ISOLATION OF A DROSOPHILA T-BOX-GENE CLOSELY-RELATED TO HUMAN TBX1

T-box genes, in all metazoans studied from nematode to man, exist in s mall gene families. They encode transcription factors with a novel, la rge, and highly conserved DNA binding domain termed the T-domain. In a ll cases studied, T-box genes have important developmental roles. Two familial diseases, Holt-Gram syndrome and ulnar-mammary syndrome, were recently shown to be caused by mutations in the human T-box genes TBX 5 and TBX3, respectively. T-box genes were first identified in Drosoph ila and mouse. Two of the three known Drosophila T-box genes show a cl ose sequence homology to mammalian genes. Similarities in the phenotyp es of fly and mammalian mutants can be taken as evidence of functional conservation. We report here the isolation of a fourth Drosophila T-b ox gene, optomotor-blind-related gene-1 (org-1), closely related to mo use and human TBX1. We localized TBX1 to chromosomal band 22q11, confi rming a recent report, and discuss TBX1 as a candidate gene for DiGeor ge and related syndromes. (C) 1998 Elsevier Science B.V. All rights re served.