DIGEORGE-SYNDROME AND RELATED SYNDROMES ASSOCIATED WITH 22Q11.2 DELETIONS - A REVIEW

DiGeorge syndrome (DGS) is a developmental defect which associates hyp o- or aplasia of the thymus and parathyroids, facial dysmorphism and c onotruncal cardiac malformations. The etiological factor in a great ma jority of DGS patients is monosomy for the 22q11.2 chromosomal region either through a large interstitial deletion of that region (inherited or de novo) or through an unbalanced translocation involving chromoso me 22. Ln one instance, a balanced translocation of chromosome 22 was associated with a DGS phenotype. Extensive analyses of this region of chromosome 22 has led to the obtention of precise physical maps of the corresponding genomic region, to the cloning of the balanced transloc ation breakpoint and to the isolation of different genes from the mini mal critical deleted region.