[Three new mutations in the porphobilinogen deaminase gene, detected in acute intermittent porphyria patients from Russia].
Porphobilinogen deaminase (PBGD) is a key enzyme of the heme biosynthetic pathway. Defects in the PBGD gene lead to an autosomal dominant disease, acute intermittent porphyria (AIP). Almost all AIP patients with rare exceptions are heterozygous for the defective gene. To date, at least 160 different mutations causing AIP are identified. Extensive investigations along this line are conducted in many countries of the world. In Russia these studies had not been hitherto performed. Here we report the results of molecular genetic examination of four Russian patients with AIP diagnosed from clinical symptoms. By direct sequencing of the PBGD gene or the corresponding cDNA, we have detected four mutations, three of which were not previously encountered in the world population. These are TAAG deletion in intron 7 between positions +2 and (IVS7 2-5 delTAAG); T deletion in the initiation codon ATG of exon 3, and the G for C replacement at position -1 of intron 5 (IVS5 as -1 G:C), which disrupts splicing. In addition, in one female patient, a known deletion CT in codon 68 was revealed. In two patients, expression of PBGD gene alleles was significantly disproportional, so that normal mRNA prevailed in one case and mRNA of nonerythroid type in the other. Deletion in intron 7 was easily detectable due to the formation of a heteroduplex fragment with abnormal electrophoretic mobility directly in PCR. This simple heteroduplex analysis allowed us to exclude AIP carriage in son and daughter of a female patient with the genetic defect.
Surin
V L
VL
Hematological Research Center of Medicine, Russian Academy of Medical Science, Moscow, 125167 Russia.
Luk'ianenko
A V
AV
Karpova
I V
IV
Misiurin
A V
AV
Pustovot
Ia S
IaS
Pivnik
A V
AV
D001483:Base Sequence; D003062:Codon; D017931:DNA Primers; D005091:Exons; D006579:Heterozygote; D011163:Hydroxymethylbilane Synthase / Q000235:genetics*; D007438:Introns; D009154:Mutation; D017118:Porphyria, Acute Intermittent / Q000201:enzymology / Q000235:genetics*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D012426:Russia; D017384:Sequence Deletion
D003062:Codon; D017931:DNA Primers; D012333:RNA, Messenger; D011163:Hydroxymethylbilane Synthase