Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00492 (hypoxanthine-guanine phosphoribosyltransferase)
 2,385 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hyperuricaemia in Down's syndrome is unreleated to the activity of phosphoribosylamidotransfrease, which catalyses the activity of the first specific step on the purine biosynthetic pathway, and to the activity of hypoxanthine phosphoribosyltransferase and phosphoribosylpyrophosphate synthetase, abnormalities of which are known to be associated with hyperuricaemia. Immunological studies involving serum immunoglobulins, natural E. coli antibodies, test immunization with pneumococcal polysaccharide type III (PnPS), in vitro lymphocyte transformation to mitogens, and pokeweed mitogen (PWM) induced immunoglobulin production showed no difference between hyperuricaemic or normouricaemic Down's patients and institutionalized controls. The Down's patients had higher serum IgA, IgG and IgE, and some also produced more immunoglobulin in PWM-stimulated lymphocyte cultures when compared to normal healthy controls. However, both patients with Down's syndrome and the institutionalized controls had significantly lower responses to PnPs than normal healthy controls. The only deficiency confined to the Down's patients was a signficant depression in delayed hypersensitivity to dinitrochlorobenzene. These findings indicate that the in vivo abnormality of depressed cellular and humoral immunity in Down's patients is not paralleled by in vitro function as measured by PHA lymphocyte transformation and immunoglobulin production by PWM-stimulated lymphocytes. There is also no apparent link between a putative defect in purine metabolism in Down's patients and any immunological abnormalities.
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PMID:Immunological and purine enzyme studies on hyperuricaemic and normouricaemic patients with Down's syndrome. 15 48

In the search for homologous chromosome regions in man and mouse, the locus for cytoplasmic superoxide dismutase (SOD-1; superoxide:superoxide oxidoreductase, EC 1.15.1.1) is of particular interest. In man, the SOD-1 gene occupies the same subregion of chromosome 21 that causes Down syndrome when present in triplicate. Although not obviously implicated in the pathogenesis, SOD-1 is considered to be a biochemical marker for this aneuploid condition. Using a set of 29 mouse-Chinese hamster somatic cell hybrids, we assign Sod-1 to mouse chromosome 16. Isoelectric focusing permits distinction between mouse and Chinese hamster isozymes, and trypsin/Giemsa banding distinguishes mouse from Chinese hamster chromosomes. The mouse fibroblasts used were derived from a male mouse carrying Searle's T(X;16)16H reciprocal translocation in which chromosomes X and 16 have exchanged parts. Analysis of informative hybrids leads to regional assignment of Sod-1 to the distal half of mouse chromosome 16 (16B4 --> ter). Because the Chinese hamster cell line (380) used for cell hybridization is deficient in hypoxanthine phosphoribosyltransferase (HPRT; IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8), that part of the mouse X chromosome carrying the complementing Hprt gene can be identified by selection in hypoxanthine/aminopterin/thymidine medium and counterselection in 8-azaguanine. Mouse Hprt is on the X(T) translocation product containing the proximal region X cen --> XD.
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PMID:Assignment of the gene for cytoplasmic superoxide dismutase (Sod-1) to a region of chromosome 16 and of Hprt to a region of the X chromosome in the mouse. 29 39

Aneuploidy (abnormal chromosome number) is the principal hereditary abnormality associated with either parental age or tendencies to originate in 1 parent more often than the other. Risk increases logarithmically with advancing parental age; at age 40, the risk is about 2%. In Down's syndrome, maternal age is a primary factor, but occasionally the father can be implicated. Maternal age is slightly more important than paternal age for other aneuploid syndromes. The anomalies of translocation, inversion, or deletion occur as commonly in males as females and are independent of age. They are an important factor in counseling because of their frequency and because clinically normal individuals can be carriers of genetically balanced anomalies. The risk for producing abnormal offspring can exceed 30%. A history of either several spontaneous abortions or offspring with multiple anomalies is an indication for chromosome analyses on both parents. Among known gene disorders, the severity of X-linked disorders differs in males and females. Gene mutations originate more frequently among males, and the frequency increases with advancing paternal age, particularly implicated are the Marfan syndrome, achondroplasia, hemophilia A, and the Lesch-Nyhan syndrome.
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PMID:Congenital deformities and chromosomal disorders: maternal versus paternal age. 88 78

Neonates with Down's syndrome occasionally show an excess of blasts in their peripheral blood. This disorder spontaneously resolves within several months and is called transient abnormal myelopoiesis (TAM) or transient myeloproliferative disorder. It has been uncertain whether the excess of blasts in TAM is a result of a clonal proliferation or a polyclonal reactive condition. The clonality of cells in females can be examined by analysis of the methylation patterns of the X chromosomes of proliferating cells using restriction fragment length polymorphism (RFLP). Using this strategy, we studied three females with Down's syndrome accompanied by TAM who showed heterozygosity in RFLP of either the hypoxanthine phosphoribosyltransferase or phosphoglycerate kinase gene. Analysis of the methylation patterns of these genes demonstrated a clonal nature for blasts in three patients. Thus, TAM is a clonal proliferative disorder. In addition, lymphocytes with a normal appearance contained in analyzed samples from these patients also showed a monoclonal pattern, suggesting that TAM may be a disorder of multipotent stem cells.
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PMID:Monoclonal nature of transient abnormal myelopoiesis in Down's syndrome. 167 97

The activities of a number of purine metabolizing enzymes of erythrocytes and lymphocytes were determined in 18 subjects with Down's syndrome and in 18 age- and sex-matched control subjects. An increase of adenosine deaminase activity (adenosine or deoxyadenosine as substrates) was found in erythrocytes (P less than 0.001) as well as in lymphocytes (P less than 0.001) of Down's syndrome subjects compared to controls. The purine nucleoside phosphorylase activities in lymphocytes and plasma urate concentrations were also significantly higher in Down's syndrome subjects than in controls (P less than 0.001 and less than 0.02, respectively). Adenine phosphoribosyltransferase activities and hypoxanthine-guanine phosphoribosyltransferase activities in lymphocytes were identical in the two groups. In all subjects studied there were positive correlations between the erythrocyte adenosine deaminase activities, lymphocyte adenosine deaminase or deoxyadenosine activities, and plasma urate concentrations (P less than 0.05 in all cases), and between lymphocyte nucleoside phosphorylase and lymphocyte adenosine deaminase or deoxyadenosine deaminase activities (P less than 0.01 and less than 0.05, respectively). The results suggest that increased activities of some purine metabolizing enzymes found in both erythrocytes and lymphocytes may contribute to increased purine degradation and hyperuricemia in subjects with Down's syndrome. In addition, the increased adenosine deaminase and nucleoside phosphorylase activities may be related to the immunological dysfunction found in subjects with Down's syndrome.
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PMID:Levels of some purine metabolizing enzymes in lymphocytes from patients with Down's syndrome. 294 6

At this time a rather large number of congenital abnormalities still occur. About 2-3% of pregnancies will result in children with major congenital abnormalities that cannot be detected prenatally. Yet, with the availability of prenatal diagnosis for an ever increasing number of genetic problems and, more recently, for developmental problems as well, a new option was offered to couples at risk when they took the risk of pregnancy: finding out whether the fetus was abnormal. An early argument regarding the ethics of this option was formulated by Dan Callahan, director of the Hastings Institute for Ethics, Society and the Life Sciences, when he indicated the need to be careful about the term "option." A need exists to be careful about societal pressures in favor of the new medical options--on, for example, a pregnant woman who is over 35 and does not get a prenatal diagnosis; or on a woman carrying a Down's syndrome child identified by prenatal diagnosis not to have an abortion. This was the 1st specter raised when prenatal diagnosis was introduced. The most common indication for amniocentesis is the risk of chromosomal abnormalities. The risk of discovering a chromosomal abnormality by amniocentesis is about double the risk at birth because a number of chromosomally abnormal fetuses are lost late in the 2nd trimester by spontaneous abortion. The age cutoff at 35 raises an immediate ethical question: since the total number of births to women over age 35 seems to be increasing, and at the same time a greater and greater percentage of children with Down's syndrome are born to women under age 35, the question arises as to whether amniocentesis should be done on all pregnancies, and whether all births with Down's syndrome should be selectively aborted or avoided. Amniocentesis in all pregnancies is impractical at this time from the technological and the cost perspective, but the ethical question should be raised. Among the X-linked disorders, 1 group cannot be specifically diagnosed in utero by prenatal diagnosis. If a woman is known to be a carrier, her daughters won't have the disease, but half of them will be carriers. Regarding sex preference as a reason for amniocentesis, all the geneticist can and should do is provide a couple with a base of knowledge and understanding of the options available to them and the outcome of each option. X-linked disorders such as hemophilia and Lesch-Nyhan syndrome and the autosomal recessive biochemical disorders or inborn errors of metabolism such as Tay-Sachs disease and over 100 others can now be diagnosed prenatally. In the vast majority of cases, amniocentesis is performed because the parents already have an abnormal child. Screening programs for Tay-Sachs disease, for sickle cell anemia, and for thalassemia also detect couples at risk. A variety of tools other than amniocentesis are now available for prenatal diagnosis. Much work is being conducted in the prenatal diagnosis of sickle cell anemia and thalassemia.
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PMID:Genetics, amniocentesis, and abortion. 660 72

Recombinant DNA techniques provide new approaches to the diagnosis and analysis of inherited human diseases associated with mental retardation. Examples of such diseases include the Lesch-Nyhan syndrome, phenylketonuria, the Fragile X syndrome, Down syndrome, and those associated with deletions or duplications of subchromosomal regions, e.g., the proximal short arm of human chromosome #15. For a limited but increasing number of diseases, the DNA sequences responsible for the phenotype (e.g., sequences coding for abnormal proteins) can be isolated directly. In many other cases, DNA segments mapping near genes responsible for diseases of interest can be isolated, e.g., from recombinant phage libraries enriched for specific regions of the genome by metaphase chromosome flow-sorting and then used in molecular linkage studies to "track" the abnormal gene in a pedigree. Both the necessary technology and the methods for its application continue to improve, and the impact of recombinant DNA studies in the field of mental retardation should increase markedly in the very near future.
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PMID:Molecular genetic approaches to human diseases involving mental retardation. 673 92

Tissue culture of immortal cell strains from diseased patients is an invaluable resource for medical research but is largely limited to tumor cell lines or transformed derivatives of native tissues. Here we describe the generation of induced pluripotent stem (iPS) cells from patients with a variety of genetic diseases with either Mendelian or complex inheritance; these diseases include adenosine deaminase deficiency-related severe combined immunodeficiency (ADA-SCID), Shwachman-Bodian-Diamond syndrome (SBDS), Gaucher disease (GD) type III, Duchenne (DMD) and Becker muscular dystrophy (BMD), Parkinson disease (PD), Huntington disease (HD), juvenile-onset, type 1 diabetes mellitus (JDM), Down syndrome (DS)/trisomy 21, and the carrier state of Lesch-Nyhan syndrome. Such disease-specific stem cells offer an unprecedented opportunity to recapitulate both normal and pathologic human tissue formation in vitro, thereby enabling disease investigation and drug development.
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PMID:Disease-specific induced pluripotent stem cells. 1869 44

Syndrome-specific behavior was proposed by Langdon Down in his first clinical descriptions. Research interest followed but waned during the eugenics era when antisocial behavior was attributed to people with intellectual disability (ID) and the US Supreme Court legalized involuntary sterilization. When these claims were refuted and behavioral treatments introduced, their focus on environmental determination minimized the importance of biological research. The modern era began with the recognition that patterned behavior, for example, self-injury in Lesch-Nyhan syndrome and hyperphagia in PWS, was syndrome-specific, and when parent support groups pointed out syndrome-specific behavioral similarities in their children. Syndrome-specific rating scales and methodologies followed to allow behavioral comparisons between syndromes. The focus initially was on specific behaviors but with refinements in neuropsychological tests has expanded to include neurocognitive profiles. Greater clarification in genetic diagnoses has led to mutant mouse behavioral models and neurophysiologic and neuroimaging strategies have made possible the study of brain circuits. There is growing interest in investigating the developmental trajectory of behaviors from infancy to adulthood and old age. Because anxiety, mood disturbance, repetitive behaviors, and social deficits commonly occur in people with severe ID, those affected are often given multiple psychiatric diagnoses. This has led to considerable confusion in the literature. It is critical to focus on specific behaviors and cognitive patterns in research and not confuse psychiatric symptoms that lack precise definitions and involve multiple genes, the so-called psychiatric phenotype, with the more specific behavioral phenotype. New treatments based on knowledge of underlying neurobiology call for more fine-grained definition of behavior.
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PMID:Advances in understanding behavioral phenotypes in neurogenetic syndromes. 2098 68