Disease relevance of HBQ1

• Furthermore, by primer extension of single-stranded oligonucleotide probes, we show that the theta 1-globin gene of humans is transcribed in an erythroleukemia cell line K562 [1].

High impact information on HBQ1

• Here we present the complete DNA sequence of a cloned theta 1-globin gene of humans, and show that it contains no apparent defects that would abolish its expression [1].
• Our results provide strong evidence that the theta 1-globin gene of humans is transcriptionally active in cells of erythroid origin, and suggests the presence of a functional theta 1-polypeptide in specific cells, possibly those of early erythroid tissue [1].
• Both theta 1-globin genes are split into three exons with the potential to code for a polypeptide of length 141 amino acids [1].
• The putative polypeptide is 141 amino acids long, identical to that of the alpha- or zeta-globin, but its predicted amino-acid sequence is nearly as different from the orang-utan alpha-globin (55 differences) as the human zeta-globin is from the human alpha-globin (59 differences), suggesting an ancient history for the theta 1-globin gene [2].
• The conservation of this novel arrangement among the higher primates suggests that an inserted Alu family repeat and its flanking genomic sequence have co-evolved, for at least 30 million years, to provide the canonical CCAAT and TATA promoter elements of the theta 1 globin genes in higher primates [3].

Biological context of HBQ1

• The recently identified theta-globin gene subfamily consists of the theta 1-globin gene located downstream from the alpha 1-globin gene, and several other members including at least one truncated, processed pseudogene psi theta 2 (refs 1,6) [1].
• Zeta and theta 1-globin gene deletions located on the same chromosome [4].
• A new deletion of approximately 8.5 kb that includes the alpha 2-, alpha 1-, and theta 1-globin genes was detected in a father and newborn son of a black family from Georgia. In the newborn baby the chromosome with the deletion occurred together with a rightward (-alpha 3.7) deletion chromosome [5].
• Like K562 cells, HEL cells also displayed hemin-inducible theta 1-globin gene expression [6].
• Following transfer of human chromosome 16 from embryonic/fetal K562 to the adult MEL cells, theta 1-globin gene remained active but lost its potential for inducibility, suggesting probably a trans regulation mechanism [6].

Anatomical context of HBQ1

• Developmental and inducible patterns of human theta 1-globin gene expression in embryonic/fetal and adult erythroid cells [6].

Other interactions of HBQ1

• We have detected a novel alpha-thalassemia-2 with a large (18+ kb) deletion involving the alpha 1- and theta 1-globin genes and the 3' hypervariable region sequence [7].

References