Genetic polymorphism of ACE and the angiotensin II type1 receptor genes in children with chronic kidney disease

AIM AND METHODS

We investigated the association between polymorphisms of the angiotensin converting enzyme-1 (ACE-1) and angiotensin II type one receptor (AT1RA1166C) genes and the causation of renal disease in 76 advanced chronic kidney disease (CKD) pediatric patients undergoing maintenance hemodialysis (MHD) or conservative treatment (CT). Serum ACE activity and creatine kinase-MB fraction (CK-MB) were measured in all groups. Left ventricular mass index (LVMI) was calculated according to echocardiographic measurements. Seventy healthy controls were also genotyped.

RESULTS

The differences of D allele and DI genotype of ACE were found significant between MHD group and the controls (p = 0.0001). ACE-activity and LVMI were higher in MHD, while CK-MB was higher in CT patients than in all other groups. The combined genotype DD v/s ID+II comparison validated that DD genotype was a high risk genotype for hypertension .~89% of the DD CKD patients were found hypertensive in comparison to ~ 61% of patients of non DD genotype(p = 0.02). The MHD group showed an increased frequency of the C allele and CC genotype of the AT1RA1166C polymorphism (P = 0.0001). On multiple linear regression analysis, C-allele was independently associated with hypertension (P = 0.04).

CONCLUSION

ACE DD and AT1R A/C genotypes implicated possible roles in the hypertensive state and in renal damage among children with ESRD. This result might be useful in planning therapeutic strategies for individual patients.

A century of B chromosomes in plants: so what?

BACKGROUND

Supernumerary B chromosomes (Bs) are a major source of intraspecific variation in nuclear DNA amounts in numerous species of plants. They favour large genomes, and create polymorphisms for DNA variation in natural populations. By studying Bs we can gain useful knowledge about the organization, function and evolution of genomes. There are also significant biological questions concerning the origin and structural organization of Bs, and the way in which these selfish elements can establish themselves by exploiting the replicative machinery of their host genome nucleus.

SCOPE

It is a sine qua non that Bs originate from the A chromosomes, in a variety of ways. We can study their modes of drive and ask how it is that chromosomes which apparently lack genes can have control over their own drive process which leads to their survival in natural populations. Molecular cytogenetic studies are opening up new avenues of investigation. Population equilibria for B frequencies are determined by a balance between accumulation and harmful effects. Bs are also subject to meiotic loss due to polysomy and to elimination at meiosis as univalents. These balancing forces can be seen in the context of host/parasite interaction, based on a dissection of the genetic elements in both As and Bs (in maize) which interact to bring about a stable equilibrium, at least for a snapshot in time.

CONCLUSIONS

Aside from their intrinsic enigmatic properties, B chromosomes make useful experimental tools to study genome organization. Thus far they have not been exploited for their applications, other than through the use of A-B translocations used for gene mapping in maize; but there are opportunities to use them to modulate the frequency and distribution of recombination, to diploidize allopolyploids, to study centromeres and to be developed as plant artificial chromosomes; given that they can be structurally modified and their inheritance stabilized.

Genetic variants in the enhancer region of the thymidylate synthase gene in the Chilean population

AIMS

Thymidylate synthase (TYMS) is an important target enzyme for the fluoropyrimidines. The TYMS gene enhancer region possesses tandemly repeated (TSER) sequences that are polymorphic in humans and different among ethnic groups. The aims of this study were to estimate the frequencies of the TSER variants in two hospital samples located in the northern (HSJ) and eastern (CLC) parts of Santiago, Chile, and compare them with the frequencies in other populations of different ethnic origin.

METHODS

Genotyping of TSER variants in 368 Chilean subjects (HSJ = 178 and CLC = 190) by polymerase chain reaction; products of amplification were electrophoresed, obtaining fragments of 250 bp for allele TSER*3 and 220 bp for allele TSER*2.

RESULTS

The two hospital samples had different degrees of Amerindian admixture (HSJ 34.5%; CLC 15.9%), which was not reflected in the observed frequencies of the CLC TSER*3: 56.8% and HSJ TSER*3: 53.4%.

CONCLUSIONS

Our results are unexpected, considering that genetic markers in the Chilean population generally show allele frequencies between those observed in European Caucasians and Amerindians and that the percentage of Amerindian admixture in CLC is lower than in HSJ. Both hospitals should have had greater frequencies of TSER*3 than were found and the frequency should have been greater in HSJ than in CLC; the only logical explanation of our results is that the frequency of this allele in aboriginal Chilean people is much lower than the 80% estimated for Mongoloid populations.

Apo B gene haplotype is associated with lipid profile of higher risk for coronary heart disease in Caucasian Brazilian men

We investigated using haplotype analysis whether genetic variation of the apo B gene is associated with a higher risk for coronary heart disease in a Brazilian population. Ins/Del, XbaI, and EcoRI polymorphic sites of the apolipoprotein B (apo B) gene were studied in 67 patients with CHD and in 67 age-matched healthy individuals selected from a population of Brazilians. The allelic frequency of apo B polymorphisms did not differ between the CHD patients and controls. However, a significant linkage disequilibrium was observed between the XbaI site and Ins/Del polymorphism of the apo B gene in CHD individuals (chi2, P < 0.01). The simultaneous presence of the rare X+ and Del alleles (X+Del haplotype) in males of CHD group was associated with significantly higher serum levels of total cholesterol (P < 0.01), triglycerides (P < 0.05), and LDL-cholesterol (P < 0.05), and with a higher TC/HDL-C ratio (P < 0.05). These data indicate that a single haplotype, X+Del, within the apo B gene exerts an impact on lipid metabolism and may contribute to the susceptibility to development of CHD in males from a population of Brazilians.