ABSTRACT
The SERPINA1 gene is highly polymorphic, with more than 100 variants described in databases. SERPINA1 encodes the alpha-1 antitrypsin (AAT) protein, and severe deficiency of AAT is a major contributor to pulmonary emphysema and liver diseases. In Spanish patients with AAT deficiency, we identified seven new variants of the SERPINA1 gene involving amino acid substitutions in different exons: PiSDonosti (S+Ser14Phe), PiTijarafe (Ile50Asn), PiSevilla (Ala58Asp), PiCadiz (Glu151Lys), PiTarragona (Phe227Cys), PiPuerto Real (Thr249Ala), and PiValencia (Lys328Glu). We examined the characteristics of these variants and the putative association with the disease. Mutant proteins were overexpressed in HEK293T cells, and AAT expression, polymerization, degradation, and secretion, as well as antielastase activity, were analyzed by periodic acid-Schiff staining, Western blotting, pulse-chase, and elastase inhibition assays. When overexpressed, S+S14F, I50N, A58D, F227C, and T249A variants formed intracellular polymers and did not secrete AAT protein. Both the E151K and K328E variants secreted AAT protein and did not form polymers, although K328E showed intracellular retention and reduced antielastase activity. We conclude that deficient variants may be more frequent than previously thought and that their discovery is possible only by the complete sequencing of the gene and subsequent functional characterization. Better knowledge of SERPINA1 variants would improve diagnosis and management of individuals with AAT deficiency.
Subject(s)
alpha 1-Antitrypsin Deficiency/genetics , alpha 1-Antitrypsin/genetics , alpha 1-Antitrypsin/metabolism , Adult , Aged , Female , Gene Frequency , HEK293 Cells , Humans , Male , Middle Aged , Mutant Proteins/chemistry , Mutant Proteins/genetics , Mutant Proteins/metabolism , Mutation, Missense , Protein Stability , Proteolysis , alpha 1-Antitrypsin/chemistryABSTRACT
BACKGROUND: The emergence of drug resistance in Plasmodium falciparum has been a major contributor to the global burden of malaria. Drug resistance complicates treatment, and it is one of the most important problems in malaria control. This study assessed the level of mutations in P. falciparum genes, pfdhfr, pfdhps, pfmdr1, and pfcrt, related to resistance to different anti-malarial drugs, in the Continental Region of Equatorial Guinea, after 8 years of implementing artesunate combination therapies as the first-line treatment. RESULTS: A triple mutant of pfdhfr (51I/59R/108N), which conferred resistance to sulfadoxine/pyrimethamine (SP), was found in 78% of samples from rural settings; its frequency was significantly different between urban and rural settings (p = 0.007). The 164L mutation was detected for the first time in this area, in rural settings (1.4%). We also identified three classes of previously described mutants and their frequencies: the partially resistant (pfdhfr 51I/59R/108N + pfdhps 437G), found at 54% (95% CI 47.75-60.25); the fully resistant (pfdhfr 51I/59R/108N + pfdhps 437G/540E), found at 28% (95% CI 7.07-14.93); and the super resistant (pfdhfr 51I/59R/108N + pfdhps 437G/540E/581G), found at 6% (95% CI 0.48-4.32). A double mutation in pfmdr1 (86Y + 1246Y) was detected at 2% (95% CI 0.24-3.76) frequency, distributed in both urban and rural samples. A combination of single mutations in the pfmdr1 and pfcrt genes (86Y + 76T), which was related to resistance to chloroquine and amodiaquine, was detected in 22% (95% CI 16.8-27.2) of samples from the area. CONCLUSIONS: The high level of mutations detected in P. falciparum genes related to SP resistance could be linked to the unsuccessful withdrawal of SP treatment in this area. Drug resistance can reduce the efficacy of intermittent prophylactic treatment with SP for children under 5 years old and for pregnant women. Although a high number of mutations was detected, the efficacy of the first-line treatment, artemisinin/amodiaquine, was not affected. To avoid increases in the numbers, occurrence, and spread of mutations, and to protect the population, the Ministry of Health should ensure that health centres and hospitals are supplied with appropriate first-line treatments for malaria.