Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mucolipidosis II is a severe inherited lysosomal storage disease characterized by profound psychomotor retardation, severe Hurler-like skeletal changes and normal urinary mucopolysaccharide excretion. Mucolipidosis II is a related disorder distinguished by its milder course, milder to absent mental retardation and survival to adult life. Cultivated fibroblasts from patients with both of these disorders display large inclusions on phase microscopy and reduced levels of many acid hydrolases. However, culture medium fibroblasts out the body fluids of affected patients show enormously elevated levels of these hydrolases. The lysosomal enzyme activities in serum, leukocytes, fibroblasts extracts and culture medium from seven patients with mucolipidosis II are similar to those found in four cases of mucolipidosis III. The findings of excessive excretion of sialyl-oligosaccharide in urine and of increased level of sialic acid compounds in cultured fibroblasts associated with a sialidase deficiency in leukocytes, fibroblasts and serum are discussed.
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PMID:[Mucolipidosis. biologic characteristics (author's transl)]. 11 47

Three atypical patients with clinical and laboratory findings of Hurler syndrome, but without alpha-L-iduronidase deficiency, are described. Clinical features included characteristic facies, mental retardation, corneal clouding, dysostosis multiplex, restriction of joint mobility, and hepatosplenomegaly. Excessive amounts of chondroitin sulfate B and heparitin sulfate were excreted in the urine. alpha-L-Iduronidase activities in leucocytes and liver tissues were within the normal range or somewhat elevated.
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PMID:Atypical Hurler syndrome without alpha-L-iduronidase deficiency. 13 68

The most common inborn error of glycoprotein catabolism appears to be aspartylglycosaminuria (AGU). It is characterized by deepening mental retardation, progressive lesions of connective tissue, and increased urinary excretion of aspartyglycosylamine. The first symptoms usually appear after 3 years of age and closely resemble those of Hurler's disease. The condition is a hereditary lysosomal storage disease due to a defective enzyme. The main clinical findings in a infantile type of neuronal ceroid-lipofuscinosis (INCL) are psychomotor retardation, visual failure, and a virtually isoelectric E.E.G. at the final stage of the disease. The symptoms of this hereditary disorder first appear between 8 and 18 months of age and the mean age at death is 6.5 years. Striking cerebral and cerebellar atrophy, together with neuronal loss and accumulation of lipofuscin-like material, can be observed at neuropathological examination.
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PMID:Recent findings on some "new" neurometabolic diseases. 103 35

beta-Mannosidase deficiency was demonstrated in fibroblasts of a girl who showed severe psychomotor retardation, bone deformities and gargoylism and recurrent skin and respiratory infections and who died at 20 years of age from bronchopneumonia. This first demonstration of a female patient confirms the autosomal recessive inheritance of beta-mannosidosis. Further investigation of this gypsy family revealed beta-mannosidosis in an older brother with a milder manifestation of gargoyl facial dysmorphology, mental retardation, hearing impairment and recurrent infections. beta-Mannosidase activity was completely deficient in his cultured skin fibroblasts, leukocytes and plasma. In urine a characteristic disaccharide was present. Heterozygote levels of beta-mannosidase were found in fibroblasts and/or plasma of the parents and one sister.
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PMID:Beta-mannosidase deficiency: heterogeneous manifestation in the first female patient and her brother. 207 35

Mucopolysaccharidosis type I (i.e., Hurler, Hurler-Scheie, and Scheie syndromes) and type II (i.e., Hunter syndrome) are lysosomal storage disorders resulting from alpha-L-iduronidase (IDUA) deficiency and iduronate-2-sulfatase (IDS) deficiency, respectively. The a priori probability that both disorders would occur in a single individual is approximately 1 in 5 billion. Nevertheless, such a proband was referred for whom clinical findings (i.e., a male with characteristic facies, dysostosis multiplex, and mental retardation) and biochemical tests indicated these concomitant diagnoses. In repeated studies, leukocyte 4 methylumbelliferyl-alpha-L-iduronidase activities in this kindred were as follows: <1.0 nmol/mg protein/h in the proband and proband's clinically normal sister; 45.3 in mother; and 45.7 in father (normal range 65.0-140). Leukocyte L-O-(alpha-iduronate-2-sulfate)-(1->4)-D-O-2,5-anhydro[1-3H]mannitol-6- sulfate activities were as follows: 0.0 U/mg protein/h in the proband; 5.7 in his sister; 4.9 in mother; and 15.0 in father (normal range 11.0-18.4). Multiple techniques, including automated sequencing of the entire IDS and IDUA coding regions, were employed to unravel the molecular genetic basis of these intriguing observations. The common IDS mutation R468W was identified in the proband, his mother, and his sister, thus explaining their biochemical phenotypes. Additionally, the proband, his sister, and his father were found to be heterozygous for a common IDUA mutation, W402X. Notably, a new IDUA mutation A300T was also identified in the proband, his sister, and his mother, accounting for reduced IDUA activity in these individuals; the asymptomatic sister, whose cells demonstrated normal glycosaminoglycan metabolism, is thus a compound heterozygote for W402X and the new allele. This A300T mutation is the first IDUA pseudodeficiency gene to be elucidated at the molecular level.
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PMID:Molecular genetic defect underlying alpha-L-iduronidase pseudodeficiency. 855 71

This is believed to be the first report on estimating hearing loss in Hurler's disease, based on the correlation between ABR and temporal bone pathology. ABR findings revealed hearing loss to be about 70 dB or more as result of peripheral mixed impairment. A histological study of the temporal bones revealed almost all pathological findings in the conductive system, except for the hyperplastic arachnoid in the internal auditory canal. In the middle ear cavity, otitis media, residual mesenchyme and deformity of ossicles were found. We explain the conductive component to be due to otitis media and poor ossicular connection. However, the etiology of the sensorineural component remains speculative. In Hurler's disease, hearing loss with mental retardation is often found at infantile age. Therefore, assessing the extent of hearing loss exactly was difficult, for example, the severity. the etiology and incidence of sensorineural impairment. We emphasize the need for not only well-described pathological studies but also for more objective functional investigations, at least ABR.
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PMID:ABR and temporal bone pathology in Hurler's disease. 957 28

Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the hydrolysis of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation and hepatosplenomegaly (sialidosis type II). We have analyzed the genomic DNA from nine sialidosis patients of multiple ethnic origin in order to find mutations responsible for the enzyme deficiency. The activity of the identified variants was studied by transgenic expression. One patient had a frameshift mutation (G623delG deletion), which introduced a stop codon, truncating 113 amino acids. All others had missense mutations: G679G-->A (Gly227Arg), C893C-->T (Ala298Val), G203G-->T (Gly68Val), A544A-->G (Ser182Gly) C808C-->T (Leu270Phe) and G982G-->A (Gly328Ser). We have modeled the three-dimensional structure of sialidase based on the atomic coordinates of the homologous bacterial sialidases, located the positions of mutations and estimated their potential effect. This analysis showed that five mutations are clustered in one region on the surface of the sialidase molecule. These mutations dramatically reduce the enzyme activity and cause a rapid intralysosomal degradation of the expressed protein. We hypothesize that this region may be involved in the interface of sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in their high-molecular-weight complex required for the expression of sialidase activity in the lysosome.
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PMID:Characterization of the sialidase molecular defects in sialidosis patients suggests the structural organization of the lysosomal multienzyme complex. 1076 32

Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the catabolism of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots, and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation, and hepatosplenomegaly (sialidosis type II). We analyzed the effect of the missense mutations G68V, S182G, G227R, F260Y, L270F, A298V, G328S, and L363P, which are identified in the sialidosis type I and sialidosis type II patients, on the activity, stability, and intracellular distribution of sialidase. We found that three mutations, F260Y, L270F, and A298V, which are clustered in the same region on the surface of the sialidase molecule, dramatically reduced the enzyme activity and caused a rapid intralysosomal degradation of the expressed protein. We suggested that this region might be involved in sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in the multienzyme lysosomal complex required for the expression of sialidase activity. Transgenic expression of mutants followed by density gradient centrifugation of cellular extracts confirmed this hypothesis and showed that sialidase deficiency in some sialidosis patients results from disruption of the lysosomal multienzyme complex.
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PMID:Mutations in sialidosis impair sialidase binding to the lysosomal multienzyme complex. 1127 74

The lysosomal storage disorder, mucopolysaccharidosis type I (MPS I), is caused by a deficiency of the enzyme alpha-L-iduronidase, which is involved in the breakdown of dermatan and heparan sulphates. There are three clinical phenotypes, ranging from the Hurler form characterised by skeletal abnormalities, hepatosplenomegaly and severe mental retardation, to the milder Scheie phenotype where there is aortic valve disease, corneal clouding, limited skeletal problems, but no mental retardation. In this study, 85 MPS I families (73 Hurler, 5 Hurler/Scheie, 7 Scheie) were screened for 9 known mutations (Q70X, A75T, 474-2a>g, L218P, A327P, W402X, P533R, R89Q, 678-7g>a). W402X was the most frequent mutation in our population (45.3%) and Q70X was the second most frequent (15.9%). In 30 families, either one or both of the mutations were not identified, which accounted for 25.9% of the total alleles. Therefore, all 14 exons of the alpha-L-iduronidase gene were screened in these patients and 23 different sequence changes were found, 17 of which were previously unknown. The novel sequence changes include 4 deletions (153delC, 628del5, 740delC, 747delG), 5 nonsense mutations (Q60X, Y167X, Q400X, R619X, R628X), 6 missense mutations (C205Y, G208V, H240R, A319V, P496R, S633L), a splice site mutation (IVS12+5g>a), and a rare polymorphism (A591T). The polymorphism and novel missense mutations were transiently expressed in COS-7 cells and all of them except the polymorphism showed complete loss of enzyme activity. In total, 165 of the 170 mutant alleles were identified in this study and despite the high frequency of W402X and Q70X, the identification of many novel mutations unique to individual families further highlights the genetic heterogeneity of MPS I.
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PMID:Mutational analysis of 85 mucopolysaccharidosis type I families: frequency of known mutations, identification of 17 novel mutations and in vitro expression of missense mutations. 1173 25

Hurler syndrome (HS) is an autosomal recessive, inherited metabolic storage disorder due to deficiency of lysosomal alpha-L-iduronidase (IDU) enzyme activity. Untreated patients develop progressive mental retardation and multisystem morbidity with a median life expectancy of 5 years. Allogeneic hematopoietic cell transplantation (HCT) can achieve stabilization and even improvement of intellect, with long-term survival. However, children with HS have an increased incidence of graft failure, usually with concomitant autologous marrow reconstitution. Between 1983 and 2000, 71 Hurler children underwent HCT at the University of Minnesota. Of these 71, 19 (27%) experienced graft failure. We report HCT outcomes in all 11 Hurler patients receiving a second HCT at the University of Minnesota. Median age at second HCT was 25 months (range, 16 to 45 months); median time from first HCT was 8 months (range, 4 to 18.5 months). The conditioning regimen consisted of cyclophosphamide/TBI/ATG (n = 8) or busulfan/cyclophosphamide/ATG (n = 3). The source of bone marrow was an unrelated donor in six, matched sibling in four, and mismatched related in one. Five of the 11 grafts were T cell depleted prior to infusion. Overall, 10 of 11 patients showed donor-derived engraftment, of whom three developed grade 3 to 4 acute GVHD. Five of 11 patients are surviving a median of 25 months (range, 2 months to 12 years) with an overall actuarial survival of 50% (95% CI, 27% to 93%) at 4 years. All five show sustained donor engraftment with normalization of IDU activity levels. Three of five evaluable patients demonstrated stabilization of neuropsychological function after second HCT. Currently, allogeneic donor-derived hematopoiesis provides the only chance for long-term survival and improved quality of life in Hurler patients. While graft failure in Hurler patients requires further investigation, a timely second HCT can be well-tolerated and beneficial.
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PMID:Outcome of second hematopoietic cell transplantation in Hurler syndrome. 1196 Feb 68


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