ClinVar

Badens et al. (2002) described a 'new' mechanism leading to thalassemia intermedia (613985), a moderate form of thalassemia: a somatic deletion of the HBB gene in the hemopoietic lineage of a heterozygous beta-thalassemic patient. The deletion occurred on the chromosome 11 inherited from the mother, who had no abnormality of the HBB gene. The father had a beta-thalassemic trait due to the Mediterranean HBB nonsense mutation (141900.0312). The deletion gave rise to a mosaic of cells with either 1 or no functional beta-globin gene and it extended to a region of frequent loss of heterozygosity called LOH11A, which is located close to the HBB locus. Thus, loss of heterozygosity can be a cause of nonmalignant genetic disease.