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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Non-random tumour-specific chromosomal abnormalities have been observed in cells of many different human tumours. In Wilms' tumour (WT) and retinoblastoma, a chromosomal deletion occurs germinally or somatically and has been considered an important step in tumour development. One class of potential cellular transforming genes comprises the cellular homologues of the transforming genes of highly oncogenic retroviruses. A remarkable concordance between the chromosomal location of human cellular oncogenes and the breakpoints involved in acquired chromosomal translocations is becoming apparent in various cancers: the oncogenes c-mos, c-myc and c-abl are located at the breakpoints that occur in acute myeloblastic leukaemia, Burkitt's lymphoma and chronic myelocytic leukaemia respectively. Thus when the oncogene c-Ha-ras1 was localized to the short arm of human chromosome 11 (refs 6-8; region 11p11 leads to p15 and not 11p13 as stated in ref. 5), it was proposed as a possible aetiological agent in the aniridia-WT association (AWTA) that results from a deletion of 11p13 (although a transforming gene recently isolated from a WT cell line (G401) was shown not to be homologous to either c-Ha-ras or c-Ki-ras9). We have now looked for deletion or rearrangement of c-Ha-ras1 in the DNA from four subjects with del(11p13)-associated predisposition to Wilms' tumour, aniridia, genitourinary abnormalities and mental retardation. We report here that in no case is c-Ha-ras1 deleted, and we have further refined its location to 11p15.1 leads to 11p15.5. On the basis of enzyme studies and direct gene dosage determination for c-Ha-ras1 and beta-globin in neoplastic and non-neoplastic tissues from one patient, we conclude that deletion of the normal counterpart of 11p cannot account for the development of the tumour.
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PMID:c-Ha-ras1 is not deleted in aniridia-Wilms' tumour association. 631 28

A del(13)(q13q21.1) was found in a patient with bilateral retinoblastoma and mental retardation. The father was carrier of an ins(16;13)(q12.2;q13q21.1) which also was present in several other family members, and responsible for another case of del (13q)-retinoblastoma and two cases of trisomy for the inserted segment. This second del(13q) patient was also carrier of a balanced t(11;22).
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PMID:Two cases of del(13q)-retinoblastoma and two cases of partial trisomy due to a familial insertion. 631 32

One of the most provocative findings in tumour biology is the relationship between chromosomal changes and embryonal cancers in children. For example, children with the rare paediatric syndrome AGR triad (aniridia, genito-urinary abnormalities and mental retardation) often develop Wilms' tumours at a very early age and carry a germ-line deletion on the short arm of chromosome 11 (11p13). It has been suggested that the germ-line deletion 11p is the first of two or more steps to cancer in AGR children. If this were true, one might expect a similar deletion to arise somatically in the far more common isolated Wilms' tumours of children without AGR, as suggested by Knudson from epidemiological data. However, a chromosomal deletion on 11p was observed in only two of five such cases, while it was absent or seen inconsistently in others. We have now used a molecular genetic approach to determine whether Wilms' tumour cells possess somatic alterations at 11p loci. We have found somatic deletions of specific genes in four of six Wilms' tumours. Surprisingly, in all four cases, the deletions were associated with duplications leading to homozygosity of the non-deleted alleles in the tumour cells. As analogous observations were recently reported in retinoblastoma, the genetic events reported here may underlie the development of many such embryonal tumours in children.
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PMID:Somatic deletion and duplication of genes on chromosome 11 in Wilms' tumours. 632 39

Human chromosome disease arises from a change in the number or structure of one or more chromosomes. The multiple genes represented in the duplicated or deleted chromosomes are not usually defective and any systemic abnormalities can be attributed to a change in gene dosage. Banding techniques are now commonly used to identify each chromosome and the specific chromosome duplication and deletion and structural rearrangements can now be identified unambiguously. Most ocular abnormalities have occurred in patients with chromosomal defects. Major ocular abnormalities, such as anophthalmia, cyclopia, retinoblastoma, microphthalmia, corneal opacities, coloboma, cataracts, intraocular cartilage, retinal dysplasia and absent optic nerves; and, minor abnormalities, such as ptosis, abnormal eyelid fissures, and Brushfield spots are present in individuals with abnormal chromosomes. The chromosome errors are usually present in all somatic tissues. consequently, multiple tissue abnormalities would be expected in most patients with chromosome abnormalities. Mental retardation is very common in those patients with abnormalities of autosomes. Therefore, it is unlikely that an isolated single clinical or histopathological ocular abnormality will be the result of a chromosome error. However, if the individual has multiple systemic abnormalities, then a chromosome error can be considered reasonably. Any chromosome disorder can be identified correctly by an appropriate banding chromosome determination on the affected individuals. With the possible exception of the association of 13q 14- and retinoblastoma, there does not appear to be any pathognomonic ocular abnormalities that occur in individuals with chromosome errors.
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PMID:Classification of chromosomal eye syndromes. 645 12

To our knowledge, 20 cases of retinoblastoma associated with a chromosome #13 aberration have been reported. The present study utilized high-resolution prophase banding analysis of 12 additional retinoblastoma patients to determine the occurrence of chromosome aberrations and identify consistently associated clinical abnormalities. Six male and six female patients were studied representing seven cases of bilateral and five cases of unilateral retinoblastoma. One case of unilateral and two cases of bilateral retinoblastoma and detectable cytogenetic abnormalities, all involving an interstitial deletion of 13q14 on the long arm of one chromosome #13. In all five unilateral cases the tumor manifested in the left orbit, and in all seven bilateral cases the left eye was at a more malignantly advanced stage than the right eye. All three cases with a chromosome abnormality had varying degrees of developmental and/or mental retardation, along with at least one other congenital abnormality. In addition to the 12 cases of retinoblastoma, a patient with severe ophthalmologic abnormalities and mild congenital anomalies was studied by the prophase banding technique and found to be partially trisomic for the 13q14 region with gene loci for optic development and indicate that cytogenetic abnormalities may occur even more frequently in retinoblastoma than indicated by the small number of cases reported in the literature.
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PMID:Retinoblastoma and its association with a deletion in chromosome #13: a survey using high-resolution chromosome techniques. 710 85

Two cases of association of unilateral and bilateral retinoblastoma, respectively, with interstitial deletions of long arms of chromosome 13 are presented. The clinical pictures of both children corresponded to the moderate extent of the deletions, with both somatic and mental retardation in both children, and mild phenotypic manifestations (hypertelorism, slight epicanthi, mild facial hirsutism, and partial syndactyly in the child with unilateral retinoblastoma). Opinions concerning the association of chromosome 13 deletion with retinoblastoma are discussed.
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PMID:Retinoblastoma and chromosome 13 deletion. 716 Nov 17

A partial monosomy 13 by interstitial deletion was found in the complement of a patient with mental retardation and mild dysmorphic features. Due to the involvement of band q14 in the deletion, an ocular investigation was performed which showed the presence of a retinoblastoma in a preclinical stage. The different patterns of retinoblastoma inheritance are discussed and the importance of an accurate clinical investigation is stressed in all cases in whom chromosomal aberration is known to be associated with neoplasias.
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PMID:Chromosome 13 deletion syndrome: report of a new case and discussion of the different etiologic patterns of retinoblastoma. 724 83

The outcomes for five patients with retinoblastoma and constitutional chromosomal abnormalities involving the long arm of chromosome 13 are reported. All patients demonstrated developmental delay and mental retardation. Four of these patients are alive 23, 21, 15, and 1 year from diagnosis; one died of pneumonia with septicemia. Each of the four survivors has, with aging, shown hypotonia, mutism, contractures, and inability to function independently.
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PMID:Outcome for patients with constitutional 13q chromosomal abnormalities and retinoblastoma. 782 49

The Wilms tumour (WT1) gene was first localized through its deletion in individuals with the WAGR syndrome (Wilms tumour, aniridia, genitourinary abnormalities and mental retardation). Such individuals have a 30-50% lifetime risk of developing Wilms tumour and carry constitutional interstitial deletions of chromosome 11p13, including the WT1 gene. Second primary tumours occurring in such individuals might also be related to their genetic predisposition to cancer, as shown for hereditary retinoblastoma. We have found a mutation in the zinc finger region of the remaining WT1 allele in a case of acute myeloid leukaemia developing in a Wilms tumour survivor with the WAGR syndrome. This mutation would be predicted to disrupt DNA binding by this developmentally regulated transcription factor. This finding implicates the WT1 gene in the regulation of myelopoiesis and suggests that WT1 mutations may be found in some sporadic leukaemias.
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PMID:The Wilms tumour (WT1) gene is mutated in a secondary leukaemia in a WAGR patient. 783 22

In screens for genetic modifiers of lin-35/Rb, the C. elegans retinoblastoma protein (Rb) homolog, we have identified a mutation in xnp-1. Mutations in xnp-1, including a presumed null allele, are viable and, in general, appear indistinguishable from the wild type. In contrast, xnp-1 lin-35 double mutants are typically sterile and exhibit severe defects in gonadal development. Analyses of the abnormal gonads indicate a defect in the lineages that generate cells of the sheath and spermatheca. xnp-1 encodes the C. elegans homolog of ATR-X, a human disease gene associated with severe forms of mental retardation and urogenital developmental defects. xnp-1/ATR-X is a member of the Swi2/Snf2 family of ATP-dependent DEAD/DEAH box helicases, which function in nucleosome remodeling and transcriptional regulation. Expression of an xnp-1 Colon, two colons GFP promoter fusion is detected throughout C. elegans development in several cell types including neurons and cells of the somatic gonad. Our findings demonstrate a new biological role for Rb family members in somatic gonad development and implicate lin-35 in the execution of multiple cell fates in C. elegans. In addition, our results suggest a possible conserved function for xnp-1/ATR-X in gonadal development across species.
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PMID:lin-35/Rb and xnp-1/ATR-X function redundantly to control somatic gonad development in C. elegans. 1532 17


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