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)

A male patient with mental retardation and typical clinical features of 10p trisomy syndrome was found to have a duplication of the short arm of chromosome 10 attached to the short arm of the Y chromosome. Quantitative evaluation of nine red cell enzymes showed significantly increased activity levels of HK1 and, to a lesser extent, of PK, PGI, 6PGD, and G6PD. It is suggested that the HK1 locus may be in the 10pter leads to p12 region. The increased levels of HK1 could affect other erythrocyte metabolic pathways slowing down the physiological rate of cellular senescence and result in increased activity levels of other cell-age-dependent enzymes.
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PMID:Increased HK1 activity levels in the red cells of a patient with a de novo trisomy 10p: t(Y;10)(p11;p12). 46 60

A combined preventive scheme was conducted in four hospitals in Guangzhou to lower the rate of kernicterus and mental retardation caused by related neonatal jaundice due to G6PD deficiency. Observation was focused on 330 G6PD deficient infants, and the effects were measured according to the incidence of hyperbilirubinemia and kernicterus. The results, as compared to those of a retrospective study, showed that the incidence of hyperbilirubinemia was significantly decreased (51.4% to 21.2%), and neither kernicterus nor mental retardation infant was found in this series (12.5% in the control group). The authors conclude that this combined scheme is extremely effective and can be used in any large population area in which there is a high gene frequency of G6PD deficiency.
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PMID:[Clinical study on the prevention of kernicterus caused by hereditary glucose-6-phosphate dehydrogenase deficiency]. 133 14

The still debated question of whether the expression of mental retardation in heterozygous carriers of the Martin-Bell syndrome is influenced by X inactivation has been investigated in a group of phase-known double heterozygotes for the FRA-X mutant and the G6PD Mediterranean variant. In these individuals, the number of somatic cells (fibroblasts or red cells) with an active FRA-X chromosome could be assessed through the G6PD phenotype at the single-cell level. The data reported indicate a significant inverse correlation between the IQ level (as measured by the Wechsler-Bellevue test) and the percentage of fibroblast cells with an FRA-X active chromosome. In contrast, no significant correlation was found when the IQ level and red cell data were compared, thus suggesting the occurrence of somatic selection against hematopoietic stem cells with an active FRA-X chromosome.
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PMID:Mental retardation in heterozygotes for the fragile-X mutation: evidence in favor of an X inactivation-dependent effect. 231 20

One of the commonest forms of X-linked mental retardation is associated with a fragile site at Xq27 on the human X chromosome which can be visualised structurally after culturing cells in folate-deficient media. Unusually, the mutation can be transmitted through a phenotypically normal male. There is already some evidence that the gene loci for G6PD and factor IX are linked to this mental retardation locus. We have followed the inheritance of a DNA sequence 52A, in fragile site families that are also informative for factor IX. We demonstrate that these probes are localised at Xq27/Xq28-Xqter, close physically to the fragile site. We did not find close linkage between 52A, factor IX, and the fragile site in the families studied despite 52A and factor IX showing linkage in normal families. We discuss the importance of these data for the genetic mapping of this region of the human X chromosome and the implication for the use of these DNA probes for clinical diagnosis.
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PMID:Linkage studies of X-linked mental retardation: high frequency of recombination in the telomeric region of the human X chromosome (fragile site/linkage/recombination/X chromosome). 299 Nov 15

The q26-q28 region of the human X chromosome contains several important disease loci, including the locus for the fragile X mental retardation syndrome. We have characterized new polymorphic DNA markers useful for the genetic mapping of this region. They include a new Bell restriction fragment length polymorphism (RFLP) detected by the probe St14-1 (DXS52) and which may therefore be of diagnostic use in hemophilia A families. A linkage analysis was performed in fragile X families and in large normal families from the Centre d'Etude du Polymorphisme Humain (CEPH) by using seven polymorphic loci located in Xq26-q28. This multipoint linkage study allowed us to establish the order centromere-DXS100-DXS86-DXS144-DXS51-F9-FRAX+ ++-(DXS52-DXS15). Together with other studies, our results define a cluster of nine loci that are located in Xq26-q27 and map within a 10 to 15 centimorgan region. This contrasts with the paucity of markers (other than the fragile X locus) between the F9 gene in q27 and the G6PD cluster in q28, which are separated by about 30% recombination.
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PMID:Multipoint genetic mapping of the Xq26-q28 region in families with fragile X mental retardation and in normal families reveals tight linkage of markers in q26-q27. 350 1

Eighteen Sardinian pedigrees segregating for the X-fragile site syndrome were studied with respect to the segregation of the fragile site (FS) at Xq28, mental retardation, and macro-orchidism. No exception was found in the association of this symptomatic triad (MOM-X) in 41 out of 42 patients examined. The exceptional individual had micro- rather than macro-orchidism and was found to have a 47, XXY sex chromosome complement. In six informative sibships, the MOM-X syndrome was found to segregate in close linkage association with G6PD-deficiency or protan colorblindness. The maximum likelihood estimate of recombination if 6% with 90% fiducial limits between 2.5 and 19.5% and an odds ratio in favor of measurable linkage of 428:1. However, no hint of measurable linkage was found in six pedigrees segregating for G6PD and the Renpenning syndrome or other unspecified types of X-linked mental retardation. These data give strong support to the generally held hypothesis that the FS at Zq28, characteristic of the MOM-X syndrome, is a direct expression of a genetic change in the same chromosomal region. They also clearly suggest that X-linked MR without FS may be the result of different allelic mutations at the same locus.
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PMID:Brief report: linkage between G6PD and fragile-X syndrome. 660 50

FG syndrome is an X-linked condition comprising mental retardation, congenital hypotonia, macrocephaly, distinctive facial changes, and constipation or anal malformations. In a linkage analysis, we mapped a major FG syndrome locus [FGS1] to Xq13, between loci DXS135 and DXS1066. The same data, however, clearly demonstrated genetic heterogeneity. Recently, we studied a French family in which an inversion [inv(X)(q12q28)] segregates with clinical symptoms of FG syndrome. This suggests that one of the breakpoints corresponds to a second FG syndrome locus [FGS2]. We report the results of fluorescence in situ hybridization analysis performed in this family using YACs and cosmids encompassing the Xq11q12 and Xq28 regions. Two YACs, one positive for the DXS1 locus at Xq11.2 and one positive for the color vision pigment genes and G6PD loci at Xq28, were found to cross the breakpoints, respectively. We postulate that a gene might be disrupted by one of the breakpoints.
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PMID:Mapping of X chromosome inversion breakpoints [inv(X)(q11q28)] associated with FG syndrome: a second FG locus [FGS2]? 1107 72

Congenital methemoglobinemia is a relatively rare clinical disorder characterized by life-long cyanosis, caused by either an inherited mutant hemoglobin (Hb-M) or deficiency of physiologically active NADH-dependent methemoglobin reductase (NADH-MR). NADH-MR deficiency leads to two different types of recessive congenital methemoglobinemia. In type I, cyanosis is the only major symptom and NADH-MR deficiency is restricted only to the red blood cells. In type II, cyanosis is associated with severe mental retardation and neurological impairment. The objective of this study is to establish the cause of cyanosis in our cases of congenital methaemoglobinemia. Erythrocyte NADH-MR activity was assayed spectrophotometrically. Spectral analysis of the hemolysate treated with potassium ferricyanide was recorded between 400-700 nm and Hb electrophoresis on starch gel at pH 7.0 was done to rule out the presence of Hb-M. NADH-MR deficiency was detected in 3 families. There was a history of consanguinity in one of these cases. The three propositi presented with breathlessness, fever and peripheral cyanosis. There was no history of cardiac illness or exposure to drugs and chemicals. There were no signs and symptoms of mental retardation. The presence of Hb-M was ruled out. Hb-A2, Hb-F, G6PD activity and reduced glutathione levels were normal. NADH-MR activity in all the cases ranged from 4.1 to 9.2 IU/g Hb (normal range 7.0-24.0 IU/g Hb). We describe NADH-MR deficiency in three unrelated cases (age 4 months to 6 years) where the activity of the enzyme was 30-40% of normal. These three cases of congenital methemoglobinemia are due to type-I NADH-MR deficiency without mental retardation.
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PMID:Congenital methemoglobinemia due to NADH-methemoglobin reductase deficiency in three Indian families. 1280 31