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

A fragile site on the X chromosome has been implicated in mental retardation and behavioral problems among both males and females. The fragile-X syndrome is second only to Down syndrome among causes of mental retardation associated with cytogenetic abnormalities. The clinical phenotype is extremely variable. During the early years, many affected children demonstrate normal or near-normal intellect and development. Folic acid may be of benefit before puberty.
 ...
PMID:Fragile-X syndrome. 265 6

Fragile X syndrome, second only to Down syndrome among etiologies of mental retardation, was discussed. Clinical, intellectual, and anthropometric characteristics from 67 fragile X positive males, 35 fragile X positive females, and 27 obligate carriers among 29 families was presented. Regression analysis showed little correlation between level of intellect and frequency of fragile sites. The mean IQ among the various age groups of male patients decreased with increasing age, and some intellectual deterioration could not be ruled out. Folic acid was suggested as a viable treatment mode among prepubescent males.
 ...
PMID:Fragile X syndrome: a common etiology of mental retardation. 356 90

Congenital errors of folate metabolism can be related either to defective transport of folate through various cells or to defective intracellular utilization of folate due to some enzyme deficiencies. Defective transport of folate across the intestine and the blood-brain barrier was reported in the condition 'Congenital Malabsorption of Folate'. This disease is characterized by a severe megaloblastic anaemia of early appearance associated with mental retardation. Anaemia is folate-responsive, but neurological symptoms are only poorly improved because of the inability to maintain adequate levels of folate in the CSF. A familial defect of cellular uptake was described in a family with a high frequency of aplastic anaemia or leukaemia. An isolated defect in folate transport into CSF was identified in a patient suffering from a cerebellar syndrome and pyramidal tract dysfunction. Among enzyme deficiencies, some are well documented, others still putative. Methylenetetrahydrofolate reductase deficiency is the most common. The main clinical findings are neurological signs (mental retardation, seizures, rarely schizophrenic syndromes) or vascular disease, without any haematological abnormality. Low levels of folate in serum, red blood cells and CSF associated with homocystinuria are constant. Methionine synthase deficiency is characterized by a megaloblastic anaemia occurring early in life that is more or less folate-responsive and associated with mental retardation. Glutamate formiminotransferase-cyclodeaminase deficiency is responsible for massive excretion of formiminoglutamic acid but megaloblastic anaemia is not constant. The clinical findings are a more or less severe mental or physical retardation. Dihydrofolate reductase deficiency was reported in three children presenting with a megaloblastic anaemia a few days or weeks after birth, which responded to folinic acid. The possible relationship between congenital disorders such as neural tube defects or dihydropteridine reductase deficiency and disturbances of folate metabolism are discussed. Neurological symptoms present in most of these congenital disorders highlight the role of folate in the central nervous system.
 ...
PMID:Congenital errors of folate metabolism. 853 63

Fragile X syndrome is the leading inherited form of mental retardation, and second only to Down's syndrome as a cause of mental retardation attributable to an identifiable genetic abnormality. Fragile X syndrome is caused by a defect in the fragile X mental retardation 1 gene (FMR1), located near the end of the long arm of the X chromosome. FMR1 normally synthesises the fragile X protein (FMRP), but mutations in FMR1 lead to a lack of FMRP synthesis, resulting in fragile X syndrome. While the specific function of FMRP is not yet fully understood, the protein is known to be important for normal brain development. The physical, cognitive and behavioural features of individuals with fragile X syndrome depend on gender (females have two X chromosomes, one active and one inactive) and the molecular status of the mutation (premutation, full mutation or mosaic). Features of the behavioural profile of individuals with fragile X syndrome include hypersensitivity to stimuli, overarousability, inattention, hyperactivity and (mostly in men) explosive and aggressive behaviour to others or self. Social anxiety, other anxiety disorders, depression, impulse control disorder and mood disorders are the most common psychiatric disorders diagnosed in individuals with fragile X syndrome, although no formal studies have been undertaken. There have been very few psychopharmacological studies of the treatment of behaviours associated with fragile X syndrome. These limited studies and surveys of psychotropic drugs used in individuals with fragile X syndrome suggest that stimulants are helpful for hyperactivity, that alpha(2)-adrenoceptor agonists and beta-adrenoceptor antagonists help to control overarousability, impulsivity and aggressiveness, and that SSRIs can control anxiety, impulsivity and irritability, alleviate depressive symptoms and decrease aggressive and self-injurious behaviour. Typical and atypical antipsychotics in combination with other psychotropics have been used for control of psychotic disorders and severe aggressive behaviours. Mood stabilisers have been found to be useful when mood dysregulation or mood disorders are present with or without aggressive behaviour. Folic acid and L-acetylcarnitine (levacecarnine) have not been found to improve deficits or behaviours. As there is no specific psychotropic drug for any of the deficits or behaviours associated with fragile X syndrome, clinicians are advised to diagnose any psychiatric syndromes or disorders present and treat them with the appropriate psychotropic drug. If no psychiatric disorder can be diagnosed and the patient's challenging behaviours cannot be controlled with environmental manipulation or behaviour modification techniques, the most benign psychotropic drug should be used. Antipsychotics should be reserved for psychotic disorders, for impulse control disorders (used in combination with other psychotropics), or when challenging behaviours constitute an emergency. In the future, new medications targeting molecules implicated in the modulation of anxiety, fear and fear responding will be useful for treating the social anxiety and overarousability exhibited by individuals with fragile X syndrome.
 ...
PMID:Neuropsychiatric symptoms of fragile X syndrome: pathophysiology and pharmacotherapy. 1533 Jun 85

The authors describe a 6-year-old girl with developmental delay, psychomotor regression, seizures, mental retardation, and autistic features associated with low CSF levels of 5-methyltetrahydrofolate, the biologically active form of folates in CSF and blood. Folate and B12 levels were normal in peripheral tissues, suggesting cerebral folate deficiency. Treatment with folinic acid corrected CSF abnormalities and improved motor skills.
 ...
PMID:Cerebral folate deficiency with developmental delay, autism, and response to folinic acid. 1578 39

Micronutrients are essential to sustain life and for optimal physiological function. Widespread global micronutrient deficiencies (MNDs) exist, with pregnant women and their children under 5 years at the highest risk. Iron, iodine, folate, vitamin A, and zinc deficiencies are the most widespread MNDs, and all these MNDs are common contributors to poor growth, intellectual impairments, perinatal complications, and increased risk of morbidity and mortality. Iron deficiency is the most common MND worldwide and leads to microcytic anemia, decreased capacity for work, as well as impaired immune and endocrine function. Iodine deficiency disorder is also widespread and results in goiter, mental retardation, or reduced cognitive function. Adequate zinc is necessary for optimal immune function, and deficiency is associated with an increased incidence of diarrhea and acute respiratory infections, major causes of death in those <5 years of age. Folic acid taken in early pregnancy can prevent neural tube defects. Folate is essential for DNA synthesis and repair, and deficiency results in macrocytic anemia. Vitamin A deficiency is the leading cause of blindness worldwide and also impairs immune function and cell differentiation. Single MNDs rarely occur alone; often, multiple MNDs coexist. The long-term consequences of MNDs are not only seen at the individual level but also have deleterious impacts on the economic development and human capital at the country level. Perhaps of greatest concern is the cycle of MNDs that persists over generations and the intergenerational consequences of MNDs that we are only beginning to understand. Prevention of MNDs is critical and traditionally has been accomplished through supplementation, fortification, and food-based approaches including diversification. It is widely accepted that intervention in the first 1,000 days is critical to break the cycle of malnutrition; however, a coordinated, sustainable commitment to scaling up nutrition at the global level is still needed. Understanding the epidemiology of MNDs is critical to understand what intervention strategies will work best under different conditions.
 ...
PMID:The epidemiology of global micronutrient deficiencies. 2604 25

Chromosome fragile sites tend to form gap or break in chromosomes when the cells are exposed to replication stress. Folic acid deprivation in the culture medium induces folate-sensitive rare fragile sites, such as FRAXA which is responsible for the fragile X mental retardation syndrome. Chromosome instability at fragile sites can be evaluated by biomarkers of genomic instability such as frequency of micronuclei (MN). It was aimed to analyse the chromosome content of MN in Fragile X cells during folate deprivation by the MN-fluorescence in situ hybridization (FISH) method. Samples from five Fragile X syndrome patients, diagnosed using cytogenetic and molecular methods, as well as from their parents and five controls were included in the study. Blood samples were cultured in two different culture media (folate-deficient and normal). Results of MN-FISH test were analysed in terms of MN frequency and chromosome content of MN. An accumulation of MN in Fragile X patients, mainly containing T (+) or C (+) MN or T (+) plus C (+) MN in binucleated cells was found. Finally, MN-FISH analysis allowed confirming that the increase in MN frequency is due to a higher sensitivity to chromosome breakage along the X chromosome.
 ...
PMID:Analysis of Xq27.3 Fragility Using the Micronucleus-Fluorescence In situ Hybridization Assay. 3311 Apr 86