Cytogenetic and Molecular Investigations in Chromosomal Instability Syndromes

In a number of genetic disorders with an autosomal recessive mode of inheritance, increased spontaneous and/or induced chromosomal instability has been found. The knowledge of the underlying gene mutations and their consequences for the cellular repair processes will undoubtedly broaden our understanding of this vital cellular function. The classical chromosomal instability syndromes are Bloom’s syndrome (BS), Fanconi’s anaemia (FA) and ataxia telangiectasia (AT), all of which express specific cytogenetic peculiarities. The diagnosis of these syndromes is still generally based on cytogenetic analyses. This is due, firstly, to our inability to reliably identify all patients on the basis of clinical examination alone and, secondly, to the lack of appropriate molecular probes.