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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hereditary gastrointestinal polyposis syndromes can be divided into adenomatous and hamartomatous types. Familial adenomatous polyposis coli (FAPC) is the prototype adenomatous polyposis syndrome and is defined by the autosomal dominant transmission of multiple (more than 100) colorectal adenomas. Virtually all affected patients develop colorectal carcinoma if untreated. Adenomas may develop also in the stomach and small bowel in FAPC patients, but the incidence of carcinoma in these sites is low. A variety of extracolonic manifestations has been reported in FAPC, with the name Gardner's syndrome applied to kindreds with osteomas of the skull and mandible, multiple epidermal cysts, and other skin and soft-tissue lesions. In Turcot's syndrome, brain tumors are present. The distinction between Gardner's and Turcot's syndromes and classical FAPC has become blurred because of marked overlap between them; some authorities consider them to be varying manifestations of a single genetic defect. The hamartomatous polyposes include Peutz-Jeghers syndrome, familial juvenile polyposis, Cowden's disease, intestinal ganglioneuromatosis, and the Ruvalcaba-Myrhe-Smith syndrome. The incidence of gastrointestinal cancer in patients with Peutz-Jeghers syndrome and familial juvenile polyposis exceeds that in the normal population, but is relatively low. In Cowden's disease, the gastrointestinal tract may be the site of multiple hamartomas, but there is no associated increase in the incidence of gastrointestinal cancers; instead, there is an increased incidence of carcinoma of the breast and thyroid. Intestinal ganglioneuromatosis occurs in von Recklinghausen's disease, in association with multiple endocrine neoplasia, type 2b, or as an isolated abnormality. Patients with ganglioneuromatosis do not appear to have an increased risk of developing gastrointestinal cancer. Ruvalcaba-Myrhe-Smith syndrome comprises macrocephaly, mental deficiency, an unusual craniofacial appearance, hamartomatous intestinal polyposis, and pigmented macules on the penis. No increased risk of developing cancer has been identified in the few reported cases.
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PMID:Hereditary gastrointestinal polyposis syndromes. 302 15

Otorhinolaryngological manifestations of 13 patients with von Recklinghausen's disease appearing at Lagos University Teaching Hospital over a five-year period have been studied. Among patients with ENT manifestations of the disease, the most common general features exhibited were cutaneous neurofibromas (100 per cent), headache (69.23 per cent) and pruritus (46.15 per cent). But the head and neck findings included external meatal canal stenosis (30.77 per cent), conductive deafness (30.77 per cent), nasal discharge (30.77 per cent), cranial nerve involvement (30.77 per cent) and disfigurement of the soft tissues of the face (30.77 per cent). Involvement of pinna (23.31 per cent), rhinolalia aperta (15.38 per cent), mental retardation (15.38 per cent) and pharyngeal swelling (7.69 per cent) also featured. Clinically detectable bilateral acoustic neurofibromas in adults or astrocytomas in children were not found in this series. Involvement of the frontoparietal bone (7.65 per cent) presented with skull bossing which had to be differentiated from that due to sickle cell disease in the African. There was also a singular case of phrenic nerve involvement. However, malignancy occurred in one (7.69 per cent) of these patients. Thus, it is important always to follow-up these patients closely so as to detect malignant transformation in time.
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PMID:Otorhinolaryngological manifestations of von Recklinghausen's disease in Nigerians. 308 May 40

Further studies on a family with the N syndrome, a multiple congenital anomaly/mental retardation syndrome first described by Hess et al in 1974, showed increased chromosome breakage in the affected brothers and in their unaffected mother, all 3 of whom died of lymphoid malignancy. It is suggested that the N syndrome is the result of an X-linked recessive mutation that produces a characteristic MCA/MR syndrome and chromosome instability. We postulate that this chromosome instability in the lymphoid cells of hemizygotes and in approximately half of the lymphoid cells of the heterozygote predisposes to a specific form of lymphoid malignancy.
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PMID:Updating the N syndrome: occurrence of lymphoid malignancy and possible association with an increased rate of chromosome breakage. 313 Aug 73

Fragile X [Fra(X)] syndrome is an example of a heritable fragility syndrome associated with mental retardation. It is characterized by a fragile site on the X chromosome at Xq27-28. There have recently been three reports of malignant solid tumors associated with Fra(X) syndrome. We describe the first case of a hematologic malignancy [T-cell acute lymphocytic leukemia (ALL)] in a patient with Fra(X) syndrome. The possibility of a predisposition to malignancy in Fra(X) is discussed.
Cancer 1988 Dec 01
PMID:Fragile X syndrome and acute lymphoblastic leukemia. 317 54

Cancer risk models and their relationship to ionizing radiation are discussed. There are many model assumptions and risk factors that have a large quantitative impact on the cancer risk estimates. Other health end points such as mental retardation may be an even more serious risk than cancer for those with in utero exposures.
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PMID:Radiation risk estimation models. 331 58

Radiation doses absorbed by the uterus, ovary, testicle and active bone marrow are computed for cervical, thoracic, lumbar, full spine and chest series performed under typical office conditions. Assuming a nonthreshold, linear relationship between dose and radiogenic effect, the computed tissue-specific doses are used to estimate the probability that each X-ray series might enhance the statistical probability of occurrence of an adult leukemia fatality of the irradiated patient; a childhood leukemia, mental retardation or cancer fatality as a result of fetal irradiation; or a variety of sex cell chromosomal aberrations in irradiated patients. It is concluded that the greatest hazard to active bone marrow, the uterus and the gonads is posed by lumbar and full spine radiography and that the need to adequately justify such exposure is mandatory; furthermore, in these series, irradiation of the ovary is 10 times as great as that of the testicle. Lumbar radiographic examinations can be made significantly safer by the elimination of the lumbosacral spot view.
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PMID:Organ-specific dosimetry in spinal radiography: an analysis of genetic and somatic effects. 335 98

An analysis of the dose response within the low-dose range (as here defined, doses of less than 50 cGy (50 rad) was conducted among A-bomb survivors in the ABCC-RERF cohort in an attempt to detect the phenomenon of radiation hormesis, if it is present. These studies include as endpoints cancer mortality, cancer incidence, the frequency of cells with chromosomal aberrations, the phytohemagglutinin response of peripheral lymphocytes and the frequency of mental retardation among survivors exposed in utero. In general, the dose response for these indices of radiation damage varied among comparison groups within the low-dose range, but failed to suggest the existence of radiation hormesis.
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PMID:Dose-response analyses among atomic bomb survivors exposed to low-level radiation. 357 Aug 2

The nevus sebaceus of Jadassohn (SNJ) is a congenitally-occurring, hamartomatous disorder of the skin and its adnexa of infrequent occurrence. This presentation of five cases emphasizes the smooth, waxy, yellow-brown lesion's progression into a thickened sebaceous tumor of premalignant predilection. The incidence of neoplastic degeneration of these hamartomatous nevi may be as high as 30% with the capacity of metastasis occasionally reported. Because of malignancy risks as well as cosmetic considerations, early surgical removal is recommended. Previously unreported problems of dysphagia and malnutrition secondary to pulsion diverticulum at the esophageal inlet and cleft palate, obliterative aural stenosis with associated conductive hearing loss are documented. Regardless of SNJ's occurrence as either an isolated lesion or as the fully developed syndrome, including mental retardation and epilepsy, this congenital malformation of the skin, its hair, and sebaceous glands presents rare and histologically intriguing problems for the practitioner.
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PMID:Nevus sebaceus of Jadassohn: the head and neck manifestations. 361 88

The fragile sites of human chromosomes are specific sites that are characterized by a tendency to show gaps, multiradial figures, acentric fragments, and deleted chromosomes on microscopy. These characteristics seem to reflect an inherent fragility at the site, although the underlying biochemical cause of fragile sites is unknown. Investigators have proposed several categories of fragile sites: "rare" or "heritable," "common," and "constitutive." Although the clinical significance of most fragile sites is unknown, fragile site Xq27.3 is associated with one form of X-linked mental retardation. In this article, the three types of chromosome fragile sites are described, and their possible relevance to chromosomal breakage that results in birth defects or cancer is discussed.
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PMID:Fragile sites on human chromosomes: description and clinical significance. 389 34

Fragile sites appear to be associated with a higher rate of breakage and specific chromosome rearrangement in cancer. A fragile site located on the human X chromosome at band Xq27 is known to be expressed under conditions of thymidylate stress. In order to obtain a model cell system suitable for studying the mechanism of expression of the fragile X site, interspecific somatic cell hybrids were constructed by cell fusion between human skin fibroblasts derived from a male patient with fragile X-linked mental retardation and thymidylate synthase-negative mouse mutant cells. The primary isolated hybrid clones were thymidine-prototrophic and expressed the fragile X site under conditions of thymidylate stress caused by 5-fluoro-2'-deoxyuridine treatment. In a thymidine-auxotrophic hybrid clone segregated from a thymidine-prototrophic hybrid clone, the expression of the fragile X site was induced in thymidylate stress conditions achieved by thymidine deprivation alone. This result provides direct evidence that expression of the fragile X site is dependent upon a lowered supply of thymidylate.
Jpn J Cancer Res 1985 Oct
PMID:Expression of fragile site on the human X chromosome in somatic cell hybrids between human fragile X cells and thymidylate synthase-negative mouse mutant cells. 393 28


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