The longitudinal effect of oxcarbazepine on thyroid function in children and adolescents with epilepsy.

OBJECTIVE: Thyroid hormone abnormalities have been linked to antiseizure medications (ASMs). Oxcarbazepine is considered safer than carbamazepine because it induces the hepatic cytochrome P450 metabolic enzymes less than the carbamazepine does. However, limited data exist for the influence of oxcarbazepine on thyroid function in children and adolescents. The objective of this study was to determine the effect of oxcarbazepine on thyroid function in these patients. METHODS: A total of 162 pediatric patients with epilepsy who started oxcarbazepine for the first time between April 2003 and May 2020 were enrolled. The longitudinal effects of oxcarbazepine for thyroid functions were confirmed using general estimating equations. RESULTS: Serum triiodothyronine (T3), thyroxine (T4), and free thyroxine (fT4) levels decreased significantly during 5 years of follow-up (all p's < .001). In particular, T3 and fT4 levels were reduced steeply in the first 2 years of oxcarbazepine treatment. There was no significant change in thyroid-stimulating hormone during oxcarbazepine treatment. SIGNIFICANCE: Serum T3, T4, and fT4 levels decreased significantly during oxcarbazepine use, and this change was maintained during the treatment period. In patients receiving oxcarbazepine, it is recommended that periodic thyroid function testing should be performed, especially within the first 2 years after starting this ASM. Our results indicate that oxcarbazepine-induced hypothyroidism does not appear to be accompanied by a significant increase in TSH, and consequently might be missed if TSH alone is monitored as a measure of thyroid dysfunction.

Clinical characteristics, treatment outcomes, and occurrence of diabetes mellitus after pancreatic resection of solid pseudopapillary tumor in children and adolescents: A single institution experience with 51 cases.

BACKGROUND: Solid pseudopapillary tumors (SPTs) are rare, but they comprise the majority of pediatric pancreatic neoplasms. However, studies on these conditions in pediatric patients are lacking. The aim of this study was to investigate the clinical characteristics and treatment outcomes in children and adolescents with SPTs. METHODS: This retrospective study included 51 patients with SPTs who had undergone pancreatic tumor resection before the age of 19 years at Samsung Medical Center in Korea (from November 1994 to August 2020). We investigated the postoperative outcomes. RESULTS: Of the 51 patients with SPTs (female, 88.2%), the median age at diagnosis was 14 years (range, 8-19). The most common symptom was abdominal pain (60.8%), and 14 patients (27.5%) were asymptomatic. The median maximal tumor diameter was 7 cm (range, 1.4-14), and the pancreatic body and/or tail were involved in 68.6% of patients. The short-term complication rate was 21.5%, and the recurrence rate was 5.9%. New-onset diabetes mellitus (NODM) occurred in four patients. CONCLUSIONS: The ideal treatment for SPTs is complete resection of the tumor; however, long-term postoperative complications including NODM should be monitored carefully, particularly in children and adolescents.

Recombinant growth hormone therapy in children with Turner Syndrome in Korea: a phase III Randomized Trial.

BACKGROUND: Short stature is the most consistent characteristic feature of Turner syndrome (TS). To improve final heights of children with TS effectively, it is important to provide them with early and appropriate treatment using growth hormone (GH). The objective of this study was to assess the efficacy and safety of a new recombinant human GH, Growtropin®-II (DA-3002, Dong-A ST Co., Ltd) versus a comparator (Genotropin®, Pfizer Inc.) for Korean children with TS. METHODS: This open-label, active-controlled, parallel-group, randomized controlled phase III trial was conducted at 11 hospitals in Korea. Eligible patients (n = 58) were randomized to two groups: 1) DA-3002 group (administrated with DA-3002 at 0.14 IU [0.0450-0.050 mg] /kg/day); and 2) comparator group (administrated with the comparator at 0.14 IU [0.0450-0.050 mg] /kg/day). RESULTS: The change from baseline in annualized height velocity (HV) after a 52-week treatment period was 4.15 ± 0.30 cm/year in the DA-3002 group and 4.34 ± 0.29 cm/year in the comparator group. The lower bound of 95% two-sided confidence interval for group difference in the change of annualized HV (- 1.02) satisfied the non-inferiority margin (- 1.5). The change in height standard deviation score (HtSDS) at 52-week was 0.70 ± 0.23 for the DA-3002 group and 0.66 ± 0.39 for the comparator group, showing no significant (p = 0.685) difference between the two groups. The change of skeletal maturity defined as change in bone age/change in chronological age between the two groups was not significantly different (1.25 ± 0.58 for the DA-3002 group and 1.47 ± 0.45 for the comparator group, p = 0.134). Changes from baseline in serum insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) after 52 weeks of treatment did not differ significantly between the two groups (p = 0.565 and p = 0.388, respectively) either. The occurrence of adverse events was not statistically different between groups. CONCLUSIONS: This study demonstrates that the efficacy and safety of GH treatment with DA-3002 in children with TS are comparable with those of the comparator. It is expected to analysis the long-term effect of DA-3002 on the increase of final adult height in children with TS and possible late-onset complications in the future. TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov. ClinicalTrials.gov identifier: NCT01813630 (19/03/2013).

Identification of a novel mutation in EXT2 in a fourth-generation Korean family with multiple osteochondromas and overview of mutation spectrum.

Multiple osteochondromas (MOs) or hereditary multiple exostoses is a rare autosomal-dominant disease characterized by growths of MOs, which are benign cartilage-capped bone tumors that grow away from the growth plates. Almost 90% of MOs have a molecular explanation and 10% are unexplained. MOs are genetically heterogeneous with two causal genes on 8q24.11 (EXT1) and 11p12 (EXT2), with a higher frequency in EXT1. MO is a very rare genetic disorder, and the genotype-phenotype of MO with EXT2 mutation has not been well investigated in Korea. We present the clinical radiographic and molecular analysis of a four-generation Korean family with 11 MO-affected members (seven males and four females). The affected members from the third generation available for molecular analysis and their detailed medical histories showed moderate-to-severe phenotypes (clinical classes II-III), including bony deformities and limb misalignment with pain requiring surgical correction. The x-rays showed MOs in multiple sites. A novel EXT2 frameshift mutation (c.590delC, p.P197Qfs*73) was revealed by targeted exome sequencing in the affected members of this family. In this article, we not only expand the phenotypic-genotypic spectrum of MOs but also highlight the phenotypic heterogeneity in a family with the same mutation. In addition, we compiled the mutation spectrum of EXT2 from a literature review and identified that exon 2 of EXT2 is a mutation hot spot. Early medical attention with diagnosis of MO through careful examination of the clinical manifestations and genetic analysis can provide the opportunity to establish coordinated multispecialty management of the patient.

BGN Mutations in X-Linked Spondyloepimetaphyseal Dysplasia.

Spondyloepimetaphyseal dysplasias (SEMDs) comprise a heterogeneous group of autosomal-dominant and autosomal-recessive disorders. An apparent X-linked recessive (XLR) form of SEMD in a single Italian family was previously reported. We have been able to restudy this family together with a second family from Korea by segregating a severe SEMD in an X-linked pattern. Exome sequencing showed missense mutations in BGN c.439A>G (p.Lys147Glu) in the Korean family and c.776G>T (p.Gly259Val) in the Italian family; the c.439A>G (p.Lys147Glu) mutation was also identified in a further simplex SEMD case from India. Biglycan is an extracellular matrix proteoglycan that can bind transforming growth factor beta (TGF-ß) and thus regulate its free concentration. In 3-dimensional simulation, both altered residues localized to the concave arc of leucine-rich repeat domains of biglycan that interact with TGF-ß. The observation of recurrent BGN mutations in XLR SEMD individuals from different ethnic backgrounds allows us to define "XLR SEMD, BGN type" as a nosologic entity.

The efficacy of intracerebroventricular idursulfase-beta enzyme replacement therapy in mucopolysaccharidosis II murine model: heparan sulfate in cerebrospinal fluid as a clinical biomarker of neuropathology.

Mucopolysaccharidosis II (MPS II) is caused by a deficiency of iduronate-2-sulfatase that results in accumulation of glycosaminoglycans (GAG), including heparan sulfate (HS), which is considered to contribute to neuropathology. We examined the efficacy of intracerebroventricular (ICV) enzyme replacement therapy (ERT) of idursulfase-beta (IDS-ß) and evaluated the usefulness of HS as a biomarker for neuropathology in MPS II mice. We first examined the efficacy of three different doses (3, 10, and 30 µg) of single ICV injections of IDS-ß in MPS II mice. After the single-injection study, its long-term efficacy was elucidated with 30 µg of IDS-ß ICV injections repeated every 4 weeks for 24 weeks. The efficacy was assessed by the HS content in the cerebrospinal fluid (CSF) and the brain of the animals along with histologic examinations and behavioral tests. In the single-injection study, the 30 µg of IDS-ß ICV injection showed significant reductions of HS content in brain and CSF that were maintained for 28 days. Furthermore, HS content in CSF was significantly correlated with HS content in brain. In the long-term repeated-injection study, the HS content in the brain and CSF was also significantly reduced and correlated. The histologic examinations showed a reduction in lysosomal storage. A significant improvement in memory/learning function was observed in open-field and fear-conditioning tests. ICV ERT with 30 µg of IDS-ß produced significant improvements in biochemical, histological, and functional parameters in MPS II mice. Furthermore, we demonstrate for the first time that the HS in the CSF had significant positive correlation with brain tissue HS and GAG levels, suggesting HS in CSF as a useful clinical biomarker for neuropathology.

HDR syndrome with a novel mutation in GATA3 mimicking a congenital X-linked stapes gusher: a case report.

BACKGROUND: Hypoparathyroidism, sensorineural hearing loss, and renal disease (HDR) syndrome, also known as Barakat syndrome, is a rare genetic disorder with high phenotypic heterogeneity caused by haploinsufficiency of the GATA3 gene on chromosome 10p14-p15. For these reasons, the diagnosis of HDR syndrome is challenging and requires a high index of suspicion as well as genetic analysis. CASE PRESENTATION: A 14-month-old boy, with sensorineural hearing loss in both ears, showed typical radiological features of X-linked stapes gusher on preoperative temporal bone computed tomography (CT) for cochlear implantations. Then after his discharge from hospital, he suffered a hypocalcemic seizure and we discovered a renal cyst during investigation of hypocalcemia. He was finally diagnosed with HDR syndrome by clinical findings, which were confirmed by molecular genetic testing. Direct sequencing of the GATA3 gene showed a heterozygous 2-bp deletion (c.1201_1202delAT), which is predicted to cause a frameshift of the reading frame (p.Met401Valfs*106). CONCLUSIONS: To our knowledge, this is the first case of HDR syndrome with a novel de novo variant mimicking a congenital X-linked stapes gusher syndrome. Novel mutations and the diversity of clinical manifestations expand the genotypic and phenotypic spectrum of HDR syndrome. Diagnosis of HDR syndrome is still challenging, but clinicians should consider it in their differential diagnosis for children with a wide range of clinical manifestations including hypocalcemia induced seizures and deafness. We hope that this case will contribute to further understanding and studies of HDR-associated GATA3 mutations.

AAV8-mediated expression of N-acetylglucosamine-1-phosphate transferase attenuates bone loss in a mouse model of mucolipidosis II.

Mucolipidoses II and III (ML II and ML III) are lysosomal disorders in which the mannose 6-phosphate recognition marker is absent from lysosomal hydrolases and other glycoproteins due to mutations in GNPTAB, which encodes two of three subunits of the heterohexameric enzyme, N-acetylglucosamine-1-phosphotransferase. Both disorders are caused by the same gene, but ML II represents the more severe phenotype. Bone manifestations of ML II include hip dysplasia, scoliosis, rickets and osteogenesis imperfecta. In this study, we sought to determine whether a recombinant adeno-associated viral vector (AAV2/8-GNPTAB) could confer high and prolonged gene expression of GNPTAB and thereby influence the pathology in the cartilage and bone tissue of a GNPTAB knock out (KO) mouse model. The results demonstrated significant increases in bone mineral density and content in AAV2/8-GNPTAB-treated as compared to non-treated KO mice. We also showed that IL-6 (interleukin-6) expression in articular cartilage was reduced in AAV2/8-GNPTAB treated ML II mice. Together, these data suggest that AAV-mediated expression of GNPTAB in ML II mice can attenuate bone loss via inhibition of IL-6 production. This study emphasizes the value of the MLII KO mouse to recapitulate the clinical manifestations of the disease and highlights its amenability to therapy.

Report of 5 novel mutations of the α-L-iduronidase gene and comparison of Korean mutations in relation with those of Japan or China in patients with mucopolysaccharidosis I.

BACKGROUND: Mucopolysaccharidosis I (MPS I) is an autosomal recessive lysosomal storage disorder caused by a lack of the lysosomal enzyme α-L-iduronidase (IDUA). To date, more than 200 IDUA mutations have been reported. However, only a few types of mutations are recurrent and the frequencies of mutations differ from country to country. METHODS: We performed the IDUA mutation analysis in seven patients who were biochemically diagnosed with MPS I in the Department of Pediatrics, Samsung Medical Center, from 2009 to 2014. Here, we describe the results of the IDUA mutation analysis in seven patients with MPS I and the IDUA mutational spectrum in Korean patients with MPS I, including previous data. RESULTS: The IDUA mutations were found in all 14 alleles of 7 patients, and 11 kinds of IDUA mutations were identified. The detected mutations were five missense mutations (p.A79V, p.L346R, p.T388K, p.P496R, and p.C577Y), two nonsense mutations (p.Y618* and p.R628*), two deletions (c.683delC and c.1591delC), one splice site mutation (c.972+1G>A), and one duplication (c.613_617dup). Among these, p.T388K, p.C577Y, c.683delC, c.1591delC, and c.972+1G>A were novel mutations that have not previously been reported. After taking everything into consideration, including IDUA mutation analysis of the previously reported 10 unrelated Korean patients with MPS I, p.L346R and c.704ins5 were most commonly found in Korean patients with MPS I. However, p.W402* and p.Q70*, which have mainly been found in Caucasian patients, were not found. CONCLUSION: As a result, p.L346R and c.704ins5, which were the most common in Korea, which is geographically situated midway between China and Japan, were some of the most common mutations in China and Japan, respectively. These results are especially worthy of notice.

Acromesomelic dysplasia, type maroteaux caused by novel loss-of-function mutations of the NPR2 gene: Three case reports.

The C-type natriuretic peptide (CNP)-natriuretic peptide receptor 2 (NPR2) signaling pathway plays an important role in chondrocyte development. Homozygous loss-of-function mutations of the NPR2 gene cause acromesomelic dysplasia, type Maroteaux (AMDM). The aim of this study was to identify and characterize NPR2 loss-of-function mutations in patients with AMDM. The NPR2 gene was sequenced in three Korean patients with AMDM and functional analysis of the mutated proteins was performed in vitro. Five novel NPR2 mutations were found in the three patients: two compound heterozygous mutations [c.1231T>C (Tyr411His) and c.2761C>T (Arg921X) in Patient 1 and c.1663A>T (Lys555X) and c.1711-1G>C (M571VfsX12) in Patient 3] and a homozygous mutation [c.2762G>A (Arg921Gln) in Patient 2]. Serum NT-proCNP concentration was significantly increased in each patient compared to control subjects. Cells transfected with the expression vector of each mutant except those found in Patient 3 showed a negligible or a markedly low cGMP response after treatment with CNP. HA-tagged wild-type (wt) and HA-mutant NPR2 were expressed at comparable levels: there were two bands of ∼130 and ∼120 kDa in wt and Arg921Gln, a single ∼120 kDa band in Tyr411His, and a single ∼110 kDa in the nonsense mutant. With respect to subcellular localization, Arg921Gln as well as wt-NPR2 reached the cell surface, whereas Tyr411His and Arg921X mutants did not. The Tyr411His and Arg921X NPR2 proteins were co-localized with an endoplasmic reticulum (ER) marker and failed to traffic from the ER to the Golgi apparatus. These results are consistent with deglycosylation experiments. Tyr411His and Arg921X NPR2 are complete loss-of-function mutations, whereas Arg921Gln behaves as a receptor for CNP with limited function.

Estrogen-mediated Height Control in Girls with Marfan Syndrome.

This study evaluated the efficacy of a stepwise regimen of estradiol valerate for height control in girls with Marfan syndrome. Eight girls with Marfan syndrome who had completed estrogen treatment for height control were included. Estradiol valerate was started at a dose of 2 mg/day, and then was increased. The projected final height was estimated using the initial height percentile (on a disease-specific growth curve for Korean Marfan syndrome [gcPFHt]), and the initial bone age (baPFHt). After the estrogen treatment, the projected final height was compared to the actual final height (FHt). The median baseline chronological and bone age were 10.0 and 10.5 years, respectively. After a median of 36.5 months of treatment, the median FHt (172.6 cm) was shorter than the median gcPFHt (181.0 cm) and baPFHt (175.9 cm). In the six patients who started treatment before the age of 11 years, the median FHt (171.8 cm) was shorter than the median gcPFHt (181.5 cm) and baPFHt (177.4 cm) after treatment. The median differences between the FHt and gcPFHt and baPFHt were 9.2 and 8.3 cm, respectively. In two patients started treatment after the age of 11, the differences between FHt and gcPFHt, and baPFHt after treatment were -4 and 1.4 cm, and -1.2 and 0 cm for each case, respectively. A stepwise increasing regimen of estradiol valerate may be an effective treatment for height control in girls with Marfan syndrome, especially when started under 11 years old.

Identification and in vivo functional characterization of novel compound heterozygous BMP1 variants in osteogenesis imperfecta.

Osteogenesis imperfecta (OI) comprises a heterogeneous group of disorders that are characterized by susceptibility to bone fractures, and range in severity from a subtle increase in fracture frequency to death in the perinatal period. Most patients have defects in type I collagen biosynthesis with autosomal-dominant inheritance, but many autosomal-recessive genes have been reported. We applied whole-exome sequencing to identify mutations in a Korean OI patient who had an umbilical hernia, frequent fractures, a markedly short stature, delayed motor development, scoliosis, and dislocation of the radial head, with a bowed radius and ulna. We identified two novel variants in the BMP1 gene: c.808A>G and c.1297G>T. The former variant caused a missense change p.(Met270Val) and the latter variant caused the skipping of exon 10. The hypofunctional nature of the two variants was demonstrated in a zebrafish assay.

Safety and efficacy of enzyme replacement therapy with idursulfase beta in children aged younger than 6 years with Hunter syndrome.

Idursulfase beta (Hunterase®) has been used for enzyme replacement therapy (ERT) of patients with mucopolysaccharidosis II (MPS II, Hunter syndrome) aged 6 years or older since 2012 in Korea. The objective of this study was to evaluate the safety and efficacy of ERT with idursulfase beta in Hunter syndrome children younger than 6 years. This study was a 52-week, single center, single arm, open-label clinical trial (NCT01645189). Idursulfase beta (0.5mg/kg/week) was administered intravenously for 52 weeks. The primary endpoint was safety assessed by adverse events (AEs). Secondary endpoints included vital signs, physical examination, ECG, laboratory tests, anti-idursulfase antibodies, and efficacy represented by changes in urinary glycosaminoglycan (GAG) at week 53 from baseline. In addition, growth indices and developmental milestones (Denver II test) were evaluated as exploratory variables. All six patients experienced at least one AE. A total of 109 AEs were reported. One patient experienced a serious AE (hospitalization due to gastroenteritis) that was considered not to be treatment related. One patient (16.7%) experienced infusion-related adverse drug reactions (ADRs), developing urticaria six times and a cough five times. There were no serious ADRs and no clinically significant changes in vital signs, physical exam, laboratory parameters, or ECG. Of the six patients, four (66.7%) showed anti-idursulfase antibodies and neutralizing antibodies on at least one occasion during the study. At week 53, urinary GAG was significantly reduced by -35.1±30.6mgGAG/g creatine from baseline (P=0.038). This study indicates that the safety and efficacy of idursulfase beta are similar to those reported in Hunter syndrome patients aged 6 years or older.

Identifying the need for a multidisciplinary approach for early recognition of mucopolysaccharidosis VI (MPS VI).

Mucopolysaccharidosis VI (MPS VI, Maroteaux-Lamy syndrome) is caused by deficient activity of the enzyme, N-acetylgalactosamine-4-sulfatase, resulting in impaired degradation of the glycosaminoglycan dermatan sulfate. Patients experience a range of manifestations including joint contractures, short stature, dysostosis multiplex, coarse facial features, decreased pulmonary function, cardiac abnormalities, corneal clouding and shortened life span. Recently, clinicians from institutions in the Asia-Pacific region met to discuss the occurrence and implications of delayed diagnosis and misdiagnosis of MPS VI in the patients they have managed. Eighteen patients (44% female) were diagnosed. The most common sign presented by the patients was bone deformities in 11 patients (65%). Delays to diagnosis occurred due to the lack of or distance to diagnostic facilities for four patients (31%), alternative diagnoses for two patients (15%), and misleading symptoms experienced by two patients (15%). Several patients experienced manifestations that were subtler than would be expected and were subsequently overlooked. Several cases highlighted the unique challenges associated with diagnosing MPS VI from the perspective of different specialties and provide insights into how these patients initially present, which may help to elucidate strategies to improve the diagnosis of MPS VI.

Disease-specific growth charts for Korean infants with Prader-Willi syndrome.

Patients with Prader-Willi syndrome (PWS) present with short stature and obesity. The growth pattern of children with PWS is different from that of the healthy population. Therefore, it is not appropriate to use normal growth charts to evaluate the growth status of children with PWS. We aimed to develop disease-specific growth charts for height and weight for nongrowth hormone-treated Korean infants with PWS aged between 0 and 36 months and to use these growth charts for the evaluation and management of infants with PWS. We conducted a retrospective review of the medical records of 122 infants with genetically confirmed PWS. Data on the patients' height and weight measurements before they underwent growth hormone treatment were recorded. Disease-specific growth charts were generated and the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th centiles were calculated using the LMS (refers to λ, µ, and σ, respectively) smoothing procedure for height and weight. The disease-specific growth charts for Korean infants with PWS can be used when examining infants with PWS and when evaluating their growth at later stages for comparison purposes. They are also useful for monitoring growth patterns, nutritional assessments, and recording responses to growth hormone treatment.

Pharmacokinetics, Pharmacodynamics, and Efficacy of a Novel Long-Acting Human Growth Hormone: Fc Fusion Protein.

The current recombinant human growth hormone (rhGH) therapy requires daily subcutaneous (sc) injections, which results in poor patient compliance, especially in young children. To reduce the dosing frequency, we generated a chimeric protein of rhGH and the Fc-domain of immunoglobulin G (IgG) (rhGH-Fc). The pharmacokinetics and pharmacodynamics of sc-injected rhGH-Fc were assessed in male Sprague-Dawley rats and hypophysectomized rats, respectively. A single sc injection of rhGH-Fc at a dose of 0.2 mg/kg slowly reached a Cmax of 16.80 ng/mL and remained for 7 days with a half-life of 51.1 h. Conversely, a single sc injection of rhGH 0.2 mg/kg rapidly reached a Cmax of 46.88 ng/mL and declined with a half-life of 0.55 h to baseline values in 4 h. In the efficacy study, the sc-injected rhGH-Fc induced rapid weight gain and tibial width growth at a dose of 240 µg/animal. The effect of two injections of rhGH-Fc separated by 1 week was comparable to that of the same dose of 14 daily injections of rhGH. The rhGH-Fc is a novel candidate for long-acting rhGH therapy with more convenient weekly administration, as it reduces glomerular filtration and receptor-mediated clearance while allowing for the rapid reversal of potential adverse events.

Disease-specific Growth Charts of Marfan Syndrome Patients in Korea.

Patients with Marfan syndrome (MFS) presents with primary skeletal manifestations such as tall stature, chest wall abnormality, and scoliosis. These primary skeletal manifestations affect the growth pattern in MFS. Therefore, it is not appropriate to use normal growth charts to evaluate the growth status of MFS. We aimed to develop disease-specific growth charts for Korean MFS patients and to use these growth charts for understanding the growth patterns in MFS and managing of patients with MFS. Anthropometric data were available from 187 males and 152 females with MFS through a retrospective review of medical records. Disease-specific growth charts were generated and 3, 25, 50, 75, and 97 percentiles were calculated using the LMS (refers to λ, µ, and σ, respectively) smoothing procedure for height and weight. Comparisons between MFS patients and the general population were performed using a one-sample t-test. With regard to the height, the 50th percentile of MFS is above the normative 97th percentile in both genders. With regard to the weight, the 50 percentile of MFS is above the normative 75th percentile in male and between the normative 50th percentile and the 75th percentile in female. The disease-specific growth charts for Korean patients with MFS can be useful for monitoring growth patterns, planning the timing of growth-reductive therapy, predicting adult height and recording responses to growth-reductive therapy.

Improvement of cardiac function by short-term enzyme replacement therapy in a murine model of cardiomyopathy associated with Hunter syndrome evaluated by serial echocardiography with speckle tracking 2-D strain analysis.

Cardiac systolic function is significantly decreased in a proportion of patients with Hunter syndrome. This study was performed to evaluate the change in myocardial function associated with enzyme replacement therapy (ERT) in a mouse model of cardiomyopathy associated with Hunter syndrome. Thirty 9-week-old iduronate-2-sulfatase (IDS) knockout mice received either intravenous injection of human recombinant IDS (ERT group, N=15) or saline (control group, N=15) for 5 weeks. Echocardiography was performed at baseline and after treatment. Echocardiographic parameters of left ventricular (LV) systolic function and 2-dimensional radial and circumferential strain were assessed. At follow-up, there was a significant increase in LV fractional shortening and radial and circumferential strain in the ERT group only. Notable myocardial fibrosis was observed in the control group only. In the murine model of Hunter syndrome, ERT exerts beneficial effects on cardiac function, which can be evaluated by serial echocardiographic evaluation including 2-dimensional strain analysis.

Novel GALT variations and mutation spectrum in the Korean population with decreased galactose-1-phosphate uridyltransferase activity.

BACKGROUND: Classic galactosemia (OMIM #230400) is an autosomal recessive metabolic disorder caused by a deficiency of the galactose-1-phosphate uridyltransferase (GALT, EC2.7.7.12) protein due to mutations in the GALT gene. The aim of this study was to provide a comprehensive and updated mutation spectrum of GALT in a Korean population. METHODS: Thirteen unrelated patients screened positive for galactosemia in a newborn screening program were included in this study. They showed a reduced GALT enzyme activity in red blood cells. Direct sequencing of the GALT gene and in silico analyses were done to evaluate the impact of novel variations upon GALT enzyme activity. We also reviewed previous reports for GALT mutations in Koreans. RESULTS: We identified six novel likely pathogenic variations including three missense (p.Ala101Asp, p.Tyr165His, and p.Pro257Thr), one small deletion/insertion [c.826_827delinsAA (p.Ala276Asn)], one frameshift (p.Asn96Serfs*5), and one splicing (c.378-1G > C) likely pathogenic variations. The most frequent variation was the Duarte variant (c.940A > G, 35.3%), followed by c.507G > C (p.Gln169His, 9.6%), among 34 Korean patients. Other mutations were widely scattered. None of the eight common mutations used for targeted mutation analysis in Western countries including p.Gln188Arg, p.Ser135Leu, p.Lys285Asn, p.Leu195Pro, p.Tyr209Cys, p.Phe171Ser, c.253-2A > G, and a 5 kb deletion, had been found in Koreans until this study. CONCLUSIONS: Considering the mutation spectrum in Koreans, direct sequence analysis of entire GALT exons is recommended for accurate diagnosis. The mutations responsible for GALT deficiency in the Korean population were clearly different from those of other populations.

A biochemical and physicochemical comparison of two recombinant enzymes used for enzyme replacement therapies of hunter syndrome.

Mucopolysaccharidosis II (MPS II, Hunter syndrome; OMIM 309900) is an X-linked lysosomal storage disease caused by a deficiency in the enzyme iduronate-2-sulfatase (IDS), leading to accumulation of glycosaminoglycans (GAGs). For enzyme replacement therapy (ERT) of Hunter syndrome, two recombinant enzymes, idursulfase (Elaprase(®), Shire Human Genetic Therapies, Lexington, MA) and idursulfase beta (Hunterase(®), Green Cross Corporation, Yongin, Korea), are currently available in Korea. To compare the biochemical and physicochemical differences between idursulfase and idursulfase beta, we examined the formylglycine (FGly) content, specific enzyme activity, mannose-6-phosphate (M6P) content, sialic acid content, and in vitro cell uptake activity of normal human fibroblasts of these two enzymes.The FGly content, which determines the enzyme activity, of idursulfase beta was significantly higher than that of idursulfase (79.4 ± 0.9 vs. 68.1 ± 2.2 %, P < 0.001). In accordance with the FGly content, the specific enzyme activity of idursulfase beta was significantly higher than that of idursulfase (42.6 ± 1.1 vs. 27.8 ± 0.9 nmol/min/µg protein, P < 0.001). The levels of M6P and sialic acid were not significantly different (2.4 ± 0.1 vs 2.4 ± 0.3 mol/mol protein for M6P and 12.3 ± 0.7 vs. 12.4 ± 0.4 mol/mol protein for sialic acid). However, the cellular uptake activity of the normal human fibroblasts in vitro showed a significant difference (Kuptake, 5.09 ± 0.96 vs. 6.50 ± 1.28 nM protein, P = 0.017).In conclusion, idursulfase beta exhibited significantly higher specific enzyme activity than idursulfase, resulting from higher FGly content. These biochemical differences may be partly attributed to clinical efficacy. However, long-term clinical evaluations of Hunter syndrome patients treated with these two enzymes will be needed to demonstrate the clinical implications of significant difference of the enzyme activity and the FGly content.