The mutational spectrum of Hunter syndrome reveals correlation between biochemical and clinical profiles in Tunisian patients

Abstract Background: Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is an X-linked recessive lysosomal storage disorder resulting from deficient activity of iduronate 2-sulfatase (IDS) and the progressive lysosomal accumulation of sulfated glycosaminoglycans (GAGs). Methods: A diagnosis of MPS II or Hunter syndrome was performed based on the following approach after a clinical and paraclinical suspicion. Two biochemical and molecular tests were carried out separately and according to the availability of the biological material. Results: All patients in this cohort presented the most common MPS II clinical features. Electrophoresis of GAGs on a cellulose acetate plate in the presence of a high concentration of heparane sulfate showed an abnormal dermatan sulfate band in the patients compared with that in a control case. Furthermore, leukocyte IDS activity ranged from 0.00 to 0.75 nmol/h/mg of leukocyte protein in patients. Five previously reported mutations were identified in this study patients: one splice site mutation, c.240+1G>A; two missense mutations, p.R88P and p.G94D; a large deletion of exon 1 to exon 7; and one nonsense mutation, p.Q396*. In addition, two novel alterations were identified in the MPS II patients: one frame shift mutation, p.D450Nfs*95 and one nonsense mutation, p.Q204*. Additionally, five known IDS polymorphisms were identified in the patients: IVS3-16 (c.419-16 delT), p.T214M (c.641C>T), p.T146T (c.438 C>T), IVS5-87 (c.709-87G>A), and IVS7+38 (c.1006+38T>C). Conclusions: The high level of urine GAGs and the deficiency of iduronate 2-sulfatase activity was associated with the phenotype expression of Hunter syndrome. Molecular testing was useful for the patients’ phenotypic classification and the detection of carriers.

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The mutational spectrum of Hunter syndrome reveals correlation between biochemical and clinical profiles in Tunisian patients

10.21203/rs.2.16148/v5 ◽

2020 ◽

Author(s):

latifa chkioua ◽

Oussama Grissa ◽

Nadia Leban ◽

Moez Gribaa ◽

Hela Boudabous ◽

...

Keyword(s):

Nonsense Mutation ◽

Dermatan Sulfate ◽

Splice Site Mutation ◽

Hunter Syndrome ◽

Molecular Testing ◽

Missense Mutations ◽

Lysosomal Storage ◽

High Concentration ◽

Site Mutation ◽

Mps Ii

Abstract Background: Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is an X-linked recessive lysosomal storage disorder resulting from deficient activity of iduronate 2-sulfatase (IDS) and the progressive lysosomal accumulation of sulfated glycosaminoglycans (GAGs). Methods: A diagnosis of MPS II or Hunter syndrome was performed based on the following approach after a clinical and paraclinical suspicion. Two biochemical and molecular tests were carried out separately and according to the availability of the biological material. Results: All patients in this cohort presented the most common MPS II clinical features. Electrophoresis of GAGs on a cellulose acetate plate in the presence of a high concentration of heparane sulfate showed an abnormal dermatan sulfate band in the patients compared with that in a control case. Furthermore, leukocyte IDS activity ranged from 0.00 to 0.75 nmol/h/mg of leukocyte protein in patients.Five previously reported mutations were identified in this study patients: one splice site mutation, c.240+1G>A; two missense mutations, p.R88P and p.G94D; a large deletion of exon 1 to exon 7; and one nonsense mutation, p.Q396*. In addition, two novel alterations were identified in the MPS II patients: one frame shift mutation, p.D450Nfs*95 and one nonsense mutation, p.Q204*. Additionally, five known IDS polymorphisms were identified in the patients: c.419-16 delT, c.641C>T (p.T214M), c.438 C>T (p.T146T), c.709-87G>A, and c.1006+38T>C.Conclusions: The high level of urine GAGs and the deficiency of iduronate 2-sulfatase activity was associated with the phenotype expression of Hunter syndrome. Molecular testing was useful for the patients’ phenotypic classification and the detection of carriers.

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The mutational spectrum of Hunter syndrome reveals correlation between biochemical and clinical profiles in Tunisian patients

10.21203/rs.2.16148/v2 ◽

2019 ◽

Author(s):

latifa chkioua ◽

Oussama Grissa ◽

Nadia Leban ◽

Moez Gribaa ◽

Hela Boudabous ◽

...

Keyword(s):

Nonsense Mutation ◽

Dermatan Sulfate ◽

Splice Site Mutation ◽

Hunter Syndrome ◽

Molecular Testing ◽

Missense Mutations ◽

Lysosomal Storage ◽

High Concentration ◽

Site Mutation ◽

Mps Ii

Abstract Background: Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is an X-linked recessive lysosomal storage disorder resulting from deficient activity of iduronate 2-sulfatase ( IDS ) and the progressive lysosomal accumulation of sulfated glycosaminoglycans (GAGs). Methods: A diagnosis of MPS II or Hunter syndrome was performed based on the following approach after a clinical and paraclinical suspicion. Two biochemical and molecular tests were carried out separately and according to the availability of the biological material. Results: All patients in this cohort presented the most common MPS II clinical features. Electrophoresis of GAGs on a cellulose acetate plate in the presence of a high concentration of heparane sulfate showed an abnormal dermatan sulfate band in the patients compared with that in a control case. Furthermore, leukocyte IDS activity ranged from 0.00 to 0.75 nmol/h/mg of leukocyte protein in patients. Five previously reported mutations were identified in the study patients: one splice site mutation, c.240+1G>A; two missense mutations, p.R88P and p.G94D; a large deletion of exon 1 to exon 7; and one nonsense mutation, p.Q396*. In addition, two novel alterations were identified in the MPS II patients: one frame shift mutation, p.D450Nfs*95 and one nonsense mutation, p.Q204*. Additionally, five known IDS polymorphisms were identified in the patients: IVS3-16 (c.419-16 delT), p.T214M (c.641C>T), p.T146T (c.438 C>T), IVS5-87 (c.709-87G>A), and IVS7+38 (c.1006+38T>C). Conclusions: The high level of urine GAGs and the deficiency of iduronate 2-sulfatase activity was associated with the phenotype expression of Hunter syndrome. Molecular testing was useful for the patients’ phenotypic classification and the detection of carriers.

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The mutational spectrum of Hunter syndrome reveals correlation between biochemical and clinical profiles in Tunisian patients

10.21203/rs.2.16148/v1 ◽

2019 ◽

Author(s):

latifa chkioua ◽

Oussama Grissa ◽

Nadia Leban ◽

Moez Gribaa ◽

Hela Boudabous ◽

...

Keyword(s):

Nonsense Mutation ◽

Dermatan Sulfate ◽

Splice Site Mutation ◽

Hunter Syndrome ◽

Molecular Testing ◽

Missense Mutations ◽

Lysosomal Storage ◽

High Concentration ◽

Site Mutation ◽

Mps Ii

Abstract Background: Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is an X-linked recessive lysosomal storage disorder resulting from deficient activity of iduronate 2-sulfatase ( IDS ) and the progressive lysosomal accumulation of sulfated glycosaminoglycans (GAGs). Methods : A diagnosis of MPS II or Hunter syndrome was performed based on the following approach after a clinical and paraclinical suspicion. Two biochemical and molecular tests were carried out separately and according to the availability of the biological material. Results : All patients in this cohort presented the most common MPS II clinical features. Electrophoresis of GAGs on a cellulose acetate plate in the presence of a high concentration of heparane sulfate showed an abnormal dermatan sulfate band in the patients compared with that in a control case. Furthermore, leukocyte IDS activity ranged from 0.00 to 0.75 nmol/h/mg of proteins in the patients. Five previously reported mutations were identified in the study patients: one splice site mutation, c.240+1G>A; two missense mutations, p.R88P and p.G94D; a large deletion of exon 1 to exon 7; and one nonsense mutation, p.Q396*. In addition, two novel alterations were identified in the MPS II patients: one frame shift mutation, p.D450Nfs*95 and one nonsense mutation, p.Q204*. Additionally, five known IDS polymorphisms were identified in the patients: IVS3-16 (c.419-16 delT), p.T214 M (c.641C>T), p.T146T (c.438 C>T), IVS5-87 (c.709-87G>A), and IVS7+38 (c.1006+38T>C). Conclusions : The high level of urine GAGs and the deficiency of iduronate 2-sulfatase activity was associated with the phenotype expression of Hunter syndrome. Molecular testing was useful for the patients’ phenotypic classification and the detection of carriers.

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The mutational spectrum of Hunter syndrome reveals correlation between biochemical and clinical profiles in Tunisian patients

10.21203/rs.2.16148/v4 ◽

2020 ◽

Author(s):

Latifa Chkioua ◽

Oussama Grissa ◽

Nadia Leban ◽

Moez Gribaa ◽

Hela Boudabous ◽

...

Keyword(s):

Nonsense Mutation ◽

Dermatan Sulfate ◽

Splice Site Mutation ◽

Hunter Syndrome ◽

Molecular Testing ◽

Missense Mutations ◽

Lysosomal Storage ◽

High Concentration ◽

Site Mutation ◽

Mps Ii

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The Wiskott-Aldrich syndrome and X-linked congenital thrombocytopenia are caused by mutations of the same gene

Blood ◽

10.1182/blood.v86.10.3797.bloodjournal86103797 ◽

1995 ◽

Vol 86 (10) ◽

pp. 3797-3804 ◽

Cited By ~ 150

Author(s):

Q Zhu ◽

M Zhang ◽

RM Blaese ◽

JM Derry ◽

A Junker ◽

...

Keyword(s):

Clinical Symptoms ◽

Point Mutations ◽

Gene Mutations ◽

Exon Skipping ◽

Splice Site Mutation ◽

Missense Mutations ◽

Site Mutation ◽

Exon 2 ◽

Wiskott Aldrich Syndrome ◽

Was Gene

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, small platelets, eczema, recurrent infections, and immunodeficiency. Besides the classic WAS phenotype, there is a group of patients with congenital X-linked thrombocytopenia (XLT) who have small platelets but only transient eczema, if any, and minimal immune deficiency. Because the gene responsible for WAS has been sequenced, it was possible to correlate the WAS phenotypes with WAS gene mutations. Using a fingerprinting screening technique, we determined the approximate location of the mutation in 13 unrelated WAS patients with mild to severe clinical symptoms. Direct sequence analysis of cDNA and genomic DNA obtained from patient-derived cell lines showed 12 unique mutations distributed throughout the WAS gene, including insertions, deletions, and point mutations resulting in amino acid substitutions, termination, exon skipping, or splicing defects. Of 4 unrelated patients with the XLT phenotype, 3 had missense mutations affecting exon 2 and 1 had a splice-site mutation affecting exon 9. Patients with classic WAS had more complex mutations, resulting in termination codons, frameshift, and early termination. These findings provide direct evidence that XLT and WAS are caused by mutations of the same gene and suggest that severe clinical phenotypes are associated with complex mutations.

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Modeling Mucopolysaccharidosis Type II in the Fruit Fly by Using the RNA Interference Approach

Life ◽

10.3390/life10110263 ◽

2020 ◽

Vol 10 (11) ◽

pp. 263

Author(s):

Laura Rigon ◽

Nicole Kucharowski ◽

Franka Eckardt ◽

Reinhard Bauer

Keyword(s):

Rna Interference ◽

Enzymatic Activity ◽

Dermatan Sulfate ◽

Fruit Fly ◽

Neurological Involvement ◽

Mucopolysaccharidosis Type ◽

Type Ii ◽

Lysosomal Storage ◽

Mucopolysaccharidosis Type Ii ◽

Mps Ii

Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disorder that occurs due to the deficit of the lysosomal enzyme iduronate 2-sulfatase (IDS) that leads to the storage of the glycosaminoglycan heparan- and dermatan-sulfate in all organs and tissues. It is characterized by important clinical features and the severe form presents with a heavy neurological involvement. However, almost nothing is known about the neuropathogenesis of MPS II. To address this issue, we developed a ubiquitous, neuronal, and glial-specific knockdown model in Drosophila melanogaster by using the RNA interference (RNAi) approach. Knockdown of the Ids/CG12014 gene resulted in a significant reduction of the Ids gene expression and enzymatic activity. However, glycosaminoglycan storage, survival, molecular markers (Atg8a, Lamp1, Rab11), and locomotion behavior were not affected. Even strongly reduced, IDS-activity was enough to prevent a pathological phenotype in a MPS II RNAi fruit fly. Thus, a Drosophila MPS II model requires complete abolishment of the enzymatic activity.

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Detection of Ten New Mutations by Screening the Gene Encoding Factor IX of Danish Hemophilia B Patients

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653867 ◽

1995 ◽

Vol 73 (05) ◽

pp. 774-778 ◽

Cited By ~ 7

Author(s):

Marianne Schwartz ◽

Jørgen Ingerslev ◽

Elma Scheibel ◽

Lise Rud Nielsen

Keyword(s):

Point Mutations ◽

Splice Site Mutation ◽

Factor Ix ◽

Hemophilia B ◽

Missense Mutations ◽

Coding Region ◽

Site Mutation ◽

Gene Encoding ◽

Base Pair Deletion ◽

Wide Range

SummaryHemophilia B is caused by a wide range of mutations. In order to characterize the mutations among patients in Denmark, we have systematically screened the entire coding region, the promoter region and exon flanking sequences of the gene encoding factor IX using single strand conformation and heteroduplex analyses. Patients from 32 different families were examined, and point mutations (23 different) were found in all of them. Ten of the mutations have not been reported by others; they include a splice site mutation, a single base pair deletion, and missense mutations. Notably, the study contains a female patient and a previously described Leyden mutation. In ten families with sporadic cases of hemophilia B, all 10 mothers were found to be carriers. The origin of two of these mutations was established.

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Differences in MPS I and MPS II Disease Manifestations

International Journal of Molecular Sciences ◽

10.3390/ijms22157888 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7888

Author(s):

Christiane S. Hampe ◽

Brianna D. Yund ◽

Paul J. Orchard ◽

Troy C. Lund ◽

Jacob Wesley ◽

...

Keyword(s):

Dermatan Sulfate ◽

Treatment Options ◽

Neurological Involvement ◽

Type I ◽

Ionic Balance ◽

Lysosomal Storage ◽

Enzyme Replacement ◽

Mps Ii ◽

Corneal Clouding ◽

Mps I

Mucopolysaccharidosis (MPS) type I and II are two closely related lysosomal storage diseases associated with disrupted glycosaminoglycan catabolism. In MPS II, the first step of degradation of heparan sulfate (HS) and dermatan sulfate (DS) is blocked by a deficiency in the lysosomal enzyme iduronate 2-sulfatase (IDS), while, in MPS I, blockage of the second step is caused by a deficiency in iduronidase (IDUA). The subsequent accumulation of HS and DS causes lysosomal hypertrophy and an increase in the number of lysosomes in cells, and impacts cellular functions, like cell adhesion, endocytosis, intracellular trafficking of different molecules, intracellular ionic balance, and inflammation. Characteristic phenotypical manifestations of both MPS I and II include skeletal disease, reflected in short stature, inguinal and umbilical hernias, hydrocephalus, hearing loss, coarse facial features, protruded abdomen with hepatosplenomegaly, and neurological involvement with varying functional concerns. However, a few manifestations are disease-specific, including corneal clouding in MPS I, epidermal manifestations in MPS II, and differences in the severity and nature of behavioral concerns. These phenotypic differences appear to be related to different ratios between DS and HS, and their sulfation levels. MPS I is characterized by higher DS/HS levels and lower sulfation levels, while HS levels dominate over DS levels in MPS II and sulfation levels are higher. The high presence of DS in the cornea and its involvement in the arrangement of collagen fibrils potentially causes corneal clouding to be prevalent in MPS I, but not in MPS II. The differences in neurological involvement may be due to the increased HS levels in MPS II, because of the involvement of HS in neuronal development. Current treatment options for patients with MPS II are often restricted to enzyme replacement therapy (ERT). While ERT has beneficial effects on respiratory and cardiopulmonary function and extends the lifespan of the patients, it does not significantly affect CNS manifestations, probably because the enzyme cannot pass the blood–brain barrier at sufficient levels. Many experimental therapies, therefore, aim at delivery of IDS to the CNS in an attempt to prevent neurocognitive decline in the patients.

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A Novel Splice Site Variant in FOXN1 in A Patient with Abnormal Newborn Screening for Severe Combined Immunodeficiency and Congenital Lymphopenia

LymphoSign Journal ◽

10.14785/lymphosign-2021-0013 ◽

2021 ◽

Author(s):

Ori Scott ◽

Jenny Garkaby ◽

Jessica Willett-Pachul ◽

Yehonatan Pasternak

Keyword(s):

Splice Site ◽

Severe Combined Immunodeficiency ◽

Splice Site Mutation ◽

Missense Mutations ◽

Combined Immunodeficiency ◽

Site Mutation ◽

Cd8 Cells ◽

Cell Counts ◽

Epithelial Development ◽

Whole Exome

Background: The Forkhead box protein N1 (FOXN1) is a key regulator of thymic epithelial development, and its complete deficiency leads to a nude-severe combined immunodeficiency (SCID) phenotype. More recently, heterozygous mutations in FOXN1 have been linked with a syndrome of congenital lymphopenia and a wide clinical spectrum, with most cases being caused by missense mutations. Aim: To broaden the genotypic and phenotypic spectrum of heterozygous FOXN1 deficiency. Methods: Case report of a patient with FOXN1 haploinsufficiency due to a novel splice-site mutation. Results: Our patient was identified at 3 weeks of life given an abnormal newborn screen (NBS) for SCID, and was found to have congenital lymphopenia preferentially affecting CD8+ T-cells. Her cellular and humoral function were both excellent, and she has remained entirely asymptomatic and thriving for the first 3 years of her life. The patient was found on whole exome sequencing to carry a heterozygous splice-site mutation in the FOXN1 gene, affecting the Forkhead domain. The mutation was also identified in her asymptomatic mother. Conclusion: Heterozygous FOXN1 mutations are an increasingly-recognized cause of congenital lymphopenia. Our experience suggests most patients remain clinically well, with main manifestation including T-lymphopenia, mostly affecting CD8+ cells. Identification of the same variant in an asymptomatic parent suggests age-dependent improvement in T-cell counts and an overall benign course, while provides impetus for diligent conservative management with regular follow-up.

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TET2 Mutations Are Associated with Poor Outcome in Pediatric AML: A Report From the Children's Oncology Group

Blood ◽

10.1182/blood.v118.21.569.569 ◽

2011 ◽

Vol 118 (21) ◽

pp. 569-569

Author(s):

Matthew A. Kutny ◽

Todd A. Alonzo ◽

Robert B. Gerbing ◽

Daniel Geraghty ◽

Alan S. Gamis ◽

...

Keyword(s):

Pediatric Patients ◽

De Novo ◽

Splice Site Mutation ◽

Missense Mutations ◽

Site Mutation ◽

Nonsense Mutations ◽

Free Survival ◽

Significant Difference ◽

De Novo Aml ◽

Pediatric Aml

Abstract Abstract 569FN2 Mutations of the TET2 gene are implicated in abnormal epigenetic regulation in myeloid cancers. Recent studies of adults with AML have suggested that TET2 mutations (TET2/Mut) are associated with an inferior outcome. However, the prognostic role of TET2/Mut in pediatric AML has not been previously described. We sequenced the entire coding region of the TET2 gene in 403 pediatric patients with de novo AML treated on Children's Cancer Group study CCG-2961 (n=169) and Children's Oncology Group study AAML03P1 (n=234). Patients with synonymous mutations and previously reported polymorphisms were considered to be TET2 wild type (TET2/WT). TET2/Mut were identified in 5.2% of patients (25 mutations in 21 patients). Four patients had two distinct mutations: 2 patients had 2 missense mutations, 1 patient had 2 nonsense mutations, and 1 patient had 1 nonsense mutation and 1 splice site mutation. There were 14 different missense mutations, 4 of these each present in 2 patients. There were 5 different nonsense mutations, 1 insertion with frame shift, and 1 splice site mutation. These mutations were scattered throughout the gene from amino acids 171 to 1973. Presence of TET2/Mut was correlated with patient demographics, laboratory characteristics, and clinical outcome. There was no significant difference in gender, median age, presenting WBC count, or FAB classification between patients with or without TET2/Mut. There was a higher percentage of black patients in the TET2/Mut than the TET2/WT group (31.6% vs. 12.6%, P=0.031); there was no significant difference in other racial or ethnic groups. TET2/Mut was not associated with known high risk cytogenetic or molecular markers. There was a higher association of TET2 mutations with favorable risk t(8;21) which was present in 30% of TET2/Mut patients versus 13% of TET2/WT patients (P=0.045). TET2 mutations were not associated with other cytogenetic abnormalities or molecular mutations (FLT3/ITD, CEBPA, NPM1, or WT1 mutations). TET2/Mut and TET2/WT patients had similar clinical remission (CR) rates at the end of induction course 1 (90.5% vs. 80%, P=0.39) and end of induction course 2 (81.0% vs. 79.7%, P=1.00). TET2/Mut patients had an event-free survival (EFS) at 5 years from diagnosis of 29%±20% vs. 45% ±5% for TET2/WT patients (P=0.087). In patients who achieved an initial CR, those with TET2/Mut had a disease-free survival (DFS) at 5 years from remission of 32% ±21% vs. 52% ±6% for TET2/WT patients (P=0.027). Corresponding relapse risk at 5 years from remission was 53% ±23% for TET2/Mut patients vs. 37% ±6% for TET2/WT patients (P=0.10). Due to the association of TET2 mutations with t(8;21), we inquired whether TET2/Mut have prognostic significance within the favorable risk core binding factor (CBF) subgroup of leukemia. Of the 91 patients with CBF leukemia, 9 patients (9.9%) had TET2/Mut. CBF patients with TET2/Mut had lower 5-year EFS (44%±33%) than TET2/WT patients (59%±11%, P=0.084). As CBF patients are considered a low risk group, they do not receive stem cell transplant consolidation in more contemporary clinical protocols. Therefore, we performed clinical outcome evaluation after censoring CBF patients at the time of transplant and found that TET2/Mut patients had an EFS of 39%±35% vs. 57%±12% for TET2/WT patients (P=0.042). In summary, TET2 mutations are present in 5.2% of pediatric patients with de novo AML. Although TET2/Mut are not associated with known high risk markers, patients with these mutations have poor 5-year DFS and show a strong trend toward worse 5-year EFS. TET2/Mut may also be predictive of poor outcome in patients with CBF leukemia. Further evaluation of this molecular abnormality in patients treated on current pediatric cooperative group studies is warranted. Disclosures: No relevant conflicts of interest to declare.

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