Search

Objective: The study aimed to evaluate the epidemiological, clinical, and molecular data of mucopolysaccharidosis type II (MPS II) patients and their outcomes using the national registry of patients in the Russian Federation (RF). Materials and Methods: In the retrospective cohort study, the authors included data from the Russian national registry of MPS II. Results: The prevalence of MPS II in RF is 0.62 per 100 000 live births or 0.09 per 100 000 population with the majority of patients in the Central (n = 36) and the Volga Federal District (n = 35). Males were 157 (99.4%), positive MPS II family history had 47 (29.7%) patients. The median age of the first symptoms was 1.8 (0.8-2.6) years, ranging from 0.1 to 19 years, and the age of diagnosis was 4.0 (2.5; 5.9) years, ranging from 0.1 to 38.9 years. A genetic study was available for the analysis in 116 (73.4%) patients. Single nucleotide variants in the IDS gene were found in 98/116 (84.5%) patients, and 18 further patients (15.5%) had gross rearrangements. About 59/98 (60.2%) patients had missense, 15/98 (15.3%) had frame-shift variants, 12/98 (12.2%) had splice site, and 11/98 (11.2%) had nonsense variants. One (1.0%) patient out of 98 patients had a small deletion. Pathogenic, likely pathogenic variants, and variants with uncertain significance were found in 54 (55.1%), 36 (36.7%), and 8 (8.2%) patients, respectively. About 138 (87.3%) patients received enzyme replacement therapy. Conclusion: The prevalence of MPS II in the RF is higher than that in some European countries and closer to the Asian population. The registry is a convenient tool for disease epidemiology and monitoring. [ABSTRACT FROM AUTHOR]

Mucopolysaccharidosis II (MPS II) is a lysosomal storage disease caused by a deficiency in iduronate-2-sulfatase (IDS), leading to the accumulation of dermatan sulfate and heparan sulfate in lysosomes. Traditionally, genotyping of the IDS gene has been conducted through exome sequencing, which fails to detect inversion variants. Consequently, when no pathogenic variants are detected in exons, additional PCR-based analysis is required. Herein, we introduce a rapid genotyping technique method using long-range PCR for MPS II patients. We successfully identified an inversion variant and confirmed the sequences of the inversion regions. We also confirmed that the pathogenic variant in the patient originated de novo. These findings suggest that long-range PCR genotyping can identify inversion variants more rapidly compared to the previous PCR-based methods, making it a valuable tool for newborn screening (NBS) and genetic diagnosis.

Mucopolysaccharidosis type II or Hunter syndrome is a hereditary, progressive disease that occurs due to the deposition of acidic glucosaminoglycans in lysosomes, due to hereditary deficits of specific degradation enzymes. A two-year-old boy was hospitalized and diagnosed with macrocephaly, hepatomegaly and at the age of four, an iduronate 2-sulfatase (IDS) gene analysis was performed and a mutation on the 3rd exon (c.262C>T, p.R88C) on the X chromosome was determined. Only four years after the diagnosis of Hunter syndrome, the boy begins to receive enzyme therapy - the drug Elaprase. During the period of receiving therapy, the boy's progression of the disease was significantly reduced.

Abstract Background Single amino acid substitutions in the Iduronate-2-sulfatase enzyme result in destabilization of the protein and cause a genetic disorder called Hunter syndrome. To gain functional insight into the mutations causing Hunter syndrome, various bioinformatics tools were employed, and special significance is given to molecular docking. Results In-silico tools available online for preliminary analysis including SIFT, PolyPhen 2.0, etc., were primarily employed and have identified 51 Non-synonymous Single Nucleotide Polymorphisms (ns-SNPs) as possibly deleterious. Further, modelling and energy minimization followed by Root Mean Square Deviation (RMSD) calculation has labelled 42 mutations as probably deleterious ns-SNPs. Later, trajectory analysis was performed using online tools like PSIPRED, SRide, etc., and has predicted six ns-SNPs as potentially deleterious. Additionally, docking was performed, and three candidate ns-SNPs were identified. Finally, these three ns-SNPs were confirmed to play a significant role in causing syndrome through root mean square fluctuation (RMSF) calculations. Conclusion From the observed results, G134E, V503D, and E521D were predicted to be candidate ns-SNPs in comparison with other in-silico tools and confirmed by RMSF calculations. Thus, the identified candidate ns-SNPs can be employed as a potential genetic marker in the early diagnosis of Hunter syndrome after clinical validation.

Mucopolysaccharidosis type II or Hunter syndrome is a hereditary, progressive disease that occurs due to the deposition of acidic glucosaminoglycans in lysosomes, due to hereditary deficits of specific degradation enzymes. A two-year-old boy was hospitalized and diagnosed with macrocephaly, hepatomegaly and at the age of four, an iduronate 2-sulfatase (IDS) gene analysis was performed and a mutation on the 3rd exon (c.262C>T, p.R88C) on the X chromosome was determined. Only four years after the diagnosis of Hunter syndrome, the boy begins to receive enzyme therapy - the drug Elaprase. During the period of receiving therapy, the boy's progression of the disease was significantly reduced. [ABSTRACT FROM AUTHOR]

Mucopolysaccharidosis type II is an X-linked lysosomal storage disorder caused by mutations in the IDS gene that encodes the iduronate-2-sulfatase enzyme. The IDS gene is located on the long arm of the X-chromosome, comprising 9 exons, spanning approximately 24 kb. The analysis of carriers, in addition to detecting mutations in patients, is essential for genetic counseling, since the risk of recurrence for male children is 50%. Mosaicism is a well-known phenomenon described in many genetic disorders caused by a variety of mechanisms that occur when a mutation arises in the early development of an embryo. Sanger sequencing is limited in detecting somatic mosaicism and sequence change levels of less than 20% may be missed. The Next Generation Sequencing (NGS) has been increasingly used in diagnosis. It is a sensitive and fast method for the detection of somatic mosaicism. Compared to Sanger sequencing, which represents a cumulative signal, NGS technology analyzes the sequence of each DNA read in a sample. NGS might therefore facilitate the detection of mosaicism in mothers of MPS II patients. The aim of this study was to reanalyze, by NGS, all MPS II mothers that showed to be non-carriers by Sanger analysis. Twelve non-carriers were selected for the reanalysis on the Ion PGM and Ion Torrent S5 platform, using a custom panel that includes the IDS gene. Results were visualized in the Integrative Genomics Viewer (IGV). We were able to detected the presence of the variant previously found in the index case in three of the mothers, with frequencies ranging between 13 and 49% of the reads. These results suggest the possibility of mosaicism in the mothers. The use of a more sensitive technology for detecting low-level mosaic mutations is essential for accurate recurrence-risk estimates. In our study, the NGS analysis showed to be an effective methodology to detect the mosaic event.

Abstract Background Hunter syndrome (mucopolysaccharidosis type II) is a recessive X-linked disorder due to mutations in the iduronate 2-sulfatase (IDS) gene. The IDS gene encodes a lysosomal enzyme, iduronate 2-sulfatase. The disease occurs almost exclusively in males. However, in the literature, 12 cases of the disease in females are known due to structural anomalies, a non-random chromosome X inactivation or chromosome X monosomy. The purpose of this article is to demonstrate a rare case of Hunter syndrome in a girl caused by a mutation in the IDS gene inherited from the mother and the presence of chromosome X of paternal origin, partially deleted in the long arm region - 46,X,del(X)(q22.1). Case presentation Girl M., 4 years old, entered the hospital with growth retardation, pain in the lower limbs, and joint stiffness, noted from the age of 18 months. After the karyotype analysis, which revealed a partial deletion of the long arm of chromosome X - 46, X, del (X) (q 22.1), Turner syndrome was diagnosed. However, due to the hurler-like facial phenotype, Hurler syndrome or type I mucopolysaccharidosis (MPS) was suspected. The study of lysosomal enzymes showed normal alpha-L-iduronidase activity and a sharp decrease in the activity of iduronate sulfatase in the blood: 0.001 μM/l/h, at a rate of 2.5–50 μM/l/h. Molecular genetic analysis revealed a hemizygous deletion in the IDS gene, which was not registered in the international Human Gene Mutation Database (HGMD) professional. This deletion was not detected in the girl’s father, but was detected in her mother in the heterozygous state. Conclusions Thus, the girl confirmed comorbidity - Turner syndrome with a partial deletion of the long arm of chromosome X of paternal origin, affecting the Xq28 region (localization of the IDS gene), and Hunter syndrome due to a deletion of the IDS gene inherited from the mother. The structural defect of chromosome X in the girl confirmed the hemizygous state due to the mutation in the IDS gene, which has led to the formation of the clinical phenotype of Hunter syndrome.

A case-control study was designed to investigate the association Mucopolysaccharidosis (MPSII) is described as a metabolic disorder resulting from an enzymatic failure causing from mutations in IDS gene, MPSII is divided into two forms; mild and severe. The first form does not affect intelligence and patients show no neurologic involvements, usually survive for the fourth decade of life. In patients with severe form, death mostly occurs due to neurologic involvement during the second decade of life. We reported a case, a 31-year-old patient, clinically suspicious to MPSII which was primarily diagnosed by the presence of the increased levels of dermatan and heparan sulfate in urine and I2S deficiency in plasma. Whole exome sequencing was utilized to detect the disease-causing variant in our patient. A de novo mutation (c.253G>A, (p.A85T) in exon 3 of the IDS gene was identified, which probably can describe the mild form of MPSII and clinical manifestations observed in the patient. [ABSTRACT FROM AUTHOR]

Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is an inborn error of metabolism due to lysosomal accumulation, with a recessive inheritance pattern linked to the X chromosome. It is caused by a deficiency in the activity of the lysosomal enzyme iduronate-2-sulfatase encoded by the IDS gene. Iduronate-2-sulphatase enzyme activity in plasma was measured and the IDS gene was analysed in genomic DNA by automated direct sequencing. Enzyme activity was 1.2 μmol/l/h (reference value: >2 μmol/l/h), while the molecular analysis detected the mutation c.1403G>A (p.R468Q), confirming the diagnosis of MPS II. In conclusion, since here in Mexico there are few groups dedicated to this family of diseases, we must emphasise the need to keep up to date and create expert teams of doctors and scientists specialised in inborn errors of metabolism.

Objective: Mucopolysaccharidosis II (MPS II), also known as Hunter syndrome, is a rare, recessive, X-linked lysosomal storage disorder caused by a deficiency of lysosomal enzyme iduronate-2-sulfatase (IDS), encoded by IDS gene. I2S plays an important role in the lysosomal degradation of dermatan sulfate and heparan sulfate, with I2S deficiency leading to the accumulation of these glycosaminoglycans in the tissues. Materials and Methods: Exon-specific analyses of IDS exon 8 from eight Indonesian patients with MPS II from Cipto Mangunkusumo Hospital, Jakarta, Indonesia, were performed using polymerase chain reaction and sequencing-based methods. Results: Two novel mutations and a deletion variant of exon 8 were identified among the patients. A single-nucleotide deletion variant (c.1023delA), causing a frameshift in the corresponding amino acid sequence (p.Glu341AspfsTer19), was observed in all patients. In addition, a novel missense mutation (c.1033T>C) resulting in a tryptophan to arginine substitution (p.Trp345Arg), along with a single-nucleotide deletion (c.1041delA) resulting in a second frameshift in the amino acid sequence (p.Lys347AsnfsTer13), was also observed in one patient. Conclusion: This study provides the first mutation analysis of exon 8 of IDS and successfully identified mutations within the IDS gene that may be associated with MPS II. These findings will be added to the IDS gene profile database and may help in the diagnosis of MPS II in future. [ABSTRACT FROM AUTHOR]

Mucopolysaccharidosis II is a lysosomal storage disorder caused by mutations in the IDS gene, including exonic alterations associated with aberrant splicing. In the present work, cell-based splicing assays were performed to study the effects of two splicing mutations in exon 3 of IDS , i.e., c.241C > T and c.257C > T, whose presence activates a cryptic splice site in exon 3 and one in exon 8, i.e., c.1122C > T that despite being a synonymous mutation is responsible for the creation of a new splice site in exon 8 leading to a transcript shorter than usual. Mutant minigene analysis and overexpression assays revealed that SRSF2 and hnRNP E1 might be involved in the use and repression of the constitutive 3′ splice site of exon 3 respectively. For the c.1122C > T the use of antisense therapy to correct the splicing defect was explored, but transfection of patient fibroblasts with antisense morpholino oligonucleotides (n = 3) and a locked nucleic acid failed to abolish the abnormal transcript; indeed, it resulted in the appearance of yet another aberrant splicing product. Interestingly, the oligonucleotides transfection in control fibroblasts led to the appearance of the aberrant transcript observed in patients' cells after treatment, which shows that the oligonucleotides are masking an important cis -acting element for 5′ splice site regulation of exon 8. These results highlight the importance of functional studies for understanding the pathogenic consequences of mis-splicing and highlight the difficulty in developing antisense therapies involving gene regions under complex splicing regulation. [ABSTRACT FROM AUTHOR]

Abstract: Background: Hunter syndrome (mucopolysaccharidosis type II) is an X-linked recessive lysosomal storage disease caused by a defect of the iduronate-2-sulfatase (IDS) gene. The result is impaired IDS enzyme function. Methods: To characterize the biochemical and molecular defects in IDS-deficient patients and their families, we measured IDS enzyme activity by fluorimetric enzyme assay and identified the IDS gene mutations in 14 unrelated Taiwanese patients with varying clinical phenotypes. In addition, haplotype analysis was also performed. Results: Three novel (IVS2+1G>C, 1055del12, and G489D) and 7 previously reported (N63K, P228L, K347E, R468Q, R468W, I485R, and 1241delAG) mutations were found. Together R468Q and R468W account for 42.8% mutations found in our patients. Haplotype analysis using IDS flanking markers DXS1113 and DXS1123 revealed that the unrelated R468Q alleles were independent in origin whereas the unrelated R468W alleles are probably of the same origin. The R468Q mutation in patient 1150 and I485R mutation in patient 710 occurred de novo in male meioses. Once the mutation in a family was identified, restriction analysis was also performed for rapid diagnosis of female carriers in 8 families. Leukocyte IDS measurement revealed significantly wide range of IDS activity in normal controls and MPS II carriers (19.2∼70.6 vs. 8.4∼26.6 nmol/h/mg cell protein). The average leukocyte IDS activity of normal controls (n =43) was 43.9±13.3 nmol/h/mg protein, whereas patients with MPS II (n =14) had <5% of mean normal IDS activity (0.9±0.6 nmol/h/mg protein), and carriers (n =13) had a mean activity of 17.5 (±5.7) nmol/h/mg protein. The mean leukocyte IDS activity in female carriers was less than a half of the normal level. Conclusion: Due to a small overlapping range of normal and carriers, the level of enzyme activity cannot be used alone for carrier detection. [Copyright &y& Elsevier]

Mucopolysaccharidosis type II (MPS II) is an X-linked inherited disease caused by pathogenic variants in the IDS gene, leading to deficiency of the lysosomal enzyme iduronate-2-sulfatase and consequent widespread storage of glycosaminoglycans, leading to several clinical consequences, with progressive manifestations which most times includes cognitive decline. MPS II has wide allelic and clinical heterogeneity and a complex genotype-phenotype correlation. We evaluated data from 501 Brazilian patients diagnosed with MPS II from 1982 to 2020. We genotyped 280 of these patients (55.9%), which were assigned to 206 different families. Point mutations were present in 70% of our patients, being missense variants the most frequent. We correlated the IDS pathogenic variants identified with the phenotype (neuronophatic or non-neuronopathic). Except for two half-brothers, there was no discordance in the genotype-phenotype correlation among family members, nor among MPS II patients from different families with the same single base-pair substitution variant. Mothers were carriers in 82.0% of the cases. This comprehensive study of the molecular profile of the MPS II cases in Brazil sheds light on the genotype-phenotype correlation and helps the better understanding of the disease and the prediction of its clinical course, enabling the provision of a more refined genetic counseling to the affected families., (© 2021 Wiley Periodicals LLC.)

Background: Hunter syndrome (mucopolysaccharidosis type II) is a recessive X-linked disorder due to mutations in the iduronate 2-sulfatase (IDS) gene. The IDS gene encodes a lysosomal enzyme, iduronate 2-sulfatase. The disease occurs almost exclusively in males. However, in the literature, 12 cases of the disease in females are known due to structural anomalies, a non-random chromosome X inactivation or chromosome X monosomy. The purpose of this article is to demonstrate a rare case of Hunter syndrome in a girl caused by a mutation in the IDS gene inherited from the mother and the presence of chromosome X of paternal origin, partially deleted in the long arm region - 46,X,del(X)(q22.1). Case presentation: Girl M., 4 years old, entered the hospital with growth retardation, pain in the lower limbs, and joint stiffness, noted from the age of 18 months. After the karyotype analysis, which revealed a partial deletion of the long arm of chromosome X - 46, X, del (X) (q 22.1), Turner syndrome was diagnosed. However, due to the hurler-like facial phenotype, Hurler syndrome or type I mucopolysaccharidosis (MPS) was suspected. The study of lysosomal enzymes showed normal alpha-L-iduronidase activity and a sharp decrease in the activity of iduronate sulfatase in the blood: 0.001 μM/l/h, at a rate of 2.5–50 μM/l/h. Molecular genetic analysis revealed a hemizygous deletion in the IDS gene, which was not registered in the international Human Gene Mutation Database (HGMD) professional. This deletion was not detected in the girl's father, but was detected in her mother in the heterozygous state. Conclusions: Thus, the girl confirmed comorbidity - Turner syndrome with a partial deletion of the long arm of chromosome X of paternal origin, affecting the Xq28 region (localization of the IDS gene), and Hunter syndrome due to a deletion of the IDS gene inherited from the mother. The structural defect of chromosome X in the girl confirmed the hemizygous state due to the mutation in the IDS gene, which has led to the formation of the clinical phenotype of Hunter syndrome. [ABSTRACT FROM AUTHOR]