Is the inherited ACE genotype a trump or a joker?

Anaerobic endosymbiont generates energy for ciliate host by denitrification

Mitochondria are specialized eukaryotic organelles that have a dedicated function in oxygen respiration and energy production. They evolved about 2 billion years ago from a free-living bacterial ancestor (probably an alphaproteobacterium), in a process known as endosymbiosis1,2. Many unicellular eukaryotes have since adapted to life in anoxic habitats and their mitochondria have undergone further reductive evolution3. As a result, obligate anaerobic eukaryotes with mitochondrial remnants derive their energy mostly from fermentation4. Here we describe 'Candidatus Azoamicus ciliaticola', which is an obligate endosymbiont of an anaerobic ciliate and has a dedicated role in respiration and providing energy for its eukaryotic host. 'Candidatus A. ciliaticola' contains a highly reduced 0.29-Mb genome that encodes core genes for central information processing, the electron transport chain, a truncated tricarboxylic acid cycle, ATP generation and iron-sulfur cluster biosynthesis. The genome encodes a respiratory denitrification pathway instead of aerobic terminal oxidases, which enables its host to breathe nitrate instead of oxygen. 'Candidatus A. ciliaticola' and its ciliate host represent an example of a symbiosis that is based on the transfer of energy in the form of ATP, rather than nutrition. This discovery raises the possibility that eukaryotes with mitochondrial remnants may secondarily acquire energy-providing endosymbionts to complement or replace functions of their mitochondria.

Genetic Predisposition and Renal Allograft Failure

Renal allograft rejection or dysfunction often results in graft failure, and remains the major obstacle in the success of renal transplantation. Various immunological and nonimmunological factors are involved in allograft rejection. In addition to human leukocyte antigen loci, several genetically controlled molecules have been identified in recent years as playing important roles in the process of rejection. Genetic variants in genes encoding different T-helper (Th) type 1 and Th2 cytokines, chemokines and their receptors, growth factors, molecules of the renin-angiotensin system, enzymes of the homocysteine pathway, and proteins acting as substrates of immunosuppressive drugs impact on the success of engraftment and highlight the concept of genetic predisposition to allograft rejection. This review evaluates specific genetic variants and their functional roles in graft failure, with an emphasis on the latest methodologies available for genotyping, and appropriate strategies to enable them to become a tool of predictive and individualized medicine to ensure better transplant outcome.

High prevalence of ACE DD genotype among north Indian end stage renal disease patients

BACKGROUND

The Renin-Angiotensin system (RAS) is a key regulator of both blood pressure and kidney functions and their interaction. In such a situation, genetic variability in the genes of different components of RAS is likely to contribute for its heterogeneous association in the renal disease patients. Angiotensin converting enzyme-1 (ACE-1) is an important component of RAS which determines the vasoactive peptide Angiotensin-II.

METHODS

In the present study, we have investigated 127 ESRD patients and 150 normal healthy controls from north India to deduce the association between ACE gene polymorphism and ESRD. The inclusion criteria for patients included a constantly elevated serum creatinine level above normal range (ranging from 3.4 to 15.8) and further the patients were recommended for renal transplantation. A total of 150 normal healthy controls were also genotyped for ACE I/D polymorphism. The criterion of defining control sample as normal was totally based on the absence of any kidney disease determined from the serum creatinin level. Genotyping of ACE I/D were assayed by polymerase chain reaction (PCR) based DNA amplification using specific flanking primers Based on the method described elsewhere.

RESULTS

The difference of DD and II genotypes was found highly significant among the two groups (p = 0.025; OR = 3.524; 95% CI = 1.54-8.07). The combined genotype DD v/s ID+II comparison validated that DD genotype is a high risk genotype for ESRD (p = 0.001; OR = 5.74; 95% CI limit = 3.4-8.5). However, no correlation was obtained for different biochemical parameters of lipid profile and renal function among DD and non DD genotype. Interestingly, approximately 87% of the DD ESRD patients were found hypertensive in comparison to the 65% patients of non DD genotype

CONCLUSION

Based on these observations we conclude that ACE DD genotype implicate a strong possible role in the hypertensive state and in renal damage among north Indians. The study will help in predetermining the timing, type and doses of anti-hypertensive therapy for ESRD patients.

Insertion/deletion polymorphism in the angiotensin-converting enzyme gene and risk of and prognosis after myocardial infarction

OBJECTIVES

We sought to prospectively investigate whether genetic variation at the angiotensin-converting enzyme gene locus defined by an insertion (I)/deletion (D) polymorphism influences the risk of myocardial infarction or prognosis after infarction, or both.

BACKGROUND

It has been suggested that the deletion allele of the angiotensin-converting enzyme gene, and specifically the DD genotype, may increase the risk of myocardial infarction, although previous studies have produced conflicting reports. No studies have yet examined the effect of I/D polymorphism on survival after infarction.

METHODS

Angiotensin-converting enzyme genotypes in 684 patients with myocardial infarction recruited at the time of the acute event through coronary care units in two centers were compared with those of 537 control subjects recruited from the base populations. All patients were followed up to assess the impact of the angiotensin-converting enzyme genotype on prognosis.

RESULTS

We found no difference (p = 0.89) in the genotype distribution between patients and control subjects (patients DD 31%, ID 47%, II 22%; control subjects DD 30%, ID 48%, II 22%). The odds ratio for myocardial infarction for DD compared with II/ID genotype adjusted for age, gender and center was 1.16 (95% confidence interval [CI] 0.82 to 1.65, p = 0.44). The study had 90% power to detect a 1.5-fold increase in risk of myocardial infarction associated with the DD genotype. For one center, data were available for other risk factors (hypertension, diabetes, angina, previous myocardial infarction, smoking, body mass index, total and high density lipoprotein cholesterol) in both patients and control subjects. In a stepwise logistic regression analysis the odds ratio for DD versus ID/II genotypes remained nonsignificant (1.44, 95% CI 0.84 to 2.46, p = 0.20) for these subjects. Over a median follow-up period of 15 months (range 3 to 22), 155 patients (22.7%) died. There was no difference in mortality between subjects with the DD genotype and those with ID/II genotypes. (21.8% vs. 23.1%, p = 0.25). Likewise, there was no difference in the distribution of survival times in the two groups (p = 0.62). The study had 70% power to detect a 1.5-fold increase in mortality during follow-up associated with the DD genotype.

CONCLUSIONS

We conclude that in the groups studied, genetic variation at the angiotensin-converting enzyme gene locus defined by I/D polymorphism does not significantly influence either the risk of or the short- to medium-term prognosis after myocardial infarction.