An inherited hypochromic microcytic anemia transmitted in an autosomal manner has been observed in three generations of an English family. Affected members had the hallmarks of heterozygous beta-thalassemia, ie, elevated levels of hemoglobin A2 and imbalanced globin chain synthesis. However, despite extensive sequence analysis, no mutations could be found in or around the beta-globin genes of either the propositus or two other affected members from two different generations. Linkage analysis using restriction fragment length polymorphisms in the beta-globin gene cluster clearly showed that the gene responsible for the beta-thalassemia phenotype segregates independently of the beta-gene complex. Therefore, this condition represents a novel form of the disease.

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