New Challenges in Diagnosis of Haemoglobinopathies: Migration of Populations

The current influx of economic migrants and asylum seekers from countries with a high prevalence of haemoglobinopathies creates new challenges for health care systems and diagnostic laboratories. The migration of carriers introduces new and novel haemoglobinopathy mutations to the diagnostic repertoire of a laboratory, often creating new pressures to improve and update the carrier screening technology and diagnostic scope. For antenatal screening programmes, the marriage of partners from different ethnic groups can lead to the risk of compound heterozygote children being born novel mutation combinations, creating problems in the provision of accurate advice regarding the expected phenotype of the thalassaemia or haemoglobinopathy disorder. In the UK, the impact of immigration required the National Haemoglobinopathy Reference laboratory to change the strategy and techniques used for the molecular diagnosis of thalassaemia and the haemoglobinopathies. In 2005, due to the increasingly large range of β-thalassaemia mutations that needed to be diagnosed, the laboratory switched from a three-step screening procedure using ARMS-PCR to a simpler but more expensive one-step strategy of DNA sequencing of the beta and alpha globin genes for all referrals. After ten years of employing this strategy, a further 57 novel thalassaemia and haemoglobionpopthy alleles were discovered (11 new β-chain variants, 15 α-chain variants, 19 β-thalassaemia mutations and 12 α⁺-thalassaemia mutations), increasing further the extremely heterogeneous spectrum of globin gene mutations in the UK population.