Diagnosis of the haemoglobinopathies.
Despite having been extensively studied at both the biochemical, haematological and molecular levels, the haemoglobinopathies continue to provide a diagnostic challenge particularly in the multiethnic communities seen in Australia. Early detection and characterisation of the haemoglobinopathies is essential so that appropriate counselling can be provided to couples and families who may be at risk of severe haematological consequences. Although DNA diagnostics have made a major impact on our understanding and detection of the haemoglobinopathies, DNA mutation testing should never be considered a short cut or the test of first choice in the workup of a haemoglobinopathy. A careful three tier approach involving: (1) Full blood count (2) Special haematological tests, followed by (3) DNA mutation analysis, provides the most effective way in which to detect primary gene mutations as well as gene-gene interactions that can influence the overall phenotype. Just as important as the laboratory investigations is the family work up. Often, the first and most helpful clue to gene gene interactions comes from the family study. In Australia, there are many different forms of alpha and beta thalassaemia. Increasingly, different Hb Variants are being detected, and their effects per se, or in combination with the thalassaemias, provide additional diagnostic challenges.
Trent
Ronald J A
RJ
Department of Molecular & Clinical Genetics, Royal Prince Alfred Hospital, Camperdown, NSW, Australia. rtrent@med.usyd.edu.au