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Query: UMLS:C0265264 (HOS)
 1,119 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Holt-Oram syndrome is a developmental disorder affecting the heart and upper limb, the gene for which was mapped to chromosome 12 two years ago. We have now identified a gene for this disorder (HOS1). The gene (TBX5) is a member of the Brachyury (T) family corresponding to the mouse Tbx5 gene. We have identified six mutations, three in HOS families and three in sporadic HOS cases. Each of the mutations introduces a premature stop codon in the TBX5 gene product. Tissue in situ hybridization studies on human embryos from days 26 to 52 of gestation reveal expression of TBX5 in heart and limb, consistent with a role in human embryonic development.
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PMID:Holt-Oram syndrome is caused by mutations in TBX5, a member of the Brachyury (T) gene family. 898 64

Holt-Oram syndrome is characterized by upper limb malformations and cardiac septation defects. Here, we demonstrate that mutations in the human TBX5 gene underlie this disorder. TBX5 was cloned from the disease locus on human chromosome 12q24.1 and identified as a member of the T-box transcription factor family. A nonsense mutation in TBX5 causes Holt-Oram syndrome in affected members of one family; a TBX5 missense mutation was identified in affected members of another. We conclude that TBX5 is critical for limb and heart development and suggest that haploinsufficiency of TBX5 causes Holt-Oram syndrome.
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PMID:Mutations in human TBX5 [corrected] cause limb and cardiac malformation in Holt-Oram syndrome. 898 65

Ulnar-mammary syndrome is a rare pleiotropic disorder affecting limb, apocrine gland, tooth and genital development. We demonstrate that mutations in human TBX3, a member of the T-box gene family, cause ulnar-mammary syndrome in two families. Each mutation (a single nucleotide deletion and a splice-site mutation) is predicted to cause haploinsufficiency of TBX3, implying that critical levels of this transcription factor are required for morphogenesis of several organs. Limb abnormalities of ulnar-mammary syndrome involve posterior elements. Mutations in TBX5, a related and linked gene, cause anterior limb abnormalities in Holt-Oram syndrome. We suggest that during the evolution of TBX3 and TBX5 from a common ancestral gene, each has acquired specific yet complementary roles in patterning the mammalian upper limb.
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PMID:Mutations in human TBX3 alter limb, apocrine and genital development in ulnar-mammary syndrome. 920 1

Brachyury, or T, is the founder member of a family of transcription factors that share the so-called T-box-a 200 amino acid DNA-binding domain. Recent work has addressed the regulation of Brachyury expression and its function in the embryo. New T-box family members have been found in vertebrate and invertebrate embryos and the importance of this gene family is illustrated by the discovery that mutations in human TBX5 are responsible for Holt-Oram syndrome, which is characterised by abnormalities in heart and forelimb development.
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PMID:Brachyury and the T-box genes. 930 77

TBX2 is a member of a recently discovered gene family of transcription factors, named T-box genes after the Brachyury or T gene. Mutations in two of these family members, TBX5 and TBX3, have recently been shown to be responsible for the congenital abnormalities associated with Holt Oram syndrome and ulnar-mammary syndrome respectively, while mutations in T-box genes in other species also result in developmental abnormalities in the tissues where the gene is normally expressed. Thus, it likely that other T-box genes are responsible for additional human developmental anomalies. Here we report the exon/intron boundaries of TBX2 and a polymorphism within intron 2 of TBX2 that should be useful for exploring the involvement of this gene in human genetic disease. We further note that the exon/intron boundaries of TBX2 are highly conserved within the T-box domain with those of both T and TBX5, as well as with a new human T-box gene and more distantly related genes from Caenorhabditis elegans and Drosophila. This observation should facilitate the analysis of the genomic structure of other members of this gene family. It is also of interest that several members of this gene family have an additional intron that is variably present within members of at least two different lineages of the T-box family. This observation has implications regarding the evolution of T-box genes.
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PMID:Genomic structure of TBX2 indicates conservation with distantly related T-box genes. 943 49

T-box genes, in all metazoans studied from nematode to man, exist in small gene families. They encode transcription factors with a novel, large, and highly conserved DNA binding domain termed the T-domain. In all cases studied, T-box genes have important developmental roles. Two familial diseases, Holt-Oram syndrome and ulnar-mammary syndrome, were recently shown to be caused by mutations in the human T-box genes TBX5 and TBX3, respectively. T-box genes were first identified in Drosophila and mouse. Two of the three known Drosophila T-box genes show a close sequence homology to mammalian genes. Similarities in the phenotypes of fly and mammalian mutants can be taken as evidence of functional conservation. We report here the isolation of a fourth Drosophila T-box gene, optomotor-blind-related gene-1 (org-1), closely related to mouse and human TBX1. We localized TBX1 to chromosomal band 22q11, confirming a recent report, and discuss TBX1 as a candidate gene for DiGeorge and related syndromes.
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PMID:Isolation of a Drosophila T-box gene closely related to human TBX1. 961 Dec 67

Brachyury(T) is a mouse mutation, first described over 70 years ago, that causes defects in mesoderm formation. Recently several related genes, the T-box gene family, that encode a similar N-terminal DNA binding domain, the T-box, and that play critical roles in human embryonic development have been identified. It has been shown that human TBX5 and TBX3, if mutated, cause developmental disorders, Holt-Oram syndrome (OMIM 142900) and ulnar-mammary syndrome (OMIM 181450), respectively. We have identified four new human members of the T-box gene family, EOMES, TBX6, TBX18, and TBX19, and these genes have been mapped to different chromosomal regions by radiation hybrid mapping. The four T-box genes were classified into four different subfamilies and have also been subjected to phylogenomic analysis. Human EOMES maps at 3p21.3-p21.2. This Tbr1-subfamily gene is likely to play a significant role in early embryogenesis similar to that described for Xenopus eomesodermin. Human TBX6 maps at 16p12-q12. This Tbx6-subfamily gene is likely to participate in paraxial mesoderm formation and somitogenesis in human embryo. TBX18 is a novel member of the Tbx1 subfamily that maps at 6q14-q15. Two subgroups, TBX1/10 and TBX15/18 subgroups, could be distinguished within the Tbx1 subfamily. TBX19 is an orthologue of chick TbxT and maps at 1q23-q24. The genomic organization of TBX19 is highly similar to that of human T(Brachyury), another human member of the same subfamily.
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PMID:Identification, mapping, and phylogenomic analysis of four new human members of the T-box gene family: EOMES, TBX6, TBX18, and TBX19. 988 94

To better understand the role of TBX5, a T-box containing transcription factor in forelimb and heart development, we have studied the clinical features of Holt-Oram syndrome caused by 10 different TBX5 mutations. Defects predicted to create null alleles caused substantial abnormalities both in limb and heart. In contrast, missense mutations produced distinct phenotypes: Gly80Arg caused significant cardiac malformations but only minor skeletal abnormalities; and Arg237Gln and Arg237Trp caused extensive upper limb malformations but less significant cardiac abnormalities. Amino acids altered by missense mutations were located on the three-dimensional structure of a related T-box transcription factor, Xbra, bound to DNA. Residue 80 is highly conserved within T-box sequences that interact with the major groove of target DNA; residue 237 is located in the T-box domain that selectively binds to the minor groove of DNA. These structural data, taken together with the predominant cardiac or skeletal phenotype produced by each missense mutation, suggest that organ-specific gene activation by TBX5 is predicated on biophysical interactions with different target DNA sequences.
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PMID:Different TBX5 interactions in heart and limb defined by Holt-Oram syndrome mutations. 1007 12

To further define the role of a T-box transcription factor, Tbx5, in cardiac development, we have examined its expression in the developing mouse and chick heart and correlated this pattern with cardiac defects caused by human TBX5 mutations in Holt-Oram syndrome. Early in the developing heart, Tbx5 is uniformly expressed throughout the entire cardiac crescent. Upon formation of the linear heart tube, Tbx5 is expressed in a graded fashion, stronger near the posterior end and weaker at the anterior end. As the heart tube loops, asymmetric Tbx5 expression continues; Tbx5 is expressed in the presumptive left ventricle, but not the right ventricle or outflow tract. This pattern of expression is maintained in more mature hearts. Expression in the ventricular septum is restricted to the left side and is contiguous with left ventricular free wall expression. Trabeculae, vena cavae (inferior and superior), and the atrial aspect of the atrioventricular valves also express high levels of Tbx5. These patterns of Tbx5 expression provide an embryologic basis for the prevalence of atrial septal defects (ostium primum and secundum), ventricular muscular septal defects, and left-sided malformations (endocardial cushion defects, hypoplastic left heart, and aberrant trabeculation) observed in patients with Holt-Oram syndrome.
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PMID:Chamber-specific cardiac expression of Tbx5 and heart defects in Holt-Oram syndrome. 1037 8

Holt-Oram syndrome (HOS) is an autosomal dominant syndrome that comprises upper limb and cardiac defects. The gene responsible for HOS, TBX5, was isolated and many mutations have been identified in HOS patients. We analyzed 11 Chinese HOS patients (7 from three families and 4 sporadic cases) for TBX5 mutation by single strand conformation polymorphisms (SSCPs). Three SSCP changes were detected in two of the three familial cases and one sporadic case. Sequence analysis identified three novel, heterozygous mutations in TBX5: a frameshift mutation caused by one base deletion [C416del] in one family, a mis-sense mutation (Gln49Lys) induced by a base substitution (C145A) in another family, and the other mis-sense mutation (Ile54Thr) by T161C in one sporadic case. The patients with the frameshift mutations had severer clinical manifestations that involved aplasia/hypoplasia of the arm and thumbs, while those with the mis-sense mutations presented with milder anomalies such as absent or hypoplastic thumbs but without arm abnormalities. These observations may support a genotype-phenotype correlation in HOS patients with TBX5 mutation.
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PMID:Three novel TBX5 mutations in Chinese patients with Holt-Oram syndrome. 1084 87


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