Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined seven pedigrees that include individuals with a recently described X-linked form of severe mental retardation associated with alpha-thalassemia (ATR-X syndrome). Using hematologic and molecular approaches, we have shown that intellectually normal female carriers of this syndrome may be identified by the presence of rare cells containing HbH inclusions in their peripheral blood and by an extremely skewed pattern of X inactivation seen in cells from a variety of tissues. Linkage analysis has localized the ATR-X locus to an interval of approximately 11 cM between the loci DXS106 and DXYS1X (Xq12-q21.31), with a peak LOD score of 5.4 (recombination fraction of 0) at DXS72. These findings provide the basis for genetic counseling, assessment of carrier risk, and prenatal diagnosis of the ATR-X syndrome. Furthermore, they represent an important step in developing strategies to understand how the mutant ATR-X allele causes mental handicap, dysmorphism, and down-regulation of the alpha-globin genes.
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PMID:X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome: localization to Xq12-q21.31 by X inactivation and linkage analysis. 141 55

The rare association of alpha thalassaemia and mental retardation has been described previously. Molecular studies of the alpha globin cluster in these cases have been heterogeneous, with some patients having large deletions while in others the alpha globin complex appears to be intact (non-deletional). The non-deletional cases form a distinct group whose features include severe mental retardation, haematological changes of haemoglobin H (Hb H) disease, developmental defects, and unusual patterns of inheritance. To date, five cases have been described with non-deletional alpha thalassaemia-mental retardation. We present here a further example of a young male of Northern European origin who appears to have the non-deletional form of the disease. Clinical features included severe mental retardation, Hb H disease, and developmental defects similar to those reported previously. DNA mapping, including pulsed field electrophoresis, showed no evidence of deletions within the alpha globin cluster. Karyotypic analysis indicated an increase in random breakage, which has been observed previously in one case of deletional alpha thalassaemia-mental retardation. Profuse Hb H bodies and Hb H on electrophoresis were consistent with Hb H disease. However, the latter was present at a relatively low level (1.6%) and, as well, the mean corpuscular volume (82.8 fl) and mean corpuscular haemoglobin (26.4 pg) were surprisingly high. Our findings are compared to other cases described with the non-deletional Hb H-mental retardation syndrome.
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PMID:Occurrence of the alpha thalassaemia-mental retardation syndrome (non-deletional type) in an Australian male. 223 51

Three male patients with X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome in a large French family are reported. Diagnosis was suspected on particular craniofacial dysmorphism associated with severe mental retardation and X-linked transmission. Hematological investigations, and in particular presence of Hb H inclusions in two of the boys, confirmed diagnosis. The clinical, hematological and radiological features are discussed in order to better define what appears to be a characteristic phenotype.
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PMID:X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome. Report of three male patients in a large French family. 816 24

We describe a pedigree presenting X-linked severe mental retardation associated with multiple congenital abnormalities and 46,XY gonadal dysgenesis, leading in one family member to female gender assignment. Female carriers are unaffected. The dysmorphic features are similar to those described in the alpha-thalassemia and mental retardation (ATR-X) syndrome, although there is no clinical evidence of alpha-thalassemia in this family. In addition, the family had other clinical features not previously observed in the ATR-X syndrome, including partial optic-nerve atrophy and partial ocular albinism. Mutations in a putative DNA helicase, termed XH2, have been reported to give rise to the ATR-X syndrome. We screened the XH2 gene for mutations in affected members of the family and identified a 4-bp deletion at an intron/exon boundary that removes an invariant 3' splice-acceptor site. The mutation cosegregates with the syndrome. The genomic deletion causes missplicing of the pre-mRNA, which results in the loss of 8 bp of coding sequence, thereby generating a frameshift and a downstream premature stop codon. Our finding increases the range of clinical features associated with mutations in the XH2 gene.
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PMID:A novel mutation in the putative DNA helicase XH2 is responsible for male-to-female sex reversal associated with an atypical form of the ATR-X syndrome. 865 Dec 95

X-linked alpha-thalassemia/mental retardation syndrome (ATR-X) is characterized by severe mental retardation, wide range of minor abnormalities, and association with an unusual form of alpha-thalassemia. Fifty patients in Caucasian origin have been reported. This is the second report of the syndrome demonstrated in Oriental patients.
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PMID:A Japanese patient with X-linked alpha-thalassemia/mental retardation syndrome: an additional case report. 899 69

The XNP/ATR-X gene is involved in several X-linked mental retardation phenotypes: the ATR-X syndrome, the Juberg-Marsidi syndrome, and some severe mental retardation phenotypes without alpha-thalassemia. Using a vectorette strategy, we have identified and sequenced the intron/exon boundaries of this gene. The gene is composed of 35 exons. It encodes a potential protein of 2492 amino acids. A search of the databases identified three zinc finger motifs within the 5' end of the gene. Expression analysis in different tissues indicated that an alternative splicing event that involves exon 6 is occurring. One of these alternatively spliced transcripts is predominantly expressed in embryonic tissues. These data led us to search for mutations in the 5' region in ATRX patients without other mutations in the 3' region. In one patient a mutation was found in which part of exon 7 was removed from the XNP transcript, as a result of a mutation creating a novel splice site that is substituted for the natural splice site. This new splicing event removed one zinc finger motif. This is the first example of a mutation in XNP within the 5' coding region. It suggests that mutations will be predominantly found in the helicase region as well as in the zinc finger regions and leads us to propose a large screening of additional patients.
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PMID:Determination of the genomic structure of the XNP/ATRX gene encoding a potential zinc finger helicase. 924 31

A 5-year-old male patient with X-linked alpha-thalassemia/mental retardation syndrome is reported. He showed multiple minor anomalies including characteristic facial abnormalities, alpha-thalassemia, severe mental retardation, and hypogonadism. Analysis of his hemoglobin by high performance liquid chromatography using an automated glycated hemoglobin analyzer revealed an abnormal peak. Identification of an abnormal peak by an automated glycated hemoglobin analyzer will aid in the diagnosis of patients with X-linked alpha-thalassemia/mental retardation syndrome.
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PMID:A case of X-linked alpha-thalassemia/mental retardation syndrome: analysis of hemoglobin by an automated glycated hemoglobin analyzer. 936 63

X-linked alpha-thalassemia/mental retardation syndrome (ATR-X), which was first reported by Wilkie, et al. in 1991, is a disorder with severe mental retardation, characteristic facial appearance, genital abnormalities, and mild form of alpha-thalassemia. At present, about 50 cases have been reported in the world, but few in Japan. We report 3 cases of this disorder in 2 families. All cases prefer a peculiar posture and show unique movements, such as self-induced vomiting or self-hanging, which can be diagnostic. ATR-X should be considered as a differential diagnosis in all male patients with severe mental retardation.
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PMID:[Three Japanese children with X-linked alpha-thalassemia/mental retardation syndrome (ATR-X)]. 969 21

A goal of molecular genetics is to understand the relationship between basic nuclear processes, epigenetic changes and the numerous proteins that orchestrate these effects. One such protein, ATRX, contains a highly conserved plant homeodomain (PHD)-like domain, present in many chromatin-associated proteins, and a carboxy-terminal domain which identifies it as a member of the SNF2 family of helicase/ATPases. Mutations in ATRX give rise to characteristic developmental abnormalities including severe mental retardation, facial dysmorphism, urogenital abnormalities and alpha-thalassaemia. This circumstantial evidence suggests that ATRX may act as a transcriptional regulator through an effect on chromatin. We have recently shown that ATRX is localized to pericentromeric heterochromatin during interphase and mitosis, suggesting that ATRX might exert other chromatin-mediated effects in the nucleus. Moreover, at metaphase, some ATRX is localized at or close to the ribosomal DNA (rDNA) arrays on the short arms of human acrocentric chromosomes. Here we show that mutations in ATRX give rise to changes in the pattern of methylation of several highly repeated sequences including the rDNA arrays, a Y-specific satellite and subtelomeric repeats. Our findings provide a potential link between the processes of chromatin remodelling, DNA methylation and gene expression in mammalian development.
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PMID:Mutations in ATRX, encoding a SWI/SNF-like protein, cause diverse changes in the pattern of DNA methylation. 1074 99

The molecular cause of the alpha-thalassemia/mental retardation syndrome (ATR-X) resides in mutations affecting the XNP/ATR-X gene. Recently molecular defects in the gene have been found in singular cases of a discrete number of X-linked mental retardation (XLMR). ATR-X-affected males are characterised by severe mental retardation, distinct facial dysmorphisms and genital abnormalities, besides a wide spectrum of pathological features and an extremely limited biological fitness. Given that molecular investigation of XNP/ATR-X mutations is made onerous by the length of the gene transcript, we carried out a prenatal diagnosis in a fetus at risk for ATR-X syndrome by initially determining the XNP/ATR-X gene haplotype before considering gene sequencing. Disease-associated haplotype analysis was performed selecting five genic (CA)n repeats that showed high heterozygosity (Het>0.7) in the general population. The fetus segregated an identical allelic pattern to that of the affected child of the family under investigation who shows features suggestive of the ATR-X syndrome. Subsequent mutational analysis of the gene revealed a novel IVS3+1G>T splicing mutation confirming the diagnosis.
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PMID:Prenatal diagnosis of ATR-X syndrome in a fetus with a new G>T splicing mutation in the XNP/ATR-X gene. 1155 11


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