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)

Institutionalized patients with Down syndrome and matched controls with other causes of mental retardation were tested by immune adherence hemagglutination for the presence of antibody to hepatitis A antigen (anti-HA). Altogether 75.1% (175 of 233) exhibited presence of anti-HA, with no differences by sex or age. Patients reactive for hepatitis B surface antigen (HBsAg) or its antibody (anti-HBs) were reactive for anti-HA significantly more frequently than those with a negative reaction for these markers. In contrast to serologic markers of hepatitis type B, prevalence of anti-HA does not depend on the cause of mental retardation or on the age at primary infection. The rate of anti-HA positivity was found to be closely correlated with duration of institutionalization. The study confirmed that many closed institutions for the mentally retarded are hyperendemic for hepatitis type A and that formation of anti-HA is not greatly affected by either immune deficiency or immune immaturity.
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PMID:Antibody to hepatitis A antigen in institutionalized mentally retarded patients. 13 79

Photosensitive genodermatoses associated with established defects of DNA repair currently include the autosomal recessive diseases xeroderma pigmentosum (XP), Cockayne's syndrome (CS), trichothiodystrophy (TTD), and Bloom's syndrome (BS). XP is a heterogeneous disorder associated with defective excision repair or daughter strand repair of ultraviolet (UV)-induced DNA damage. It is characterized by cutaneous and ocular abnormalities predominantly on sun-exposed sites and in some cases, neurological features resulting from progressive neuronal loss. Skin involvement includes easy sunburning, pigmentary abnormalities, telangiectasia, dryness, scarring, and susceptibility to multiple benign and malignant neoplasms. In CS, defective repair of actively transcribing DNA is clinically associated with acute photosensitivity, growth retardation, demyelinating neurological abnormalities, and pigmentary retinal degeneration, but without increased cancer susceptibility. TTD is characterized by sulphur-deficient brittle hair, variable growth delay, mental retardation, ichthyosis, and in some cases photosensitivity. Although in some patients there is a deficiency of DNA excision repair identical to that in certain xeroderma pigmentosum patients, no increased cancer risk is present in trichothiodystrophy. In BS, deficient cellular DNA ligase is associated with congenital telangiectasia, photosensitivity, growth retardation, immune deficiency, increased susceptibility to infection, and predominantly internal rather than cutaneous malignancy. Immunological factors may at least determine the varying susceptibility to malignancy of these conditions.
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PMID:DNA repair deficient photodermatoses. 220 44

We describe two sibs with prenatal-onset growth deficiency, microcephaly, cataracts, mental retardation, enamel hypoplasia, immune deficiency, and generalized delay of ossification. The combination appears to constitute a previously undescribed autosomal recessive syndrome.
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PMID:An apparently new syndrome of microcephalic primordial dwarfism and cataracts. 379 11

a-Mannosidosis (MIM 248500) is an autosomal recessive lysosomal storage disorder resulting from deficient activity of lysosomal alpha-mannosidase (LAMAN) (EC 3.2.1.24). The disease is characterized by massive intracellular accumulation of mannose-rich oligosaccharides with resulting mental retardation, hearing loss, immune deficiency and skeletal changes. We report here the purification and characterization of human placenta LAMAN. The enzyme is synthesized as a single-chain precursor which is processed into three glycopeptides of 70, 42 and 15 kDa. The 70 kDa peptide is further partially proteolysed into three more peptides that are joined by disulfide bridges. The laman cDNA sequence was assembled from overlapping fragments obtained by PCR on human fibroblast and human lung cDNA. The deduced amino acid sequence contains a putative signal peptide of 48 amino acids followed by a polypeptide sequence of 962 amino acids. Northern blot analyses revealed a single transcript of approximately 3.5 kb present in all tissues examined but at varying levels. Two affected siblings of Palestinian origin were homozygous for a mutation that causes a His-->Leu replacement at a position which is conserved among class 2 alpha-mannosidases from several species.
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PMID:alpha-Mannosidosis: functional cloning of the lysosomal alpha-mannosidase cDNA and identification of a mutation in two affected siblings. 915 46

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

Preimplantation genetic diagnosis was performed in 61 day 3 embryos obtained by in-vitro fertilization from seven patient carriers of haemophilia, Marfan's syndrome, Bloch-Sulzemberg syndrome (incontinentia pigmentosa) or X chromosome-linked immune deficiency, retinitis pigmentosa, and FG syndrome, which is characterized by mental retardation and hypotonia. After multiplex polymerase chain reaction, 16 embryos were diagnosed as being unaffected, and these were transferred to the uterus on the following day (day 4). Of these embryos, six (37.5%) implanted, resulting in the delivery of a singleton and a twin pregnancy, a late second trimester miscarriage (twins at week 20) and a first trimester miscarriage at week 8. All the diagnoses were confirmed by amniocentesis. We report for the first time a late day 4 transfer of biopsied human embryos undergoing preimplantation genetic diagnosis. This transfer schedule allows an extra day to perform genetic analyses on single blastomeres and to monitor any adverse effect of the biopsy procedure.
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PMID:Successful outcome with day 4 embryo transfer after preimplantation diagnosis for genetically transmitted diseases. 968 8

During the last 5 years, we diagnosed in Leuven 130 patients with a 22q11 deletion. The deletion was familial in 14 out of 110 index patients (12%), which is significantly less compared to previous studies. In 10 patients, the deletion was maternal, in 4 patients paternal. A cardiac defect was the main presenting symptom in 49% of patients. The other patients were ascertained through developmental delay (16%), behavioural disturbances (7%), otorhinolaryngological manifestations (6%), psychiatric manifestations (3%) and mental retardation (2%). In one patient hypocalcemia was the presenting symptom. In another patient the severe immune deficiency led to diagnosis. Most patients presented a wide variety of the classical features of the Velo-Cardio-Facial syndrome. Velopharyngeal incompetence, learning difficulties or mostly mild mental retardation were almost always present, whereas clinical significant hypocalcemia or immune disturbances were rare. Previously un(der)recognised features include polyhydramnios, renal malformations and laryngotracheamalacia or laryngeal stenosis.
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PMID:Presenting symptoms and clinical features in 130 patients with the velo-cardio-facial syndrome. The Leuven experience. 1019 24

We describe a 3-year-old girl with partial trisomy 4p and partial monosomy 8p who had prenatal and postnatal growth retardation, mental retardation, no speech development, mild synophrys, hirsutism, apparently low-set ears, dysphonic hoarse voice, hyperactivity, and small hands with proximal placement of the thumbs. She had recurrent lung infections, due to earlier aspiration and immune deficiency (chronic granulomatous disease). Cytogenetic findings in this and other cases with suggestive phenotype may point to an additional locus for Brachmann-de Lange phenotype.
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PMID:Three-year-old girl with partial trisomy 4p and partial monosomy 8p with resemblance to Brachmann-de Lange syndrome--another locus for Brachmann-de Lange syndrome on 4p? 1118 1

DNA methylation is not just for basic scientists any more. There is a growing awareness in the medical field that having the correct pattern of genomic methylation is essential for healthy cells and organs. If methylation patterns are not properly established or maintained, disorders as diverse as mental retardation, immune deficiency, and sporadic or inherited cancers may follow. Through inappropriate silencing of growth regulating genes and simultaneous destabilisation of whole chromosomes, methylation defects help create a chaotic state from which cancer cells evolve. Methylation defects are present in cells before the onset of obvious malignancy and therefore cannot be explained simply as a consequence of a deregulated cancer cell. Researchers are now able to detect with exquisite sensitivity the cells harbouring methylation defects, sometimes months or years before the time when cancer is clinically detectable. Furthermore, aberrant methylation of specific genes has been directly linked with the tumour response to chemotherapy and patient survival. Advances in our ability to observe the methylation status of the entire cancer cell genome have led us to the unmistakable conclusion that methylation abnormalities are far more prevalent than expected. This methylomics approach permits the integration of an ever growing repertoire of methylation defects with the genetic alterations catalogued from tumours over the past two decades. Here we discuss the current knowledge of DNA methylation in normal cells and disease states, and how this relates directly to our current understanding of the mechanisms by which tumours arise.
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PMID:Methylation matters. 1133 64

Hoyeraal-Hreidarsson syndrome represents a severe variant of dyskeratosis congenita (Zinsser-Cole-Engman syndrome). This X-linked recessive, progressive, multisystemic disorder reported so far in 12 pedigrees is characterised by intrauterine growth retardation, microcephaly, cerebellar hypoplasia, mental retardation, progressive combined immune deficiency and aplastic anaemia. Mutations in the DKC1gene on Xq28 have been identified in the X-linked form of dyskeratosis congenita and in some Hoyeraal-Hreidarsson syndrome patients. We report on two sibs and two other unrelated patients with the striking clinical features of Hoyeraal-Hreidarsson syndrome. Noticeably, all four had early digestive problems, with chronic, bloody diarrhoea and feeding problems causing one of the most difficult problems in the supportive treatment of this uniformly lethal condition. Pathological changes in the proliferative compartment of the digestive mucosa included alterations of the glandular architecture and focal rarefaction of the glands. This aspect seems consistent with altered telomerase function associated with a dyskerin mutation which may decrease the proliferative capacity of digestive epithelial cells. A missense mutation 146 C-->T (Thr49Met) in the DKC1gene was found in two unrelated patients, whereas mutation screening was negative for one single case. The absence of mutations of the DKC1gene in patients with Hoyeraal-Hreidarsson syndrome emphasises the probable implication of one or more other loci.
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PMID:Further delineation of the congenital form of X-linked dyskeratosis congenita (Hoyeraal-Hreidarsson syndrome). 1464 17


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