A novel splice site mutation in the PAX6 gene in a Korean family with isolated aniridia.

Aniridia is a rare congenital ocular disorder of complete or partial iris hypoplasia. Frequently associated ocular changes include corneal abnormalities, cataract, glaucoma, and foveal hypoplasia. In most cases, aniridia is caused by decreased dosage of the paired box 6 (PAX6) gene, which is located in chromosome 11p13. We report the case of a Korean family with isolated aniridia inherited in an autosomal dominant manner. The proband was a one-month-old boy. He presented with bilateral complete aniridia and congenital glaucoma. His four-year-old sister had bilateral complete aniridia, glaucoma, and a corneal ulcer. His father had bilateral microcornea and cataract without aniridia. Using PAX6 sequencing analysis, we identified a deletion at the splice donor site of intron 8 in the proband (c.357+1delG). To our knowledge, this variant has not been previously described.

Osteogenesis imperfecta Type I caused by a novel mutation in the start codon of the COL1A1 gene in a Korean family.

Osteogenesis imperfecta (OI) comprises a heterogeneous group of disorders characterized by susceptibility to bone fractures ranging in severity from perinatal death to a subtle increase in fracture frequency. We report the case of a patient who appeared healthy at birth and did not experience any fractures until 12 months of age. We observed blue sclera, frequent fractures without commensurate trauma, nearly normal stature, the absence of dentinogenesis imperfecta, no bony deformity, and no limitation of mobility in the patient--all characteristics suggestive of OI Type I. The patient's mother also had blue sclera and a history of frequent fracture episodes until the age of 15 years. A novel COL1A1 missense mutation (c.2T>G) disrupting the start codon of the gene (ATG to AGG (Met1Arg)) was found in the patient and his mother.

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.

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.

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.

Impact of enzyme replacement therapy on linear growth in Korean patients with mucopolysaccharidosis type II (Hunter syndrome).

Hunter syndrome (or mucopolysaccharidosis type II [MPS II]) arises because of a deficiency in the lysosomal enzyme iduronate-2-sulfatase. Short stature is a prominent and consistent feature in MPS II. Enzyme replacement therapy (ERT) with idursulfase (Elaprase®) or idursulfase beta (Hunterase®) have been developed for these patients. The effect of ERT on the growth of Korean patients with Hunter syndrome was evaluated at a single center. This study comprised 32 patients, who had received ERT for at least 2 yr; they were divided into three groups according to their ages at the start of ERT: group 1 (<6 yr, n=14), group 2 (6-10 yr, n=11), and group 3 (10-20 yr, n=7). The patients showed marked growth retardation as they got older. ERT may have less effect on the growth of patients with the severe form of Hunter syndrome. The height z-scores in groups 2 and 3 revealed a significant change (the estimated slopes before and after the treatment were -0.047 and -0.007, respectively: difference in the slope, 0.04; P<0.001). Growth in response to ERT could be an important treatment outcome or an endpoint for future studies.

Genotype-phenotype correlation in 27 pediatric patients in congenital adrenal hyperplasia due to 21-hydroxylase deficiency in a single center.

PURPOSE: The purpose of the study was to evaluate endocrine patterns of patients with congenital adrenal hyperplasia and each gene mutation and to analyze the correlation between each phenotype and genotype. METHODS: This was a retrospective study of the patients with congenital adrenal hyperplasia in the pediatric outpatient clinic at the Samsung Medical Center from November 1994 to December 2012. We analyzed the medical records of 27 patients (male, 19; female, 8) with congenital adrenal hyperplasia who had been diagnosed by genetic testing to have 21-hydroxylase deficiency. RESULTS: In genetic analysis of 54 alleles from 27 patients, 13 types of mutations were identified. The distribution of 21-hydroxylase deficiency gene mutations revealed that intron 2 splice site (c.293-13A/C>G) mutations and large deletions were the most common, at 31.5% and 22.2% respectively, followed by p.I173N, p.R356W, and p.I172N mutations at 11.1%, 9.3%, and 9.3%, respectively. Other mutations were observed at 1.9-3.7%. No novel mutations were detected. CONCLUSION: The analysis of 54 alleles revealed 13 types of mutation. The salt wasting form showed a good correlation between genotype and phenotype, but the simple virilizing and nonclassic forms showed inconsistencies between genotype and phenotype. The distribution of CYP21A2 mutations was evaluated for 21-hydroxylase deficiency patients from a single center. This study provides limited data on mutation spectrum and genotype-phenotype correlation of 21-hydroxylase deficiency in Korea.