Mutations in the hydroxymethylbilane synthase (HMBS) gene are responsible for the inherited disorder of acute intermittent porphyria (AIP). AIP is diagnosed on the basis of characteristic clinical symptoms, elevated levels of urinary porphyrin precursors aminolevulinic acid (ALA) and porphobilinogen (PBG) and a decreased erythrocytic HMBS activity, although an identifiable HMBS mutation provides the ultimate proof for AIP. Six Israeli AIP families underwent biochemical and mutation analysis in order to establish an AIP diagnosis. Variability with respect to the ALA/PBG levels and HBMS activity was found among the index patients. Indeed, each family carried a unique mutation in the HMBS gene. A novel missense c.95G>C (p.R32P) was shown to be a de novo mutation in one family, along with five known mutations p.T59I, p.D178N, p.V215M, c.730_731delCT and c.982_983delCA identified in the rest of the families. Both R32P and D178N were expressed in a prokaryotic system. Recombinant p.R32P was enzymatically inactive as demonstrated by a <1% residual activity, whereas p.D178N possessed 81% of the activity of the wild type enzyme. However, the p.D178N mutant did display a shift in optimal pH and was thermo labile compared to the wild type. Among the four missense mutations, p.R32P and p.V215M had not only harmful effects on the enzyme in vitro but also were associated with high levels of ALA/PBG in patients. On the other hand, the in vitro effect of both p.T59I and p.D178N, and the impact of these mutations on the enzyme structure and function as interpreted by the 3-D structure of the Escherichia coli enzyme, were weaker than that of p.R32P and p.V215M. Concomitantly, patients carrying the p.T59I or p.D178N had normal or borderline increases in ALA/PBG concentrations although they presented characteristic clinical symptoms. These findings provided further insights into the causal relationship between HMBS mutations and AIP.

• MeSH
• akutní intermitentní porfyrie etnologie   genetika   MeSH
• bodová mutace MeSH
• dospělí MeSH
• exony genetika   MeSH
• financování organizované MeSH
• hydroxymethylbilansynthasa genetika   chemie   MeSH
• konformace proteinů MeSH
• kyselina aminolevulová moč   MeSH
• lidé středního věku MeSH
• lidé MeSH
• missense mutace MeSH
• mladiství MeSH
• mladý dospělý MeSH
• molekulární modely MeSH
• mutační analýza DNA MeSH
• porfobilinogen metabolismus   MeSH
• proteiny z Escherichia coli chemie   MeSH
• sekvenční delece MeSH
• senioři nad 80 let MeSH
• stabilita proteinů MeSH
• substituce aminokyselin MeSH
• vztahy mezi strukturou a aktivitou MeSH
• židé genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• ženské pohlaví MeSH
• Geografické názvy
• Evropa MeSH
• Indie MeSH
• Izrael MeSH

The porphyrias are group of mostly inherited disorders in which a specific spectrum of accumulated and excreted porphyrins and heme precursors are associated with characteristic clinical features. There are eight enzymes involved in the heme synthesis and defects in seven of them cause porphyria. Four of them are described as acute hepatic porphyrias, which share possible precipitation of acute attacks with symptoms engaging the nervous system. Acute intermittent porphyria (AIP), caused by partial deficiency of the porphobilinogen deaminase (PBGD), is the most frequent among hepatic porphyrias. Clinical expression is highly variable and ~ 90 % of AIP heterozygotes remain asymptomatic throughout life. During systematic genetic analysis of the AIP patients diagnosed in the Czech and Slovak Republics, we found a special case of AIP. In a 15-year-old boy with abdominal and subsequent neurological symptomatology, we identified de novo mutation 966insA within the PBGD gene leading to a stop codon after 36 completely different amino acids compared to the wt-sequence. To establish the effects of this mutation on the protein structure, we expressed mutant constructs with described mutation in E. coli and analyzed their biochemical and enzymatic properties. Moreover, computer-assisted protein structure prediction was performed.

• MeSH
• akutní intermitentní porfyrie diagnóza   enzymologie   genetika   MeSH
• běloši MeSH
• Escherichia coli metabolismus   MeSH
• hydroxymethylbilansynthasa chemie   genetika   izolace a purifikace   MeSH
• lidé MeSH
• mladiství MeSH
• molekulární modely MeSH
• molekulární sekvence - údaje MeSH
• mutace * MeSH
• mutační analýza DNA MeSH
• rodokmen MeSH
• sekvence nukleotidů MeSH
• Check Tag
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH