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)

Two brothers showed severe and persistent hyperchloraemic metabolic acidosis (capillary blood pH 7.07--7.15) due to a low renal bicarbonate threshold at 11 mmol/l. The maximal tubular capacity for bicarbonate reabsorption was reduced to about half the normal. A high dose of acetazolamide (25 mg/kg) lowered the tubular bicarbonate reabsorption substantially, indicating the presence of carbonic anhydrase. Both the glomerular filtration rate, the renal blood flow and the renal concentrating capacity were slightly reduced. The clinical characteristics were: growth retardation, mental retardation, nystagmus, corneal opacities, cataract, glaucoma and enamel defects of the permanent teeth. Serum thyroxine was pathological low without clinical signs of hypothyreosis. The erythrocytes showed an increased osmotic resistance. Autopsy of the younger brother, who died 4 1/2 years old, revealed thyroid and thymus weights of 25% of the normal. The kidney tubular cells were swollen with vacuoles. The glomeruli had a normal appearance.
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PMID:Congenital persistent proximal type renal tubular acidosis in two brothers. 4 68

X-linked DMD is a serious condition characterized by progressive muscle wasting and weakness and death ensues in the late teens or early twenties. There is considerable clinical variability even within families and some suggestions of genetic heterogeneity. Though skeletal muscle is primarily involved, other tissues are also affected including cardiac and smooth muscle. Other abnormalities include mental retardation, thymus hyperplasia and possibly certain endocrinological changes. The responsible locus is at Xp21 and the gene product is a very large protein (dystrophin) which is normally localised to muscle cell membranes. It is hypothesised that its absence in DMD may result in instability of the muscle cell membrane with resultant ingress of calcium, an increase in intracellular calcium, and cell death. An understanding of this pathway is important in devising an effective treatment.
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PMID:Clinical and molecular studies in Duchenne muscular dystrophy. 266 10

Rhizomelic chondrodysplasia punctata (RCDP) is a sublethal autosomal recessive disorder characterized by skeletal dysplasia, microcephaly, mental retardation, congenital cataracts, joint contractures, skin changes, and failure to thrive. Prenatal ultrasound diagnosis has been reported during the second trimester of pregnancy. Prenatal diagnosis is also possible from the first trimester onwards by demonstration of peroxisomal dysfunction in cultured chorionic villous or amniotic fluid cells. In all cases reported hitherto, the prenatal diagnosis was established after the birth of a previous affected child. In contrast to these studies in pregnant multiparous women at risk for RCDP, we report on the first case of prenatal ultrasound diagnosis of RCDP at 19 weeks' gestation in a primigravida. In addition, a complex cardiac malformation associated with hypoplasia of the thymus (DiGeorge anomaly) is described.
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PMID:Prenatal ultrasound diagnosis of rhizomelic chondrodysplasia punctata in a primigravida. 799 19

DiGeorge syndrome (DGS) is predominantly caused by partial monosomy 22q11, but a subset of patients with DGS show deletions of 10p or other chromosomal abnormalities. The authors describe a 20 months old girl with DGS and a monosomy 10p bringing the number of DGS patients with this chromosomal abnormality to nine. She has a monosomy 10p13-pter and a trisomy 10q26-qter due to a meiotic recombination of a maternal inversion (10) (p13q26). The proposita's phenotype demonstrates typical features of the del (10p) syndrome which include mental retardation, abnormally shaped skull, hypertelorism, low nasal bridge, micrognathia, dysmorphic low set ears, short neck, foot abnormalities, and cardiac defect. The diagnosis of DGS was made unequivocally within the first weeks of life because of the typical features-cardiac defect, hypoplastic thymus, T-cell defect, hypocalcemia, and hypoparathyroidism. The common DGS mutation-microdeletion 22q11-was excluded by FISH analysis, and the breakpoints on chromosome 10 were mapped between D10S189 and D10S191 on the short arm and proximal to D10S25 on the long arm.
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PMID:DiGeorge syndrome and partial monosomy 10p: case report and review. 854 Jun 88

The human Cu/Zn superoxide dismutase (hSOD-1) gene, catalyses the dismutation of O2 to H2O2 and O2. It is located on chromosome 21 in q22.1 and is overexpressed in Down's syndrome (DS) patients. These patients present various abnormalities including mental retardation, congenital heart disease, immunological deficits and premature aging. In order to explore the potential role of SOD-1 overexpression in DS, we have generated two lineages of transgenic mice for the hSOD-1 gene and studied, at the ultrastructural level, the effect of hSOD-1 overexpression on the thymic microenvironment. Modification of the cellular architecture and morphology associated with a lipidic invasion, signs of a premature involution of the thymus, were observed in both lineages. A rupture of the filamentous network in the extracellular and probably also in the intracellular matrix was first observed. These results correlate the thymic alterations visualized in light microscopy, on the thymus from DS patients, and raise the question of the relationship between the SOD-1 overexpression and the different morphological alterations associated with the premature thymic involution observed in SOD-1 transgenic mice. They suggest that thymic and immunological impairments present in DS patients may be related to the SOD-1 gene dosage effect.
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PMID:Premature thymic involution, observed at the ultrastructural level, in two lineages of human-SOD-1 transgenic mice. 922 11

Down syndrome (DS) is associated with mental retardation, immune disorders and congenital heart diseases. Although it is usually caused by the presence of an extra chromosome 21, a subset of the diagnostic phenotypic features may be caused by the presence of the band 21q22, called the "Down syndrome region". Many proteins important for the immune and nervous systems as CuZn-superoxide dismutase (SOD-1), CD18-beta chain of LFA-1, interferon receptor, APP-amyloid precursor protein, protein S-100 beta are coded by chromosome 21. Overexpression of these molecules may contribute to the thymic derangement that results in anomalous maturation leading to functionally impaired T cells. Many factors have been shown to contribute to the immune deficiency which results in high susceptibility to infections, high rate of malignancies, and autoimmune phenomena in persons with DS. The main disorders in the immune system include thymus abnormalities, changes in cell-mediated immunity, phagocytosis, antibodies-mediated immunity and a high prevalence of autoantibodies in persons with DS. Furthermore, the duplication of chromosome 21 genes may generate most of the pathological changes in the central nervous system. There is an increased prevalence of seizure disorders. Such widespread alterations in the cortical areas seem to account for specific impairments observed in short-term and long-term memory, language skills, and cognitive and learning processes. If all principles of optimal health care and adequate education were followed without exception for persons with DS, then the quality of their life could be improved significantly and they would be able to become productive citizens in the society. (Tab. 5, Fig. 3, Ref. 42.)
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PMID:[Down's syndrome--effect of increased gene expression in chromosome 21 on the function of the immune and nervous system]. 926 31

To investigate molecular and clinical aspects of conotruncal anomaly face (CAF), we studied the correlation between deletion size and phenotype and the mode of inheritance in 183 conotruncal anomaly face syndrome (CAFS) patients. Hemizygosity for a region of 22ql1.2 was found in 180 (98%) of the patients with CAFS by fluorescence in situ hybridization (FISH) using the N25(D22S75) DiGeorge critical region (DGCR) probe. No hemizygosity was found in three (2%) of the patients with CAFS by FISH using nine DiGeorge critical region probes and a SD1OP1 probe (DGA II locus). None of these three patients had mental retardation and just one had nasal intonation, which was observed in almost all of the 180 CAFS patients who carried deletions (mental retardation, 92%; nasal voice, 88%). Nineteen of 143 families (13%) had familial CAFS and 16 affected parents (84%) were mothers. Although only two of the affected parents had cardiovascular anomalies, the deletion size in the 16 affected parents and their affected family members, who were studied by FISH analysis, was the same. It indicates that extragenic factors may play a role in the genesis of phenotypic variability, especially in patients with cardiovascular anomalies. No familial cases were found among CAFS patients with absent thymus/DiGeorge anomaly (DGA). Also, in all 18 CAFS patients with completely absent thymus/DGA and all 6 CAFS patients with schizophrenia, it was revealed that the deletion was longer distally. A study of the origin of the deletion using microsatellite analyses in 48 de novo patients showed that in 65% of CAFS patients it was maternal, while in 64% of DGA patients it was paternal. The findings of this study indicated that CAF was almost always associated with the deletion of 22ql1.2. As well as the major features of the syndrome, other notable extracardiac anomalies were found to be susceptibility to infection, schizophrenia, atrophy or dysmorphism of the brain, thrombocytopenia, short stature, facial palsy, anal atresia, and mild limb abnormalities.
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PMID:Molecular and clinical study of 183 patients with conotruncal anomaly face syndrome. 973 80

Duchenne muscular dystrophy (DMD) is caused by a defect in a 427-kDa membrane-associated protein: dystrophin. The DMD gene also encodes several shorter isoforms which are believed to participate in nonmuscle manifestations of DMD, including abnormal retinal electrophysiology, dilated cardiomyopathy, mental retardation, and hearing defects. The purpose of this work was to determine the normal tissue expression of full-length dystrophin (Dp427) and the dystrophin isoforms Dp260, Dp140, Dp116, and Dp71, to aid in understanding what roles these isoforms might play in DMD nonmuscle manifestations. RT-PCR was performed on mRNA isolated from wild-type C57BL/6J mouse tissues, including brain, cardiac muscle, eye, intestine, kidney, liver, lung, skeletal muscle, spleen, stomach, testis, thymus, and uterus. RT-PCR amplification demonstrated that the isoforms were in a number of tissues which had not been revealed by previous Western and Northern blot analyses. Dp427 was expressed at equal levels in all tissues. Dp260 and Dp140 were present in all tissues tested, but the levels of expression varied. Dp116 was expressed in a subset of tissues and levels of expression varied. Dp71 was constitutively expressed in all tissues, suggesting that this isoform plays a basic role in normal tissue function. The expanded tissue distribution supports the hypothesis that dystrophin isoforms serve essential and unique functions, necessitating further investigation into their potential roles in DMD nonmuscle manifestations.
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PMID:Redefinition of dystrophin isoform distribution in mouse tissue by RT-PCR implies role in nonmuscle manifestations of duchenne muscular dystrophy. 988 14

FMR2 is the gene associated with FRAXE fragile site non-specific mental retardation (FRAXE MRX). Previously a male patient was identified with developmental delay and speech problems who had a deletion within intron 3 of FMR2. No known FMR2 exonic sequences were missing in this patient. Detailed northern blot analysis revealed existence of a new large isoform of FRM2 in foetal brain. This isoform was characterised and found to be due entirely to an addition of an extra 4.9 kb of the 3' UTR to the previously characterised 8.755 kb FMR2 transcript. This excluded involvement of the large FMR2 isoform in the MRX phenotype of three individuals now known to have the same deletion of intron 3 FMR2 sequences. Expression studies on the new 13.7 kb FMR2 isoform show that it is expressed predominantly in foetal brain and adult pituitary gland, whilst the expression of the shorter previously characterised 8.755 kb isoform is broader, including testis, thymus and placenta. Possible consequences of the alternative processing and expression of FMR2 for the molecular pathology of FRAXE MRX are discussed.
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PMID:Characterisation and expression of a large, 13.7 kb FMR2 isoform. 1019 98

Patients with a deletion of chromosome band 22q11 are described as having DiGeorges syndrome, velocardiofacial syndrome or chromosome 22q11 deletion syndrome depending on clinical manifestations. The patients have variable severity and combinations of conotruncal heart defects, abnormalities of the ear and palate, facial dysmorphism and mental retardation as well as partial or complete aplasia/hypoplasia of the thymus and endocrine dysfunction, e.g. hypoparathyroidism. The patients may present with impaired immune function, heart failure, hypocalcaemia, facial dysmorphism, impaired hearing and mental retardation. The syndrome, which is a significant cause of heart and craniofacial defects as well as mental retardation, is probably underdiagnosed. In each of the above mentioned phenotypical presentations, chromosome 22q11 deletion syndrome should be considered.
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PMID:[DiGeorge syndrome. Velocardiofacial syndrome/chromosome 22q11 deletion syndrome]. 1082 40


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