Introduction: α-thalassaemia is the most common hereditary anaemia in the world. The majority of Danish immigrants come from countries, where the prevalence of αthalassaemia is high. The aim of this study was to evaluate its frequency in Danish immigrants. Material and methods: Over a year, all samples sent for haemoglobin analysis to our institution from patients with an MCV value ≤80 fl were examined for an α-thalassaemia haplotype by a PCR-based method. All samples were measured, irrespective of the MCV value, over a period of 3 months. Results: We received 239 samples with an MCV m80 fl. Fifty-seven individuals (23.8%) had one or two α-thalassaemia haplotypes. In comparison, a β-thalassaemia trait was found in 44 individuals (18.4%). The -(α3.7 haplotype was the most common (91%). Most were heterozygous, but homozygous cases and combinations with an α0-deletion or a haemoglobin variant were also found. The more serious α0-haplotype was found in nine cases (15.8%), among whom four cases had haemoglobin H disease. In 141 patients with MCV values above 80 fl, 11 patients had an α+-deletion. From these findings and with the knowledge of the prevalence of β-thalassaemia in immigrants in Denmark, we assessed the prevalence of α-thalassaemia to be between 3 and 8%. Conclusions: α-thalassemia is no longer a rare, differential diagnosis in Denmark. A national strategy is indicated for prophylactic measures, including screening for the serious α0-deletion and prenatal diagnosis in accordance with international recommendations.

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differential diagnosis immigrant Diagnosis, Differential gene deletion human Denmark controlled study measurement mean corpuscular volume haplotype Humans anemia Heterozygote Detection genetic screening Prenatal Diagnosis risk factor high risk population polymerase chain reaction prevalence Article prophylaxis major clinical study hemoglobin H heterozygosity hemoglobin analysis beta thalassemia homozygosity alpha-Thalassemia hemoglobin variant Haplotypes hemoglobin alpha thalassemia Emigration and Immigration prenatal screening disease severity disease association genetic disorder practice guideline