A new PKLR gene mutation in the R-type promoter region affects the gene transcription causing pyruvate kinase deficiency.
Mutations in the PKLR gene responsible for pyruvate kinase (PK)-deficient anaemia are mainly located in the coding regions: 11 are in the splicing sites and, recently, three mutations have been described in the promoter region. We now report a novel point mutation A-->G on nucleotide 72, upstream from the initiation codon of the PKLR gene, in four Portuguese PK-deficient patients. This new regulatory mutation occurs within the most proximal of the four GATA motifs (GATA-A element) in the R-type promoter region. In two patients who were homozygous for this mutation, a semiquantitative reverse transcription polymerase chain reaction (PCR) procedure was used to evaluate the amount of R-PK mRNA transcript in the reticulocytes. The mRNA level was about five times lower than in normal controls, demonstrating that the PKLR gene transcription is severely affected, most probably because the -72A-->G point mutation disables the binding of the erythroid transcription factor GATA-1 to the GATA-A element. Supporting these data, the two patients homozygous for the -72A-->G mutation had severe haemolytic anaemia and were transfusion dependent until splenectomy. Two other patients who were compound heterozygous for this mutation and the previously described missense mutation 1456C-->T had a mild condition.
Manco
L
L
Unidade de Hematologia Molecular, Centro Hospitalar de Coimbra, Portugal. lmanco@ci.uc.pt
Ribeiro
M L
ML
Máximo
V
V
Almeida
H
H
Costa
A
A
Freitas
O
O
Barbot
J
J
Abade
A
A
Tamagnini
G
G
D000746:Anemia, Hemolytic, Congenital Nonspherocytic / Q000201:enzymology / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D004912:Erythrocytes / Q000201:enzymology; D050981:Erythroid-Specific DNA-Binding Factors; D005260:Female; D050982:GATA1 Transcription Factor; D006720:Homozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017354:Point Mutation; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011770:Pyruvate Kinase / Q000172:deficiency* / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics
D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; D012333:RNA, Messenger; D014157:Transcription Factors; D011770:Pyruvate Kinase