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)

Two sibs with non-deletional alpha thalassaemia and mental retardation (ATR-X) have been ascertained showing variable neurological features. The proband had a complex neurological picture with recurrent apnoea, complex partial seizures, and prolonged periods of semiconsciousness between 12 and 17 months of age. Episodes of spontaneous laughter were also a feature. An EEG was initially normal. Hb H inclusions were present but rare in this family. The sole genital anomaly was deficiency of the foreskin, a feature not previously described in ATR-X.
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PMID:X linked mental retardation with non-deletional alpha thalassaemia (ATR-X): further delineation of the phenotype. 801 76

A novel form of severe, X linked mental retardation associated with alpha thalassaemia (ATR-X syndrome) has recently been described. Two affected cousins are described, one of whom has an unusually mild haematological phenotype. HbH inclusions, which are the hallmark of this disease, were only detected in the peripheral red blood cells after repeated observations.
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PMID:Alpha thalassaemia mental retardation (ATR-X): an atypical family. 801 70

Linkage analysis was performed in a three generation family with three males affected by the recently delineated X-linked form of alpha-thalassemia/mental retardation syndrome (ATR-X). Results are in agreement with the linkage study reported by Gibbons et al in 1992 and further confirm that the ATR-X gene is located in proximal Xq. Positive LOD scores were obtained for several markers situated in the pericentromeric region. A maximum LOD score of 2.09 at a recombination fraction of 0 was obtained for DXS453 located at the boundary q12-q13.1. The nearest flanking loci demonstrating recombination with the disease locus were AR at Xq11.2-q12 on the centromeric side and DXS72 at Xq21.1 on the telomeric side. Consequently the authors were able to reduce the previously defined candidate region for the gene location. Their results are compatible with a distal boundary at Xq21.1 instead of q21.31.
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PMID:X-linked alpha-thalassemia/mental retardation syndrome. Linkage analysis in a new family further supports localization in proximal Xq. 816 23

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 have previously described a series of patients in whom the deletion of 1-2 megabases (Mb) of DNA from the tip of the short arm of chromosome 16 (band 16p13.3) is associated with alpha-thalassemia/mental retardation syndrome (ATR-16). We now show that one of these patients has a de novo truncation of the terminal 2 Mb of chromosome 16p and that telomeric sequence (TTAGGG)n has been added at the site of breakage. This suggests that the chromosomal break, which is paternal in origin and which probably arose at meiosis, has been stabilized in vivo by the direct addition of the telomeric sequence. Sequence comparisons of this breakpoint with that of a previously described chromosomal truncation (alpha alpha)TI do not reveal extensive sequence homology. However, both breakpoints show minimal complementarity (3-4 bp) to the proposed RNA template of human telomerase at the site at which telomere repeats have been added. Unlike previously characterized individuals with ATR-16, the clinical features of this patient appear to be solely due to monosomy for the terminal portion of 16p13.3. The identification of further patients with "pure" monosomy for the tip of chromosome 16p will be important for defining the loci contributing to the phenotype of this syndrome.
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PMID:De novo truncation of chromosome 16p and healing with (TTAGGG)n in the alpha-thalassemia/mental retardation syndrome (ATR-16). 846 Jun 33

Mental handicap is a common clinical problem that has been a relatively neglected area of research. Though the causes are varied and complex, molecular biologists are making progress in understanding the mechanisms in some cases, particularly where there are distinguishing phenotypic or genetic markers. The fortuitous association of alpha thalassaemia with a form of mental retardation has allowed us to define a specific X-linked syndrome (ATR-X). Positional cloning was used to define a disease interval and examination of candidate genes demonstrated that mutations in a gene, XH2, showing homology to the SNF2 superfamily were responsible for this syndrome. The complex ATR-X phenotype suggests that this gene, when mutated, down-regulates the expression of several genes including the alpha-globin genes indicating that it could be a global transcriptional regulator. It is conceivable that this mechanism is involved in other forms of syndromal mental retardation.
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PMID:Syndromal mental retardation due to mutations in a regulator of gene expression. 854 68

The chromosome-16 and the X-chromosome forms of alpha-thalassemia--ATR-16 and ATR-X--exemplify 2 important causes of syndromal mental retardation. ATR-16 is a contiguous gene syndrome which arises from loss of DNA from the tip of chromosome 16p13.3 by truncation, interstitial deletion, or unbalanced translocation. It provided the first example of a chromosome translocation that could be detected by molecular analysis but not conventional cytogenetics. It also provided the first example of a telomeric truncation giving rise to a complex genetic syndrome. In contrast ATR-X appears to be due to mutations in a trans-acting factor that regulates gene expression. Mutations in transcription factors have recently been identified in a number of genetic diseases (for example, Denys-Drash syndrome, WT1 [19]; pituitary dwarfism, PIT1 [16]; Rubinstein-Taybi syndrome, CBP [20]. Not only is this mechanism proving to be an important cause of complex syndromes but it is providing new perspectives on certain developmental pathways. XH2 may not be a classical transcription factor but it is certainly involved in the regulation of gene expression, exerting its effects on several different genes. It seems likely that other mutations in this class of regulatory proteins will be found in patients with complex disorders including mental retardation. In broader terms the 2 mechanisms described here may prove to be responsible for a significant proportion of mental retardation. However, without a feature such as alpha-thalassemia to pinpoint the area of genome or pathways involved it may prove difficult to identify other, similarly affected genes underlying other forms of mental retardation. As the human genome project and rapid genome analysis evolve this problem should become less of an obstacle. In the meantime, it is very worthwhile to continue looking for unusual clinical associations that may point to critical genes underlying human genetic disorders.
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PMID:The alpha-thalassemia/mental retardation syndromes. 860 26

We have previously reported the isolation of a gene from Xq13 that codes for a putative regulator of transcription (XNP) and has now been shown to be the gene involved in the X-linked alpha-thalassemia with mental retardation (ATR-X) syndrome. The widespread expression and numerous domains present in the putative protein suggest that this gene could be involved in other phenotypes. The predominant expression of the gene in the developing brain, as well as its association with neuron differentiation, indicates that mutations of this gene might result in a mental retardation (MR) phenotype. In this paper we present a family with a splice junction mutation in XNP that results in the skipping of an exon and in the introduction of a stop codon in the middle of the XNP-coding sequence. Only the abnormal transcript is expressed in two first cousins presenting the classic ATR-X phenotype (with alpha-thalassemia and HbH inclusions). In a distant cousin presenting a similar dysmorphic MR phenotype but not having thalassemia, approximately 30% of the XNP transcripts are normal. These data demonstrate that the mode of action of the XNP gene product on globin expression is distinct from its mode of action in brain development and facial morphogenesis and suggest that other dysmorphic mental retardation phenotypes, such as Juberg-Marsidi or some sporadic cases of Coffin-Lowry, could be due to mutations in XNP.
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PMID:Splicing mutation in the ATR-X gene can lead to a dysmorphic mental retardation phenotype without alpha-thalassemia. 864 9

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

It was shown recently that mutations of the ATRX gene give rise to a severe, X-linked form of syndromal mental retardation associated with alpha thalassaemia (ATR-X syndrome). In this study, we have characterised the full-length cDNA and predicted structure of the ATRX protein. Comparative analysis shows that it is an entirely new member of the SNF2 subgroup of a superfamily of proteins with similar ATPase and helicase domains. ATRX probably acts as a regulator of gene expression. Definition of its genomic structure enabled us to identify four novel splicing defects by screening 52 affected individuals. Correlation between these and previously identified mutations with variations in the ATR-X phenotype provides insights into the pathophysiology of this disease and the normal role of the ATRX protein in vivo.
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PMID:ATRX encodes a novel member of the SNF2 family of proteins: mutations point to a common mechanism underlying the ATR-X syndrome. 896 41


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