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)

There are differences between young and adult organisms regarding toxokinetic aspects and clinical manifestations of heavy metal intoxications. Chronically, toxic Cd intake causes a microcytotic hypochromic anemia in young rats at lower exposure levels and after shorter exposure periods than in adult animals. Cd absorption is increased by co-administration of milk and in conjunction with iron deficiency. After long exposure periods toxic Cd concentrations accumulate in the kidney cortex; this process starts very early in life. In 3-year-old children Cd concentrations in the kidney can reach up to one-third of those found in adults. Hg++ and methyl-Hg can cause Hg encephalopathia, and frequently cause mental retardation in adults. Correspondingly, Hg++ accumulation in the brains of suckling rats is approx. 10 times higher than in grown animals. Milk increases the bioavailability of Hg++. In suckling rats Hg is bound to a greater extent to ligands in the erythrocytes. Methyl-Hg concentrations in breast milk reach 5% of those in maternal plasma and that is a severe hazard for breastfed children of exposed mothers. Toxic Pb concentrations can lead to Pb encephalopathia. A high percentage of surviving children have seizures and show signs of mental retardation. Anemia and reduced intelligence scores were recently observed in children after exposure to very low levels of Pb. Pb absorption is increased in children and after co-administration of milk. There are no definite proofs for carcinogenesis or mutagenesis after oral exposure to Cd, Hg, and Pb in man. Heavy metal concentrations were found in the same order of magnitude in commercial infant formulas and in breast milk. When infant formulas are reconstituted with contaminated tap water, however, Pb and Cd concentrations can be much higher. The average heavy metal uptake from such diets exceeds the provisional tolerable weekly intake levels set by the WHO for adults, calculated on the basis of an average food intake and a downscaled body weight. These considerations do not even provide for differences in absorption and distribution or for the increased sensitivity of children to heavy metal exposure. However, dilution effects for essential heavy metals were observed in fast-growing young children; this effect might be extrapolated to toxic metals. These theoretical considerations are compared with epidemiological evidence. A health statistic from Baltimore shows a decline of Pb intoxications in infants. This observation correlates with a simultaneous decline in exposure to Pb which was due, for example, to decreased use of lead dyes in house paints and the abolition of tin cans for infant food.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[The toxicological estimation of the heavy metal content (Cd, Hg, Pb) in food for infants and small children]. 218

We describe a child with ATR-16 [alpha-thalassemia (thal)/mental retardation], who was referred for genetic evaluation because of minor anomalies and developmental delay. Cytogenetic analysis demonstrated a de novo complex rearrangement of chromosome 16. Fluorescence in situ hybridization (FISH) analysis, using chromosome 16 subtelomeric probes, showed that this patient had a deletion of the distal short arm of chromosome 16 that contains the alpha-globin genes and a duplication of 16q. Analysis of the alpha-globin locus by Southern blot showed a half normal dose of the alpha-globin gene. Microsatellite marker studies revealed that the duplicated 16q region was maternal in origin. Hematological studies revealed anemia, hypochromia and occasional cells with Hb H inclusion bodies. A hematological screening for alpha-thal should be considered in patients with mild developmental delay and a suggestive phenotype of ATR-16 with microcytic hypochromic anemia and normal iron status. The stellate pattern of the iris, a new finding in our patient, may contribute to a better clinical delineation of both syndromes, ATR-16 and/or duplication of 16qter.
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PMID:ATR-16 due to a de novo complex rearrangement of chromosome 16. 1592 Nov 66

Alpha thalassemia retardation associated with chromosome16 (ATR-16 syndrome) is defined as a contiguous gene syndrome resulting from haploinsufficiency of the alpha-globin gene cluster and genes involved in mental retardation (MR). To date, only few cases have been described which result from pure monosomy for a deletion of 16p. In most of these cases the deletion was identified by densitometric analysis of Southern blot results or by Fluorescent In Situ Hybridization analysis, and these alterations have not been mapped in detail. In this study, we have fine mapped deletions causing alpha-thalassemia within 2 Mb from the telomere of 16p by multiplex ligation-dependent probe amplification (MLPA). We have developed a rapid and simple test for high resolution mapping of rearrangements involving the tip of the short arm of chromosome 16 by incorporating 62 MLPA probes spaced approximately 10-200 kb over a region of 2 Mb from the telomere. One deletion of approximately 900 kb without MR was identified in addition to three de novo deletions varying between 1.5 and 2 Mb causing ATR-16 in three patients having mild MR and alpha-thalassemia. Two were found by chance to be ATR-16 because they were included in a study to search for telomeric loss in MR and not by hematological analysis. This would plead for more alertness when a persistent microcytic hypochromic anemia at normal ferritin levels is observed as suggestive for the ATR-16 syndrome. The region on chromosome 16p for which haploinsufficiency leads to the dysmorphic features and MR typical for ATR-16, has been narrowed down to a 800 kb region localized between 0.9 and 1.7 Mb from the telomere.
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PMID:Refinement of the genetic cause of ATR-16. 1759 30