Thalassaemia mutations within the 5'UTR of the human beta-globin gene disrupt transcription.

The mechanisms by which mutations within the 5' untranslated region (UTR) of the human beta-globin gene (HBB) cause thalassaemia are currently not well understood. We present here the first comprehensive comparative functional analysis of four 'silent' mutations in the human beta-globin 5'UTR, namely: +10(-T), +22(G --> A), +33(C --> G) and +(40-43)(-AAAC), which are present in patients with beta-thalassaemia intermedia. Expression of these genes under the control of the beta-globin locus control region in stable transfected murine erythroleukaemia cells showed that all four mutations decreased steady state levels of mRNA to 61.

Lack of Fas (APO-1/CD95) gene structural alterations or transcript variant ratio changes in breast cancer.

Fas (APO-1/CD95) is a transmembrane receptor protein involved in cell death signaling. Fas receptor and ligand are both expressed in breast cancer cells, however these cells are resistant to apoptosis. Fas gene mutations were detected in hematological and solid tumors, while overexpression of a soluble Fas isoform in serum was related to cancer stage and prognosis.

The beta-globin C-->G mutation at 6 bp 3' to the termination codon causes beta-thalassaemia by decreasing the mRNA level.

We have studied the expression of the silent beta-thalassaemia term+6 (C-->G) mutation, at nucleotide 6 after the stop codon within the human beta-globin 3' untranslated regions (3'UTR), by stable transfection in murine erythroleukaemia (MEL) cells. Steady state mRNA levels from transfected MEL cells containing the term+6 mutant allele were reduced by 52-60%, compared with those obtained from the normal beta-globin gene, in both total and cytoplasmic RNA fractions, showing that the mutation itself is responsible for the similar data obtained from patients. Upon analysis of nuclear RNA, the term+6 mutation was found to also lower the ratio of cleaved/uncleaved transcripts by 22-30%, thus revealing that it interferes with correct 3'-end formation of beta-globin mRNA.