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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Homocystinuria with elevated plasma homocysteine and methionine levels is the result of deficient activity of cystathionine synthetase, the enzyme catalyzing conversion of homocysteine to cystathionine. It is inherited as an autosomal recessive trait with a worldwide distribution. The major clinical manifestations result from the elevated plasma homocysteine level. The excitotoxic effect of homocysteic acid accounts for mental retardation and seizures. Interference with collagen cross-linking by sulfhydryl groups of homocysteine causes ectopia lentis and skeletal deformities. Sulfation factor-like effects contribute to disruption of vascular endothelium, which is followed by platelet thrombosis and widespread arterial and venous occlusions. Low methionine homocystinuria, with deficient remethylation of homocysteine, results from deranged vitamin B(12) metabolism and from deficient 5,10-methylene-tetrahydrofolate reductase. Administration of azaribine produces homocystinuria by mechanism not yet elucidated.
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PMID:Homocystinuria: pathogenetic mechanisms. 32 77

Homocystinuria was studied in 27 patients from 15 families in New South Wales. All 2 had biochemical findings consistent with cystathionine synthetase deficiency. One patient was ascertained by newborn screening, but the remaining index cases were detected because of symptoms: poor eyesight 6, mental retardation 3, thromboses 2, skeletal abnormalities 2, and urinary infection1. 9 patients, one-third of all cases, were mildly affected: either they had no features of the disease, or these did not occur until the late teens. Pyridoxine responsiveness was found in 8 sibships, and clinically there were two distinct kinds of response. For patients born in the decade 1960-69 the ascertainment rate for the total population was 1:58 000. The true incidence must be much higher. Our series indicates that homocystinuria occurs more frequently than has heretofore been thought, and that mild cases are common. It is likely that cases are often missed in current newborn screening programmes.
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PMID:Homocystinuria in New South Wales. 64 32

This, to our knowledge, is the first report of homocystinuria in the South African Negro. Two siblings are presented who developed normally until the age of 5 years but then showed mental retardation. Both were tall and thin, had genu valgum and arachnodactyly. The elder sib also had kyphoscoliosis, pes cavus and bilateral ectopia lentis. The diagnosis was confirmed by the presence of homocystine in the urine, elevated plasma homocystine and methionine and diminished plasma cystine levels.
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PMID:Homocystinuria in two South African Negro siblings. 89 68

The case is described of a child, age 6 1/2 years, with retarded mental development, mild neurological signs and abnormal metabolism of sulphur-containing amino acids and methylmalonate, due to an inborn error in the formation of vitamin B12 coenzymes. The patient was treated for almost three years with hydroxycobalamin, folic acid, pyridoxine and choline. Though physical growth was normal, she continued to demonstrate a moderate degree of mental retardation. A brother of the patient died at the age of 5 years, probably of a similar, but undiagnosed, disorder. As far as we are aware there are only four other reported cases similar to the case described here. Two of these patients died and in other other two the defect was so mild that no treatment was necessary and who, in fact, showed appreciable improvement during the follow-up period, which to date amounts to 3 years and 3 months. For reasons detailed in the discussion, it is suggested that the diagnosis of homocystinuria is not complete until studies of folate and vitamin B12 metabolism are undertaken at the same time, so as to identify the metabolic defect(s) responsible for the condition.
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PMID:A unique case of derangement of vitamin B12 metabolism. 102 7

The first case in the dental literature of congenital contractural arachnodactyly (C.C.A. syndrome) is presented. This newly delineated syndrome is an autosomal dominant heritable disorder of connective tissue. Its similarities to Marfan's syndrome and homocystinuria, as well as other syndromes, are discussed. The lack of cardiovascular disease, specific ocular anomalies, and mental retardation are presented in the differential diagnosis of the C.C.A syndrome with Marfan's syndrome and homocystinuria.
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PMID:The C.C.A. syndrome (congenital contractural arachnodactyly): a new differential syndrome for Marfan's syndrome and homocystinuria. 105 23

Governmental officials as well as medical scientists in Taiwan have worked hard in recent years to develop and to implement various measures, such as prenatal diagnosis and neonatal screening, to lower the incidence of hereditary diseases and mental retardation in the population. An inquiry into the possibility of devising a chromosomal and biochemical screening program and to apply it routinely to all the mentally retarded school children island-wide was the major aim of the present study. A collection of 1,614 blood samples was screened for phenylketonuria (PKU), galactosemia, homocystinuria, biotinidase deficiency, and congenital hypothyroidism. The IQ of these children ranged from 50-75 (1,397 children, moderate group) to less than 50 (217 children, severe group). Six cases of PKU (one tetrahydrobiopterin deficient and five classical) and three cases of thyroid dysfunction were found. The overall incidence of these two diseases was 0.56%. Of the 1,614 blood samples, 1,323 were cultured and karyotyped successfully. One hundred and twenty-five of them had chromosome abnormalities. The majority (64 out of 125) were trisomy 21. A remarkable difference in the percentage of mentally retarded children with chromosome abnormalities was observed between the moderate (7.87%) and severe (17.51%) retarded.
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PMID:Chromosomal and biochemical screening on mentally retarded school children in Taiwan. 175 40

Homocystinuria is an inborn error of methionine metabolism, of which cause is mainly deficiency of cystathionine synthetase. The major clinical manifestations of homocystinuria are mental retardation, seizures, ectopia lentis, skeletal deformities and occlusive vascular disease. A case of homocystinuria accompanied with deep cerebral venous thrombosis was reported. A 29-year-old woman was admitted to our hospital with unconsciousness and tetraparesis on December 7, 1984. She was diagnosed as homocystinuria due to cystathionine synthetase deficiency at 13-year-old. Amino acid analysis of serum revealed homocystinaemia (1.37 mg/dl, normal 0), hypermethioninaemia (1.27 mg/dl, normal 0.2-0.48) and low cystathionine content. CT scan revealed intraventricular hemorrhage and diffuse low density in basal ganglia and white matter. Cerebral angiograms showed that deep cerebral veins and superior sagittal sinus can not be recognized clearly in any phase, and Sylvian veins are opacified markedly. It is suggested that intraventricular hemorrhage, and low density area in basal ganglia and white matter is due to hemorrhagic infarction by venous thrombosis of internal cerebral vein. The major clinical manifestations of homocystinuria result from the elevated plasma homocysteine level. The excitotoxic effect of homocysteic acid accounts for mental retardation and seizures.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Homocystinuria accompanied with cerebral deep venous thrombosis--a case report]. 236 35

Classic homocystinuria is an autosomal recessive metabolic disease due to a cystathionine-beta-synthase deficiency with consequent blocking of homocysteine and serine condensation for producing cystathionine. The characteristic biochemical abnormalities in the blood and urine are: abnormal accumulation of methionine, abnormal presence of homocystine and low values of cystathionine, cysteine or cystine (disulfide of the cysteine). The most frequent clinical signs are: subluxation of the lenses, mental retardation of different degrees, long bones excessively lengthened, scoliosis, susceptibility to arterial and venous thromboembolism. The latter is frequent after surgery, and may be life-threatening. This disease must be differentiated from Marfan's syndrome via laboratory tests.
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PMID:Clinical and laboratory features of homocystinuria. 268 Aug 8

Nutritional approaches are available for the management of several different classes of inborn metabolism errors. In phenylketonuria (PKU), phenylalanine is not properly metabolized; and its accumulation leads to neurologic dysfunction and metal retardation. Altering the diet to limit phenylalanine intake led to remarkable improvement in children with PKU. It was later found that instituting dietary therapy immediately after identification of the disorder in newborns prevented mental retardation. Throughout the 1960s nutritional therapies were found for other inborn disorders, including galactosemia, maple syrup urine disease, and homocystinuria. For the group of disorders associated with defects in the urea cycle, leading to profound hyperammonemia, therapy based on the concept of waste nitrogen excretion (i.e., by increasing excretion of urea cycle intermediates in the urine, nitrogen that would otherwise recycle as ammonia can be eliminated) dramatically produced better control of hyperammonemia and its consequences. Some inborn errors of metabolism respond to vitamin therapy. Biotin-related multiple carboxylase synthetase deficiency can be produced by either of two enzyme defects--holocarboxylase synthetase deficiency or biotinidase deficiency. Both are treatable with biotin supplementation. The symptoms of multiple carboxylase deficiency can also occur after intestinal resection or ingestion of raw eggs. Multiple carboxylase deficiency has been treated successfully in utero by giving the mother biotin supplements. Peroxisomal disorders may respond to dietary management. Liver disease in hereditary tyrosinemia may be accentuated by hypermethioninemia and treated by controlling the blood methionine level. Glycogen storage disease Type I, which causes hypoglycemia, can be controlled by oral administration of cornstarch.
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PMID:Nutritional therapy for selected inborn errors of metabolism. 268 28

Five-hundred and fifty one mentally retarded children from seven institutes in Northern Taiwan were screened by dried blood spot for the detection of treatable congenital metabolic diseases, including congenital hypothyroidism, phenylketonuria, homocystinuria, maple syrup urine disease and galactosemia. We found 2 children (0.36%) with congenital hypothyroidism, 1 case (0.18%) of classical phenylketonuria and two cases (0.36%) of trisomy 21 associated with autoimmune thyroiditis. The results of our investigation suggest that congenital hypothyroidism and phenylketonuria can be the factors causing mental retardation among children in Taiwan and mass neonatal screening of these treatable inborn metabolic diseases is strongly indicated for efficiently circumventing mental retardation in our community.
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PMID:Screening of congenital hypothyroidism, phenylketonuria, galactosemia, homocystinuria, and maple syrup urine disease in moderate to severe mentally retarded Chinese children. 278 33


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