Study on genetic etiology of two patients with mucopolysaccharidosis using whole-exome sequencing / 中华内分泌代谢杂志

Objective:To explore the underlying genetic cause in two patients with mucopolysaccharidosis(MPS)using the whole-exome sequencing.Methods:Genomic DNA was extracted from the peripheral blood of two patients with MPS and their family members. Sanger sequencing and pedigree verification were performed on the pathogenic variants filtered by whole-exome sequencing. The function of the mutation sites was analyzed by bioinformatics software. The effect of the splice mutation on mRNA was further determined by reverse transcription-PCR(RT-PCR).Results:The proband 1 was a 25-year-old male, who carried compound heterozygous mutations of α-L-iduronidas(IDUA) gene: p. T179R and p. S633L, and was diagnosed as MPSⅠ. His mother and sister carried heterozygous p. T179R, while his father carried heterozygous p. S633L, consistent with the autosomal recessive inheritance pattern. The proband 2 was a 3-year-old male, who was hemizygous for IVS 6-8A>G of iduronate-2-sulfatase(IDS) gene. His mother and grandmother were heterozygous for this mutation, consistent with the X-linked recessive inheritance. The proband 2 was diagnosed as MPSⅡ. Sequencing of RT-PCR products showed that the IVS 6-8A>G mutation activated an upstream cryptic splice-site in intron 6, leading to 7 nucleotide insertion in exon 7, frameshift, and shorter peptide chain.Conclusion:In this study, IDUA p. T179R and p. S633L, and IDS IVS 6-8A>G mutations were found in two patients with MPS by whole exome sequencing, which further expanded the genotypic and phenotype spectrum of MPS.

A novel compound mutation in alpha-L-iduronidase gene causes mucopolysaccharidosis type

Mucopolysaccharidosis type I (MPSI) is a rare autosomal recessive disorder caused bymutations in alpha-L-iduronidase (IDUA) gene. IDUA contributes to the degradation of the glycosaminoglycans, including heparan sulphate and dermatan sulphate. Deficient activity of IDUA generates accumulation of glycosaminoglycans in lysosomes leading to MPS I. Here, we identified twoboys with MPS I caused by a compound heterozygote of a reported c.265C > T (p.R89W) missense mutation in exon 2 and a novel c.1633G > T (p.E545*, 109) nonsense mutation in exon 11 of IDUA gene in a Chinese family. R89 is close to the active site and its replacement will affect the structure and function of IDUA. Besides, termination from E545 deletes one of the prominent domainsand alters the spatial structure of IDUA. In conclusion, our study demonstrates a previously unrecognized mutation in IDUA gene and this report adds to the mutational spectrum observed.

Long-term restoration of alpha-L-iduronidase activity in fibroblasts from patients with mucopolysaccharidosis type I after non-viral gene transfer

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder caused by deficiency of alpha-L-iduronidase (IDUA). Limitations such as the need for weekly injections, high morbidity and mortality, and high cost of current treatments show that new approaches to treat this disease are required. In this study, we aimed to correct fibroblasts from a patient with MPS I using non-viral gene therapy. Using a plasmid encoding the human IDUA cDNA, we achieved stable high IDUA levels in transfected fibroblasts up to 6 months of treatment. These results serve as proof of concept that a non-viral approach can correct the enzyme deficiency in cells of patients with lysosomal storage disorders, which can be used as a research tool for a series of disease aspects. Future studies should focus on showing if this approach can be useful in small animals and clinical trials (AU)

Detecting multiple lysosomal enzymes in dried blood spots by tandem mass spectrometry / 中华检验医学杂志

Objective Establish a method for measuring the activities of Galactocerebrosidase (GALC), α-Glucosidase(GAA), α-Galactosidase (GLA) and α-L-Iduronidase (IDUA) in dried blood spots specimen by tandem mass spectrometry ( MS/MS ).Methods A total of 2175 dried blood spot samples forinborn errors of metabolism in neonatalscreening center of Shanghai Xinhua hospital were collected in July and November, 2013.And twenty dried blood spot samples from patients withlysosomalstorage disorders( LSDs) of Shanghai Xin Hua Hospital were collected from September 2012 to January 2014.The extraction of DBS was incubated with enzyme substrates and internal standards.After liquid-liquid and solid-phase extraction, the extraction solution was dried under nitrogen and reconstituted.Then enzyme reaction products and internal standards were analyzed by MS/MS.Linearity, precision, accuracy and the limit of detection were evaluated.2175 dried blood spot samples were detected to establish the normal reference range for the activities of four enzymes according to 0.5th to 99.5th percentiles.20 specimens from patients withLSDs were detected to verify the reference range inclinical judgment.Results The intraassay and interassay precisions ranged from 1.7%to 11.8%, and the intraassay and interassay accuracies ranged from 85%to 115%.The linear coefficients for measured concentration of enzyme products/internal standards and theoretical concentration were 0.997-0.999.The limits of detection forGALC, GAA, GLA and GLA were 0.03 μmol/(L· h), 0.09 μmol/(L· h), 0.12 μmol/(L· h) and 0.16 μmol/(L· h) .The normal reference values for GALC, GAA, GLA and GLAwere 0.51-8.51μmol( L· h) ,1.99-22.22μmol/( L· h),1.68-41.59 μmol/(L· h) and 2.36-19.21 μmol/(L· h).The enzymes of 20 patients with LSDs were remarkably decreased compared to the normal range.The Krabbe, Pompe, Fabry, MPSⅠpatients can be effectively detected by this MS/MS method.Conclusions A MS/MS method for measuring GALC, GAA, GLA and IDUA enzyme activities in DBShas been established.

Tratamiento de mucopolisacaridosis tipo I con trasplante de células madre de sangre de cordón umbilical de donante no emparentado: informe del primer caso exitoso en Colombia / Treatment of mucopolysaccharidosis I with cord blood stem cell transplantation of unrelated donor: report of first successful case in Colombia

Resumen: se presenta el primer caso exitoso en Colombia de trasplante de células madre de sangre de cordón umbilical no relacionadas, en un niño de 30 meses de edad con diagnóstico de mucopolisacaridosis tipo I. El paciente fue recibido a los seis meses de edad por presentar signos y síntomas típicos de la enfermedad, por lo que se realizó confirmación diagnóstica por bioquímica y se determinó la mutación genética. Se inició terapia de reemplazo enzimático con laronidasa a los 13 meses de edad y se llevó a cabo un trasplante de sangre de cordón umbilical de un donante no emparentado a los 30 meses, alcanzando una sobrevida superior a los tres años con mejoría en el neurodesarrollo y cambios fenotípicos marcados, sin evidencia de cifosis, macrocefalia y macroglosia, entre otros. El control ecocardiográfico actual es normal, sin manejo farmacológico, evidencia de cifosis, macrocefalia o macroglosia. Como se reporta en la literatura, el trasplante de células madre de sangre de cordón umbilical de donante no emparentado es una alternativa efectiva y segura en el tratamiento de esta enfermedad.

Abstract: here we present the first successful case in Colombia of transplantation of unrelated cord blood stem cell transplantation in a 30-month-old boy diagnosed with mucopolysaccharidosis type I. Patient was received at the age of six months showing typical signs and symptoms of the disease. Biochemical diagnosis was confirmed and the genetic mutation was determined. Patient began enzymereplacement therapy with laronidase at the age of 13 months and, at the age of 30 months he underwent cord blood stem cell transplantation. The boy reaching more than three years of survival with neurologic progression with marked phenotypic changes, decrease of coarse facies, active, walking without help, with normal echocardiography results without medication, no evidence of kyphosis, macrocephaly and macroglossia. In this case, it is evident that transplantation of unrelated hematopoietic stem cells from cord blood is an effective and safe alternative in treating Hurler syndrome.

A Simple and Rapid Method Based on Liquid Chromatography-Tandem Mass Spectrometry for the Measurement of alpha-L-Iduronidase Activity in Dried Blood Spots: An Application to Mucopolysaccharidosis I (Hurler) Screening

BACKGROUND: We developed an analytical method to measure alpha-L-iduronidase (IDUA) activity in dried blood spots. This was achieved by using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) with electrospray ionization in the positive ion mode. METHODS: Chromatographic separation was completed using mobile phase involving water-formic acid and acetonitrile-formic acid over 2.8 min of run time on a column with a Kinetex XB-C18 (Phenomenex, USA). The detection of column effluent was performed using a Xevo TQ-S triple quadrupole mass spectrometer (Waters, USA) in the multiple-reaction monitoring mode. This method was verified with blank and control samples at four activity levels: base, low, medium, and high. Control materials were provided from Centers for Disease Control and Prevention (CDC). RESULTS: Intra- and inter-day precisions were between 2.6% and 16.5% and between 7.9% and 17.0%, respectively. A correlative regression study on the IDUA activity in CDC-control samples performed to assess the validity of the developed method showed a highly significant linear association (r2=0.9976) between the calculated and CDC-reported values and an obvious difference in activity among the four levels. This reliable analytical method was applied to mucopolysaccharidosis I (Hurler) screening of patients under treatment (n=4) and in normal controls (n=129). IDUA activity ranged from 8.98 to 77.12 micromol/hr/L) in normal controls, and patients undergoing medical treatment showed low IDUA activity. CONCLUSIONS: This method had advantages of simplicity, rapid sample preparation, and liquid chromatographic separation, which efficiently inhibited ionization suppression induced by matrix effects in mass spectrometric detection.

Three novel α-L-iduronidase mutations in 10 unrelated Chinese mucopolysaccharidosis type I families

Mucopolysaccharidosis type I (MPS I) arises from a deficiency in the α-L-iduronidase (IDUA) enzyme. Although the clinical spectrum in MPS I patients is continuous, it was possible to recognize 3 phenotypes reflecting the severity of symptoms, viz., the Hurler, Scheie and Hurler/Scheie syndromes. In this study, 10 unrelated Chinese MPS I families (nine Hurler and one Hurler/Scheie) were investigated, and 16 mutant alleles were identified. Three novel mutations in IDUA genes, one missense p.R363H (c.1088G > A) and two splice-site mutations (c.1190-1G > A and c.792+1G > T), were found. Notably, 45 percent (nine out of 20) and 30 percent (six out of 20) of the mutant alleles in the 10 families studied were c.1190-1G > A and c.792+1G > T, respectively. The novel missense mutation p.R363H was transiently expressed in CHO cells, and showed retention of 2.3 percent IDUA activity. Neither p.W402X nor p.Q70X associated with the Hurler phenotype, or even p.R89Q associated with the Scheie phenotype, was found in this group. Finally, it was noted that the Chinese MPS I patients proved to be characterized with a unique set of IDUA gene mutations, not only entirely different from those encountered among Europeans and Americans, but also apparently not even the same as those found in other Asian countries.

Identification of mutation in the ?-L-iduronidase gene (IDUA) in Hurler syndromes in Chinese populations / 中国病理生理杂志

AIM: To investigate the mutation type in the IDUA gene of Liaoning district mucopolysaccharidosis I (MPS-I) patients. METHODS: The mutation type and polymorphism site in the IDUA gene of Liaoning district MPS-I patients were detected by PCR-RFLP, SSCP and DNA sequencing. RESULTS: ① There is a new mutation (1278-g-a) in the IDUA gene of Liaoning district MPS-I patients. ② There is no the common mutation (W402X and Q70X) of European patients and the common mutation (R89Q) of Japanese patients in the 10 families we studied. CONCLUSION: The mutation type in the IDUA gene of Liaoning district MPS-I patients is different from that of other countries and districts.

The mutation of ?-L-iduronidase gene for mucopolysaccharidosis type I in Liaoning district populations / 中国病理生理杂志

AIM: To investigate the mutatation type and polymorphism site in the ?-L-iduronidase (IDUA) gene of Liaoning district MPS-I patients. METHODS: The mutation type and polymorphism site in the IDUA gene of Liaoning district mucopolysaccharidosis type I (MPS-I) patients were detected by PCR-SSCP and DNA sequencing. RESULTS: ① 2 new mutations: R363H, 880+g-c in the IDUA gene of Liaoning district MPS-I patients were found. ② There were 3 polymorphism sites: R105Q、L118 and A361T in the IDUA gene of Liaoning district MPS-I patients. CONCLUSIONS: The mutation type in the IDUA gene of Liaoning district MPS-I patients is different from that of other countries and districts, while the polymorphism site in the IDUA gene of Liaoning district MPS-I patients is the same as that of other countries. [