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)

An infant with short stature and progressive skin lesions of cheeks and dorsum of the hands is described. Further problems such as recurrent diarrhoea and respiratory infections suggested zinc-deficiency, malabsorption-syndrome, Bloom syndrome and early Lupus Erythematosus respectively. Finally Rothmund-Thomson syndrome was diagnosed. This rare genetic disorder is characterized by variable expression of typical cutaneous changes, cataracts, skeletal anomalies, short stature, abnormal hair growth and defective nails and teeth, mental retardation, hypogonadism and a typical facial appearance.
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PMID:[An infant with short stature and red cheeks (Rothmund-Thomson syndrome)]. 177 48

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

Two monozygots twins had porokeratosis Mibelli and a deep mental retardation. The exploration of this nervous components is negative. The porokeratosis in one twin had in several sites the aspect of a skin's horn. The demonstration of the monozygotis was made by the same repartition of 16 characters (HLA, blood groups). The boys had the same aspect and the same skin disease. The twin method is discussed. The existence of the porokeratosis of Mibelli in two monozygotic twins is an argument for the genetic mechanism of the disease. The familial cases of porokeratose Mibelli reported by Bataillard, Civatte, Vigne, Bloom, have consistent features for an dominant autosomic transmission with variations in the penetrance and the expressivity of the skin disease.
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PMID:[Porokeratosis of Mibelli in two monozygotic twins (author's transl)]. 719 80

Sixty-eight children with malignant brain tumors were treated with the "8 in 1" chemotherapy protocol from 1986 to 1993 in Finland. The overall 5-year survival rate was 43%. Thirty-one children are still alive and tumor-free, and have been evaluated in the present study. Of these 31 children, 26% had hemi- or tetraplegia, 13% intractable seizures, and 30% attend special schools. The mean full scale (FS) IQ was 85 (range 45-138), 24% had an FSIQ value less than 70, and 36% more than 90. One-half of the survivors were placed in Bloom's group I or II, are able to lead an active life, and have only mild neurologic disabilities. In the other, neurologic late complications accumulated and these children were relegated to Bloom's group III or IV, with major disabilities such as hemiplegia, intractable epilepsy, or mental retardation. The most important prognostic factors were severe perioperative complications, young age at diagnosis, and cranial irradiation.
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PMID:Neuropsychologic late effects in children with malignant brain tumors treated with surgery, radiotherapy and "8 in 1" chemotherapy. 883 71

A search of the Human Genome Sciences database of expressed sequence-tagged DNA fragments, for sequences containing homology to known yeast DNA recombination and repair genes, yielded a cDNA fragment with high homology to RAD54. Here we describe the complete cDNA sequence and the characterization of the genomic locus coding for the human homologue of the yeast RAD54 gene (hRAD54). The yeast RAD54 belongs to the RAD52 epistasis group and appears to be involved in both DNA recombination and repair. The hRAD54 gene maps to chromosome 1p32 in a region of frequent loss of heterozygosity in breast tumors and encodes a protein of M(r) 93,000 that displays 52% identity to the yeast RAD54 protein. The hRAD54 protein sequence additionally contains all seven of the consensus segments of a superfamily of proteins with presumed or proven DNA helicase activity. Mutations in genes with consensus helicase homology have been found in cancer-prone syndromes such as xeroderma pigmentosum and Bloom syndrome as well as Werner's syndrome, in which patients age prematurely, and the X-linked mental retardation with alpha-thalassemia syndrome, ATR-X. We have examined the hRAD54 gene in several breast tumors and breast tumor cell lines and, although the gene region appears to be deleted in several tumors, at present we have found no coding sequence mutations.
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PMID:Characterization of the human homologue of RAD54: a gene located on chromosome 1p32 at a region of high loss of heterozygosity in breast tumors. 919 13

Six known or predicted helicases that are mutated in human syndromes are now recognized. These syndromes include xeroderma pigmentosum, Cockayne's syndrome, trichothiodystrophy, Bloom's syndrome, Werner's syndrome, and alpha-thalassemia mental retardation on the X chromosome. The clinical abnormalities in these syndromes cover a broad spectrum, pointing to different cellular processes of DNA manipulation that are defective in these syndromes.
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PMID:DNA helicases in inherited human disorders. 922 11

Sixty-four children with malignant brain tumours diagnosed at less than 3 years of age were reported to the Finnish Cancer Registry from 1975 to 1993. The survival rate has improved significantly: the 5-year survival rate was 26% for all children, 13% for children diagnosed during 1975-85 (n = 30) and 40% for those diagnosed during 1986-93 (n = 34). Of the surviving children in 1986-93, 43% were categorized in Bloom's group I or II and could lead active lives without major disabilities. The remaining children had severe neurologic late complications, such as hemiplegia, intractable seizures, and mental retardation.
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PMID:Improving outcome of malignant brain tumours in very young children: a population-based study in Finland during 1975-93. 924 Aug 80

Complex chromosome rearrangements (CCRs) are currently defined as structural genome variations that involve more than 2 chromosome breaks and result in exchanges of chromosomal segments. They are thought to be extremely rare, but their detection rate is rising because of improvements in molecular cytogenetic technology. Their population frequency is also underestimated, since many CCRs may not elicit a phenotypic effect. CCRs may be the result of fork stalling and template switching, microhomology-mediated break-induced repair, breakage-fusion-bridge cycles, or chromothripsis. Patients with chromosomal instability syndromes show elevated rates of CCRs due to impaired DNA double-strand break responses during meiosis. Therefore, the putative functions of the proteins encoded by ATM, BLM, WRN, ATR, MRE11, NBS1, and RAD51 in preventing CCRs are discussed. CCRs may exert a pathogenic effect by either (1) gene dosage-dependent mechanisms, e.g. haploinsufficiency, (2) mechanisms based on disruption of the genomic architecture, such that genes, parts of genes or regulatory elements are truncated, fused or relocated and thus their interactions disturbed - these mechanisms will predominantly affect gene expression - or (3) mixed mutation mechanisms in which a CCR on one chromosome is combined with a different type of mutation on the other chromosome. Such inferred mechanisms of pathogenicity need corroboration by mRNA sequencing. Also, future studies with in vitro models, such as inducible pluripotent stem cells from patients with CCRs, and transgenic model organisms should substantiate current inferences regarding putative pathogenic effects of CCRs. The ramifications of the growing body of information on CCRs for clinical and experimental genetics and future treatment modalities are briefly illustrated with 2 cases, one of which suggests KDM4C (JMJD2C) as a novel candidate gene for mental retardation.
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PMID:Mechanisms of Origin, Phenotypic Effects and Diagnostic Implications of Complex Chromosome Rearrangements. 2673 13

The histone demethylase PHF8 has been implicated in multiple pathological disorders, including X-linked mental retardation and tumorigenesis. However, it is not clear how the abundance and function of PHF8 are regulated. Here, we report that PHF8 physically associates with the deubiquitinase USP7. Specifically, we demonstrated that USP7 promotes deubiquitination and stabilization of PHF8, leading to the upregulation of a group of genes, including cyclin A2, that are critical for cell growth and proliferation. The USP7-encoding gene was also transcriptionally regulated by PHF8, via positive feedback. USP7 was overexpressed in breast carcinomas, and the level of expression positively correlated with expression of PHF8 and cyclin A2 and with the histological grade of breast cancer. We showed that USP7 promotes breast carcinogenesis by stabilizing PHF8 and upregulating cyclin A2 and that the interaction between USP7 and PHF8 is augmented during DNA damage. Moreover, USP7-promoted PHF8 stabilization conferred cellular resistance to genotoxic insults and was required for the recruitment of BLM and KU70, which are both essential for DNA double-strand break repair. Our study mechanistically links USP7 to epigenetic regulation and DNA repair. Moreover, these data support the pursuit of USP7 and PHF8 as potential targets for breast cancer intervention, especially in combination with chemo- or radiotherapies.
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PMID:Stabilization of histone demethylase PHF8 by USP7 promotes breast carcinogenesis. 2718 83