Sequence polymorphisms of potential functional relevance in the beta-globin gene locus

The purpose of this review is to give a general up-date of the most recent developments concerning polymorphisms within the beta-globin gene cluster. The first polymorphisms to be identified were mostly restriction fragment length polymorphisms. They were important markers both for their use as diagnostic tools and for anthropological investigations. Although they have been associated with specific patterns of globin gene expression in the hemoglobinopathies, none have been demonstrated to have any intrinsic functional significance. More recently, additional single nucleotide variations and microsatellite-like polymorphic simple sequence repeats have been identified which are frequently located in trans-acting protein binding segments and hence might affect regulatory processes.