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- Hietala, M, et al.
(författare)
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DNA-based carrier screening in primary healthcare : screening for aspartylglucosaminuria mutations in maternity health offices
- 1996
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Ingår i: Clinical Chemistry. - 0009-9147 .- 1530-8561. ; 42:9, s. 1398-1404
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale genetic screening programs are complex enterprises in which ethical, technical, medical, and socioeconomic aspects have to be handled with professional expertise. Establishment of automated, relatively robust, and inexpensive laboratory techniques is one step of this path. Here a pilot carrier-screening program for the mutations causing aspartylglucosaminuria was carried out for pregnant women in primary care maternity health offices. Women (1975) were tested before their 12th week of pregnancy, and 31 heterozygotes were detected. The sampling was based on dried blood strips, facilitating convenient handling and inexpensive mailing to the laboratory. The mutation detection technique, solid-phase mini-sequencing simplified by the use of scintillation microplates and automated equipment, proved to be rapid, simple, inexpensive, and reliable, with a low repeat rate (2.5%). In conclusion, we found that good collaboration between the primary healthcare unit, the laboratory, and counseling experts, combined with modern laboratory technology, facilitate reliable low-cost genetic testing.
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| 5. |
- Hietala, M, et al.
(författare)
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Prospects of carrier screening of aspartylglucosaminuria in Finland
- 1993
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Ingår i: European Journal of Human Genetics. - 1018-4813 .- 1476-5438. ; 1:4, s. 296-300
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Tidskriftsartikel (refereegranskat)abstract
- The frequency of carriers of the AGUFin mutation, the predominant mutation causing aspartylglucosaminuria in Finland, was determined in a population sample comprising 553 newborns from a delivery hospital in southern Finland, and 607 from a hospital in northern Finland. The AGUFin point mutation was identified from cord blood samples using the PCR-based, solid-phase minisequencing method. Nineteen carriers of the AGUFin mutation were detected, 8 (1:69) in the sample from the southern and 11 (1:55) from the northern population, respectively. The solid-phase minisequencing method proved to be rapid and convenient for the detection of the AGUFin mutation, and can readily be applied in large-scale carrier screening at the population level.
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| 6. |
- Ikonen, E, et al.
(författare)
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Aspartylglucosaminuria : cDNA encoding human aspartylglucosaminidase and the missense mutation causing the disease
- 1991
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Ingår i: EMBO Journal. - 0261-4189 .- 1460-2075. ; 10:1, s. 51-58
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Tidskriftsartikel (refereegranskat)abstract
- We have isolated a 2.1 kb cDNA which encodes human aspartylglucosaminidase (AGA, E.C. 3.5.1.26). The activity of this lysosomal enzyme is deficient in aspartylglucosaminuria (AGU), a recessively inherited lysosomal accumulation disease resulting in severe mental retardation. The polypeptide chain deduced from the AGA cDNA consists of 346 amino acids, has two potential N-glycosylation sites and 11 cysteine residues. Transient expression of this cDNA in COS-1 cells resulted in increased expression of immunoprecipitable AGA protein. Direct sequencing of amplified AGA cDNA from an AGU patient revealed a G----C transition resulting in the substitution of cysteine 163 with serine. This mutation was subsequently found in all the 20 analyzed Finnish AGU patients, in the heterozygous form in all 53 carriers and in none of 67 control individuals, suggesting that it represents the major AGU causing mutation enriched in this isolated population. Since the mutation produces a change in the predicted flexibility of the AGA polypeptide chain and removes an intramolecular S-S bridge, it most probably explains the deficient enzyme activity found in cells and tissues of AGU patients.
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| 7. |
- Ikonen, E, et al.
(författare)
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Dissection of the molecular pathology of aspartylglucosaminuria provides the basis for DNA diagnostics and future therapeutic interventions
- 1993
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Ingår i: Scandinavian journal of clinical and laboratory investigation. Supplementum. - 0085-591X. ; 213, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- Aspartylglucosaminuria (AGU) is exceptional among lysosomal storage diseases since it represents the only known amidase deficiency in man, being caused by an inadequate function of aspartylglucosaminidase (AGA, E.C. 3.5.1.26.). This amidase is essential in one of the final steps in the ordered breakdown of glycoproteins since it cleaves Asn from the residual N-acetylglucosamines (for reviews see 1, 2). The deficiency of the enzyme activity results in the typical lysosomal accumulation of the abnormal degradation products (mainly aspartylglucosamine, 2-acetamido-1-beta-L-aspartamido-1,2-dideoxyglucose) in patients' cells and tissues. The diagnosis of AGU has so far been based on the detection of abnormal metabolites in urine and decreased enzyme activity in the cultured fibroblasts or isolated lymphocytes. Prenatal diagnosis has been possible by demonstrating the deficient enzyme activity of amniocytes or chorion villus biopsies. Identification of carriers has been difficult and unreliable due to the high individual variation in AGA activity and prerequisite for isolated blood lymphocytes. During the past few years we have purified the human enzyme into homogeneity, isolated the full length cDNA and characterized the majority of AGU mutations in this cDNA. This work facilitated the development of a reliable DNA diagnostic test suitable also for large scale carrier screening. The molecular pathology of the most common AGU mutation was unravelled, this being a prerequisite for the oncoming developments for therapy. Although AGU is a relatively rare disease, characterization of the AGU mutations and their cellular consequences have revealed highly interesting new phenomena in the biosynthesis of this lysosomal enzyme, some of which carry general biological significance.
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| 8. |
- Ikonen, E, et al.
(författare)
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Quantitative determination of rare mRNA species by PCR and solid-phase minisequencing
- 1992
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Ingår i: PCR methods and applications. - : Cold Spring Harbor Laboratory. - 1054-9803. ; 1:4, s. 234-240
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Tidskriftsartikel (refereegranskat)abstract
- We present a new method for quantification of mRNA, in which the limitations of the current quantitative PCR methods can be overcome. A known amount of a synthetic RNA standard differing from the mRNA to be quantified by a single nucleotide is reverse-transcribed and amplified together with the mRNA template using a biotinylated primer. The biotinylated PCR product is immobilized on a streptavidin-coated solid support and denatured. The ratio between the two amplified sequences is determined by separate "mini-sequencing" reactions, in which a detection step primer annealing immediately adjacent to the site of the variable nucleotide is elongated by a single labeled dNTP complementary to the nucleotide at the variable site. The ratio between the incorporated labels accurately determines the ratio between the two sequences in the original RNA sample. We applied this method to quantify the mRNA of human aspartylglucosaminidase (AGA) in tissues and cultured cells. AGA is a lysosomal enzyme participating in the degradation of glycoproteins. A mutation in the AGA gene abolishes the enzyme activity and leads to aspartylglucosaminuria (AGU), a recessively inherited metabolic disorder. The mRNA quantification revealed that the normal and mutant genes are expressed at similar levels in kidney, liver, and cultured fibroblast, whereas the amount of AGA mRNA in normal placenta and brain is significantly higher than that found in the corresponding samples from AGU patients. The method presented here is generally applicable for PCR-based quantification of rare mRNAs and DNA as well.
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| 9. |
- Ikonen, E, et al.
(författare)
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Spectrum of mutations in aspartylglucosaminuria
- 1991
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 88:24, s. 11222-11226
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Tidskriftsartikel (refereegranskat)abstract
- Aspartylglucosaminuria (AGU) is an inherited lysosomal storage disorder caused by the deficiency of aspartylglucosaminidase. We have earlier reported a single missense mutation (Cys163----Ser) to be responsible for 98% of the AGU alleles in the isolated Finnish population, which contains about 90% of the reported AGU patients. Here we describe the spectrum of 10 AGU mutations found in unrelated patients of non-Finnish origin. Since 11 out of 12 AGU patients were homozygotes, consanguinity has to be a common denominator in most AGU families. The mutations were distributed over the entire coding region of the aspartylglucosaminidase cDNA, except in the carboxyl-terminal 17-kDa subunit in which they were clustered within a 46-amino acid region. Based on the character of the mutations, most of them are prone to affect the folding and stability and not to directly affect the active site of the aspartylglucosaminidase enzyme.
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| 10. |
- Karttunen, L, et al.
(författare)
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An accurate method for comparing transcript levels of two alleles or highly homologous genes : application to fibrillin transcripts in Marfan patients' fibroblasts
- 1996
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 6:5, s. 392-403
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Tidskriftsartikel (refereegranskat)abstract
- We introduce here a novel and generally applicable, solid-phase minisequencing-based approach for rapid estimation of relative levels of transcripts with high sequence homology. This study was undertaken to screen for the consequences of different fibrillin-1 mutations on the transcript levels in patients with the Marfan syndrome (MFS). This dominantly inherited, connective tissue disorder is characterized by pleiotrophic symptoms in cardiovascular, skeletal, and ocular systems. A spectrum of disease mutations in the gene encoding fibrillin-1 (FBN1), a glycoprotein component of extracellular matrix microfibrils, has been identified in MFS patients, but the mechanisms by which mutations result in different phenotypic manifestations are still unknown to a large extent. Our data from the quantitation of FBN1 transcripts provide support for the hypothesis that mutations causing premature stop codons result in a milder phenotype than classical MFS by reducing the stability of the mutant transcript and, consequently, decreasing the interference of mutant polypeptide in the formation of fibrillin fibers. We also applied this mRNA quantitation method to determine the relative ratio between transcripts from the genes coding for two highly homologous microfibrillar components, FBN1 and FBN2, in control fibroblast cultures as well as in fibroblasts from MFS patients. Interestingly, these data show large variations between the levels of the two transcripts in fibroblast cultures, but these variations do not correlate either with the nature of the disease mutation or to the clinical MFS phenotype.
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