bodies. MPS was suspected and urine glycosaminoglycans (GAGs) elevated were noted. The leukocyte enzymatic analyses for MPS I, MPS II, MPS IIIB, MPS IVA, and MPS VI were all normal. Afterward, the molecular analysis showed two heterozygous genetic variants of c.104C > A and c.1454C > T in trans in the GUSB gene (NM_000181.4) which were the causes for MPS VII. Then, we checked the leukocyte ß-glucuronidase activity for MPS VII and showed extremely low, therefore confirmed the diagnosis. Clinicians should increase the awareness on the early signs of MPS to have a prompt diagnosis and offer the correct treatment like enzyme replacement therapy (ERT) as early as possible.

Wiedemann-Steiner Syndrome with a Pathogenic Variant in KMT2A from Taiwan.

Wiedemann-Steiner syndrome (WSS) is a rare genetic disorder. Patients with WSS have characteristics of growth retardation, facial dysmorphism, hypertrichosis cubiti (HC), and neurodevelopmental delays. WSS is in an autosomal dominant inherited pattern caused by a mutation of the KMT2A gene (NM_001197104.2). In this article, we discuss a 5-year-old boy who has mild intellectual disability (ID), hypotonia, HC, hypertrichosis on the back, dysmorphic facies, psychomotor retardation, and growth delay. Trio-based whole-exome sequencing (trio-WES) was carried out on this patient and his parents, confirming the variants with Sanger sequencing. Trio-WES showed a de novo mutation of the KMT2A gene (NM_001197104.2: c.4696G>A, p.Gly1566Arg). On the basis of the clinical features and the results of the WES, WSS was diagnosed. Therefore, medical professionals should consider a diagnosis of WSS if patients have growth retardation and development delay as well as hirsutism, particularly HC.

Nationwide Newborn Screening Program for Mucopolysaccharidoses in Taiwan and an Update of the "Gold Standard" Criteria Required to Make a Confirmatory Diagnosis.

Mucopolysaccharidoses (MPSs) are a group of lysosomal storage diseases (LSDs) caused by an inherited gene defect. MPS patients can remain undetected unless the initial signs or symptoms have been identified. Newborn screening (NBS) programs for MPSs have been implemented in Taiwan since 2015, and more than 48.5% of confirmed cases of MPS have since been referred from these NBS programs. The purpose of this study was to report the current status of NBS for MPSs in Taiwan and update the gold standard criteria required to make a confirmative diagnosis of MPS, which requires the presence of the following three laboratory findings: (1) elevation of individual urinary glycosaminoglycan (GAG)-derived disaccharides detected by MS/MS-based assay; (2) deficient activity of a particular leukocyte enzyme by fluorometric assay; and (3) verification of heterogeneous or homogeneous variants by Sanger sequencing or next generation sequencing. Up to 30 April 2021, 599,962 newborn babies have been screened through the NBS programs for MPS type I, II, VI, and IVA, and a total of 255 infants have been referred to MacKay Memorial Hospital for a confirmatory diagnosis. Of these infants, four cases were confirmed to have MPS I, nine cases MPS II, and three cases MPS IVA, with prevalence rates of 0.67, 2.92, and 4.13 per 100,000 live births, respectively. Intensive long-term regular physical and laboratory examinations for asymptomatic infants with confirmed MPS or with highly suspected MPS can enhance the ability to administer ERT in a timely fashion.

Otorhinolaryngological Management in Taiwanese Patients with Mucopolysaccharidoses.

Background: Mucopolysaccharidoses (MPSs) are lysosomal storage disorders wherein glycosaminoglycans accumulate because the enzymes that degrade them are insufficient. The earliest symptoms, which are the main reasons for seeking consultation, are otorhinolaryngological and commonly occur in MPS I, II, IV, and VI. This retrospective study aimed to determine the occurrence of otorhinolaryngological manifestations in MPS patients in Taiwan and to analyze the prognosis of surgical intervention, including its effect on symptoms. Methods: We reviewed 42 patients (30 males and 12 females), with a median age of 20.5 years, who had MPS (16.7% type I, 35.7% type II, 19.0% type IIIB, 21.4% type IVA, and 7.2% type VI). The following otorhinolaryngological manifestations were collected: annual number of upper respiratory tract infections (URTIs) and otitis media with effusion (OME) episodes, adenoid size, tonsillar size, and apnea-hypopnea index (AHI). Results: Among 42 patients, we found recurrent otitis media in 42.9% of the patients, hearing loss in 83.3% (mixed: 52.4%, conductive: 21.4%, and sensorineural: 9.5%), frequent URTIs in 47.6%, and obstructive sleep apnea syndrome in 35.7%. Moreover, 76% of the patients underwent ear, nose, and throat (ENT) surgery, including adenoidectomy, tonsillectomy, tympanostomy with ventilation tube insertion, tracheotomy, and supraglottoplasty. Conclusions: MPS patients had a high incidence of ENT problems. ENT surgery reduced the severity of hearing loss, degree of symptoms related to upper airway obstruction, and severity of respiratory tract and otological infections of patients with MPS.

The effects of the Otago Exercise Programme on actual and perceived balance in older adults: A meta-analysis.

OBJECTIVE: Falls are serious issues in older populations. Balance problems are a major cause of falls and may lead to fear of falling and decreased balance confidence. The Otago Exercise Programme (OEP) is an effective fall prevention program that benefits balance function and fear of falling. The primary aim of the meta-analysis was to investigate the effectiveness of the OEP intervention on actual balance performance (i.e., static, dynamic, proactive or reactive balance) and perceived balance ability (i.e., balance confidence or fear of falling) for older adults; the secondary aim was to examine which OEP protocol most improves balance in older adults. METHODS: A systematic electronic review search was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines to identify randomized controlled trials (RCTs) investigating the effects of the OEP on actual balance performance and perceived balance ability in healthy older adults, and examining which OEP training protocol and intervention format most improves balance. RESULTS: A total of 12 RCTs were included in the analyses. The OEP exerted significant effects on static balance (Hedges's g = 0.388; 95% confidence interval [CI] = 0.131 to 0.645), dynamic balance (g = -0.228; 95% CI = -0.352 to -0.1.4), proactive balance (g = 0.239; 95% CI = 0.061 to 0.416) and perceived balance (g = -0.184; 95% CI = -0.320 to -0.048) in older adults. Subgroup analysis indicated that the group format for the OEP was more effective for improving static (p = 0.008), dynamic (p = 0.004) and perceived balance (p = 0.004) than was the individual format. Sessions of >30 minutes were more effective in improving static (p = 0.007) and perceived balance (p = 0.014) than were sessions of ≤30 minutes. However, the effects of the OEP on balance were unrelated to the types of control group, training frequency and training period. DISCUSSION: The OEP is helpful for improving actual balance including static, dynamic, and proactive balance; enhancing confidence in balance control; and reducing fear of falling in older adults. In particular, administrating the OEP in a group setting in >30-minute sessions may be the most appropriate and effective exercise protocol for improving balance.

The first SHORT syndrome in a Taiwanese boy: A case report and review of the literature.

SHORT syndrome is a rare, multisystem disease named with the acronym arising from short stature, hyperextensibility of joints, ocular depression, Rieger anomaly, and teething delay. Metabolic anomalies such as insulin resistance and diabetes are also present. This disease is related to heterozygous variants in the PIK3R1 and is inherited in an autosomal-dominant manner. In this case report, we present a Taiwanese boy with SHORT syndrome who had growth retardation and dysmorphic features, including a triangular face, prominent forehead, and small chin. We performed anthropometric and laboratory measurements and imaging examinations. We noted no insulin resistance or diabetes. We performed whole exome and Sanger sequencing and confirmed the underlying genetic variant, detecting a heterozygous variant of PIK3R1 (NM_181523.3) (c.1945C > T). In a family survey, his parents indicated no similar clinical symptoms and no gene variant. This case is the first SHORT syndrome in Taiwan. Specific facial dysmorphisms of this case help us confirm the diagnosis with timely genetic testing and then we can provide appropriate management and proper care.

Increased Diagnostic Yield of Array Comparative Genomic Hybridization for Autism Spectrum Disorder in One Institution in Taiwan.

Background and Objectives: Chromosomal microarray offers superior sensitivity for identification of submicroscopic copy number variants (CNVs) and is recommended for the initial genetic testing of patients with autism spectrum disorder (ASD). This study aims to determine the diagnostic yield of array comparative genomic hybridization (array-CGH) in ASD patients from a cohort of Chinese patients in Taiwan. Materials and Methods: Enrolled in this study were 80 ASD children (49 males and 31 females; 2-16 years old) followed up at Taipei MacKay Memorial Hospital between January 2010 and December 2020. The genomic DNA extracted from blood samples was analyzed by array-CGH via the Affymetrix GeneChip Genome-Wide Human single nucleotide polymorphism (SNP) and NimbleGen International Standards for Cytogenomic Arrays (ISCA) Plus Cytogenetic Arrays. The CNVs were classified into five groups: pathogenic (pathologic variant), likely pathogenic (potential pathologic variant), likely benign (potential normal genomic variant), benign (normal genomic variant), and uncertain clinical significance (variance of uncertain significance), according to the American College of Medical Genetics (ACMG) guidelines. Results: We identified 47 CNVs, 31 of which in 27 patients were clinically significant. The overall diagnostic yield was 33.8%. The most frequently clinically significant CNV was 15q11.2 deletion, which was present in 4 (5.0%) patients. Conclusions: In this study, a satisfactory diagnostic yield of array-CGH was demonstrated in a Taiwanese ASD patient cohort, supporting the clinical usefulness of array-CGH as the first-line testing of ASD in Taiwan.

Identification and Functional Characterization of IDS Gene Mutations Underlying Taiwanese Hunter Syndrome (Mucopolysaccharidosis Type II).

Hunter syndrome (mucopolysaccharidosis II; MPS II) is caused by a defect of the iduronate-2-sulfatase (IDS) gene. Few studies have reported integrated mutation data of Taiwanese MPS II phenotypes. In this study, we summarized genotype and phenotype correlations of confirmed MPS II patients and asymptomatic MPS II infants in Taiwan. Regular polymerase chain reaction and DNA sequencing were used to identify genetic abnormalities of 191 cases, including 51 unrelated patients with confirmed MPS II and 140 asymptomatic infants. IDS activity was analyzed in individual novel IDS variants using in vitro expression studies. Nineteen novel mutations were identified, in which the percentages of IDS activity of the novel missense mutations c.137A>C, c.311A>T, c.454A>C, c.797C>G, c.817C>T, c.998C>T, c.1106C>G, c.1400C>T, c.1402C>T, and c.1403G>A were significantly decreased (p < 0.001), c.254C>T and c.1025A>G were moderately decreased (p < 0.01), and c.851C>T was slightly decreased (p < 0.05) comparing with normal enzyme activity. The activities of the other six missense mutations were reduced but were insignificant. The results of genomic studies and their phenotypes were highly correlated. A greater understanding of the positive correlations may help to prevent the irreversible manifestations of Hunter syndrome, particularly in infants suspected of having asymptomatic MPS II. In addition, urinary glycosaminoglycan assay is important to diagnose Hunter syndrome since gene mutations are not definitive (could be non-pathogenic).

An At-Risk Population Screening Program for Mucopolysaccharidoses by Measuring Urinary Glycosaminoglycans in Taiwan.

BACKGROUND: The mucopolysaccharidoses (MPSs) are a group of rare lysosomal storage disorders characterized by the accumulation of glycosaminoglycans (GAGs) and which eventually cause progressive damage to various tissues and organs. We developed a feasible MPS screening algorithm and established a cross-specialty collaboration platform between medical geneticists and other medical specialists based on at-risk criteria to allow for an earlier confirmative diagnosis of MPS. METHODS: Children (<19 years of age) with clinical signs and symptoms compatible with MPS were prospectively enrolled from pediatric clinics between July 2013 and June 2018. Urine samples were collected for a non-specific total GAG analysis using the dimethylmethylene blue (DMB) spectrophotometric method, and the quantitation of three urinary GAGs (dermatan sulfate (DS), heparan sulfate (HS), and keratan sulfate (KS)) was performed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The subjects with elevated urinary GAG levels were recalled for leukocyte enzyme activity assay and genetic testing for confirmation. RESULTS: Among 153 subjects enrolled in this study, 13 had a confirmative diagnosis of MPS (age range, 0.6 to 10.9 years-three with MPS I, four with MPS II, five with MPS IIIB, and one with MPS IVA). The major signs and symptoms with regards to different systems recorded by pediatricians at the time of the decision to test for MPS were the musculoskeletal system (55%), followed by the neurological system (45%) and coarse facial features (39%). For these 13 patients, the median age at the diagnosis of MPS was 2.9 years. The false negative rate of urinary DMB ratio using the dye-based method for these 13 patients was 31%, including one MPS I, two MPS IIIB, and one MPS IVA. However, there were no false negative results with urinary DS, HS and KS using the MS/MS-based method. CONCLUSIONS: We established an at-risk population screening program for MPS by measuring urinary GAG fractionation biomarkers using the LC-MS/MS method. The program included medical geneticists and other medical specialists to increase awareness and enable an early diagnosis by detecting MPS at the initial onset of clinical symptoms.

Normalization of glycosaminoglycan-derived disaccharides detected by tandem mass spectrometry assay for the diagnosis of mucopolysaccharidosis.

Mucopolysaccharidosis (MPS) is caused by the deficiency of a specific hydrolytic enzyme that catalyzes the step-wise degradation of glycosaminoglycans (GAGs). In this study, we propose an empirical method to calculate levels of GAG-derived disaccharides based on the quantity (peak areas) of chondroitin sulfate (CS) with the aim of making a diagnosis of MPS more accurate and reducing the occurrence of false positive and false negative results. In this study, levels of urinary GAG-derived disaccharides were measured in 67 patients with different types of MPS and 165 controls without MPS using a tandem mass spectrometry assay. Two different methods of reporting GAG-derived disaccharides were assessed; normalization to urinary CS (in µg/mL), and normalization to µg/mg creatinine. CS-normalization yielded more consistent values than creatinine-normalization. In particular, levels of urinary dermatan sulfate (DS), heparan sulfate (HS), and keratan sulfate (KS) significantly varied because of changes in urine creatinine levels, which were proportional to age but inversely proportional to DS, HS, and KS measurements. Using CS-normalization revealed the actual status of DS, HS, and KS without the influence of factors such as age, urine creatinine, and other physiological conditions. It could discriminate between the patients with MPS and controls without MPS, and also to evaluate changes in GAG levels pre- and post-enzyme replacement therapy.