Homozygosity or mixed heterozygosity for mutations in the adenine phosphoribosyltransferase gene cause enzyme deficiency directing adenine through an alternative metabolic pathway. This results in the production of 2,8-dihydroxyadenine, which is actively secreted into the urine. 2,8-dihydroxyadenine is insoluble at physiological urinary pH but as marked supersaturation is possible the manifestations differ: there may be minimal consequences, there may be infiltration of the tubulointerstitial tissue with acute or chronic damage or there may be stone formation in the urinary tract. Effective treatment can be offered and therefore the prognosis depends upon the renal function at diagnosis. Treatment consists of adequate fluid intake, a low-purine diet and administration of allopurinol. Urinary 2,8-dihydroxyadenine crystals are easily recognized under a microscope. The diagnosis of 2,8-dihydroxyadeninuria can be confirmed by estimation of adenine phosphoribosyltransferase activity in erythrocyte lysates. More than 300 cases of 2,8-dihydroxyadeninuria have been diagnosed worldwide, most of them in Japan, France and Iceland. One case has been reported in Finland but there have been no reports from the Scandinavian peninsula or from Denmark. The relevant mutations may be very rare in these countries but underdiagnosis is also possible.
50bp deletion in the promoter for superoxide dismutase 1 (SOD1) reduces SOD1 expression in vitro and may correlate with increased age of onset of sporadic amyotrophic lateral sclerosis.
The objective was to test the hypothesis that a described association between homozygosity for a 50bp deletion in the SOD1 promoter 1684bp upstream of the SOD1 ATG and an increased age of onset in SALS can be replicated in additional SALS and control sample sets from other populations. Our second objective was to examine whether this deletion attenuates expression of the SOD1 gene. Genomic DNA from more than 1200 SALS cases from Ireland, Scotland, Quebec and the USA was genotyped for the 50bp SOD1 promoter deletion. Reporter gene expression analysis, electrophoretic mobility shift assays and chromatin immunoprecipitation studies were utilized to examine the functional effects of the deletion. The genetic association for homozygosity for the promoter deletion with an increased age of symptom onset was confirmed overall in this further study (p=0.032), although it was only statistically significant in the Irish subset, and remained highly significant in the combined set of all cohorts (p=0.001). Functional studies demonstrated that this polymorphism reduces the activity of the SOD1 promoter by approximately 50%. In addition we revealed that the transcription factor SP1 binds within the 50bp deletion region in vitro and in vivo. Our findings suggest the hypothesis that this deletion reduces expression of the SOD1 gene and that levels of the SOD1 protein may modify the phenotype of SALS within selected populations.
The -629C>A polymorphism in the CETP gene does not explain the association of TaqIB polymorphism with risk and age of myocardial infarction in Icelandic men.
The aim of this study was to examine whether the well-established effect of the common TaqIB polymorphism in intron 1 of the gene for cholesterol ester transfer protein (CETP) on high density lipoprotein cholesterol (HDL-C) concentration and increased risk of myocardial infarction (MI), could be explained by the recently identified -629C>A functional polymorphism in the promoter. Non-fatal MI cases (388 male) and a control group of 794 healthy men were recruited from the 30 year long prospective Reykjavik Study. In the healthy men the frequency of the TaqIB B2 allele was 0.47 (95% CI: 0.44-0.50) and there was a strong allelic association with the -629A allele (D=-0.21, P
The article is devoted to the role of insertion-deletion polymorphism of -2-adrenoreceptor gene in development of hereditary disorders of cardiac conduction. We examined 71 patients with atrioventricular blocks and 92 patients with sick sinus node syndrome. Statistically significant preponderance of homozygous genotype DD of ADRA2B gene was found in both groups. Associations of alleles with male or female gender were also revealed.
The ABCB1, rs9282564, AG and TT genotypes and the COMT, rs4680, AA genotype are less frequent in deceased patients with opioid addiction than in living patients with opioid addiction
Sudden death due to acute intoxication occurs frequently in patients with opioid addiction (OA). To examine whether certain genotypes were associated with this, we examined the frequencies of 29 SNPs located in candidate genes related to opioid pharmacology: ABCB1, OPRM1, UGT2B7, CYP3A5, CYP2B6, CYP2C19, CYP2D6, COMT, KCNJ6 and SCN9A in 274 deceased patients with OA (DOA), 309 living patients with OA (LOA) and in 394 healthy volunteers (HV). The main hypothesis of the study was that subjects homozygous for the variant 3435T in ABCB1 (rs1045642) occur more frequently in DOA than in LOA and HV because morphine and methadone more readily cross the blood barrier in these subjects due to a lower efflux transporter activity of the ABCB1 (p-glycoprotein) transporter. Our results did not support this hypothesis, because no statistically significant difference (p = 0.506) in the frequency of the TT genotype of rs1045642 was observed between the DOA, LOA and HV cohorts. However, for another ABCB1 variant, rs9282564, we found that the frequencies of the AG and TT genotypes were 13, 21 and 25% in DOA, LOA and HV, respectively, and after correcting for age, sex and multiple testing, the differences between DOA and LOA were statistically significantly different (p = 0.027). The COMT rs4680 AA genotype frequencies were 25%, 35% and 31% in DOA, LOA and HV, respectively, and the difference between DOA and LOA was also statistically significant (p = 0.0028). In conclusion, this study generated two hypotheses suggesting possible associations of a reduced risk of death and carrying, respectively, the ABCB1 rs9282564 AG and TT genotypes and the COMT rs4680 AA genotype among patients with OA. These findings should be confirmed in independent cohorts, and if a causal relationship between these variants and fatal poisoning in OA is confirmed, then it may be possible at least in theory to personalize prevention of sudden death in this patient group.
Homozygosity for a premature stop codon at amino acid position 577 in the alpha-actinin-3 (ACTN3) gene leads to a-actinin-3 deficiency. This genotype is observed in approximately 18% of Caucasians. The ACTN3 R577X polymorphism has been previously associated with indicators of physical performance in several, but not all, studies. We examined the prevalence of R577X (rs1815739) and two additional haplotype tagging single nucleotide polymorphisms (htSNPs) of the ACTN3 gene (rs1791690 and rs2275998) in the Genathlete study comprising 316 male elite endurance athletes (VO2max 79.0+3.5 ml · kg(-1) · min(-1); mean +/- s) from North America, Finland, and Germany and 304 sedentary controls (VO2max 40.1+7.0 ml · kg(-1) · min(-1) matched by country of origin. The distribution of genotype and allele frequencies between the two groups was tested by Pearson chi-square and/or Fischer exact test. The prevalence of the 577X homozygote genotype was similar in endurance athletes and controls (20% and 17.5%, respectively). The resulting odds ratio for endurance performance in 577X homozygotes compared with 577R-allele carriers was 1.24 (95%CI 0.82-1.87, P = 0.3). The genotype distribution of the two htSNPs and haplotype frequencies did not differ significantly between athletes and controls. In conclusion, our findings indicate that ACTN3 R577X and other SNPs in ACTN3 are not genetic determinants of endurance performance in Caucasian males.
A single factor V gene G-A mutation (Arg506Gln) underlying activated protein C (APC) resistance is a common risk factor for venous thromboembolism. It is still unclear whether the factor V Leiden predisposes patients to arterial thrombosis and myocardial infarction (MI). To determine a correlation between the factor V Leiden mutation and MI in different age categories, DNA samples from 287 patients with "early" and "late" MI were investigated. As control groups 373 young subjects (mean age 11 years) and 110 elderly ones (mean age 80 years) were studied. We found a significant difference in mutant allele distribution in the "late" MI group compared to the "early" MI group (chi2 = 9.86, OR = 13,7, P
[A genetic and demographic study of Dagestan highland populations and migrants to the lowlands. The relationship between levels of consanguinity, homozygosity and physiologic sensitivity].
This is a continuation of a series of papers devoted to studying the genetic mechanisms of adaptation in migrants from isolated highland populations of Dagestan to new ecological conditions (lowlands). This paper describes the main results of studying the relationship between levels of inbreeding, homozygosity, and physiological sensitivity. Earlier, we found that decreased resistance to changing environmental factors in migrants to lowlands from the Dagestan highlands was connected with their high level of homozygosity. The data obtained allow us to assume that missing links in this chain of events include, in addition to parameters of inbreeding level, parameters of neurophysiological sensitivity, including absolute and differential sensitivity of various analyzers sensory systems, which are from 65 to 75% genetically determined. Migrants from highland auls (villages) to lowlands exhibited a decreased rate of sensomotor reactions in response to light and sound of various intensities, as well as decreased differential color sensitivity in the long-, medium-, and short-wave ranges of the spectrum, compared to highlanders. The results suggest the selective mortality of migrants from highlands to lowlands during adaptation to new conditions. Those migrants who dies were characterized by specific gene complexes that determined the characteristic features of expression of a number of interrelated polymorphic and quantitative traits. Thus, the high levels of homozygosity and inbreeding were accompanied by a greater neurophysiological sensitivity and lower indices of body weight and height.
