Molecular characterization of the PK-LR gene in sixteen pyruvate kinase-deficient patients.

We studied the PK-LR gene in 16 unrelated patients with congenital haemolytic anaemia associated with erythrocyte pyruvate kinase deficiency. Fifteen different mutations were detected among the 28 mutated alleles identified: two deletions (del 1010G, del 1042--1044); one four nucleotide duplication (nt 1515--1518, GGTC); one splice site [IVS6(-2)t]; nine missense (991A, 1003A, 1151T, 1160G, 1181T, 1181A, 1456T, 1483A, 1529A); and two nonsense (721T, 1675T) mutations. Eight of them [del 1010G, del 1042--1044, dupl 1515--1518, IVS6(-2)t, 1003A, 1160G, 1181T, 1181A] were novel. The deletion 1042-1044 causes the loss of Lys 348. Deletion 1010G and duplication 1515-1518 determine a frameshift and the creation of a stop codon at nucleotides 1019 and 1554 respectively. Mutation IVS6(-2)t leads to an alteration of the 5' and 3' splice site consensus sequence; the cDNA analysis shows a 67-bp deletion in the first part of exon 11 (del 1437--1503). All the four new missense mutations involve highly conserved amino acids. The most frequent mutation in Italy would appear to be 1456T. Correlation was made between mutations, biochemical characteristics of the enzyme and clinical course of the disease.