Homozygous deletional alpha + thalassaemia associated with unequal expression of the two remaining alpha 1 genes (alpha 1A and alpha 1Q).
A Cambodian family presenting several haemoglobinopathies, Hb E, Hb Q and alpha + thalassaemia, has been investigated. DNA analysis showed that the thalassaemia syndrome corresponds to a leftward type (4.2 kb) deletional form of alpha + thalassaemia. Genotypes found in the family are: propositus -alpha A/-alpha Q, beta A/beta E., mother and older sister alpha A alpha A/-alpha Q, beta A/beta E., father alpha A alpha A/-alpha A, beta A/beta A. The propositus consistently presents an alpha Q/alpha A chain ratio of 60/40 although both chains are products of alpha 1 loci. The relatively higher expression of the alpha Q chain is not observed in the mother and therefore makes it unlikely to reflect anything other than differential expression of the maternal -alpha Q/ and paternal -alpha A/ haplotypes. This observation raises the possibility that both haplotypes are not strictly identical and that the region of the cross-over event is important for alpha gene expression.
D002872:Chromosome Deletion; D004247:DNA / Q000097:blood; D004588:Electrophoresis, Cellulose Acetate; D005260:Female; D005786:Gene Expression Regulation; D005796:Genes; D006455:Hemoglobins, Abnormal / Q000032:analysis; D006720:Homozygote; D006801:Humans; D007231:Infant, Newborn; D007525:Isoelectric Focusing; D008297:Male; D010375:Pedigree; D013789:Thalassemia / Q000097:blood / Q000235:genetics*
D006455:Hemoglobins, Abnormal; D004247:DNA