Michaela Blažková

Polymorphisms in the RAGE gene influence susceptibility to diabetes-associated microvascular dermatoses in NIDDM

To examine genetic polymorphism in the complete sequence of the Receptor of Advanced Glycation End products (RAGE) gene and its possible associations with diabetes-associated microvascular dermatoses (DAMD). Further, to analyze the distribution of individual genotype combinations on the particular polymorphic loci in the RAGE gene. A part of the RAGE gene spanning a region from -4 to 3334 bp was analyzed on a set of 45 subjects with non-insulin dependent diabetes mellitus (NIDDM) and parallel DAMD by means of PCR with subsequent heteroduplex and single-strand conformation polymorphism (SSCP) analyses. Allele frequencies and genotype combinations of novel common polymorphisms were determined in an associations study comprising four groups of subjects (n=390). Fourteen novel polymorphisms (R77C, V89V, 718G/T, 1704G/T, 1727A1728ins, H305Q, S307C, 2117A/G, 2184A/G, 2245G/A, 2249A/G, 2741G/A, and 3089ACdel) and one described previously (G82S) were identified. Significant association with microvascular dermatoses (MD) irrespective of NIDDM were found for exon mutation 82S (P= .004, after a correction for the number of comparisons P(corr) < .05) and marginally significant for intron variant 1704T (P= .032, P(corr)> .05). Calculated odds ratios for 82S and 1704T were 4.73 (95% CI, 1.51 to 14.77) and 1.73 (95% CI, 0.93 to 3.22), respectively. Certain individual genotype combinations of G82S, 1704G/T, and 2184A/G were significantly associated with the presence of MD (P= .00647) both in diabetic and non-diabetic study populations. The two novel polymorphisms (1704G/T and 2184A/G) together with the G82S were shown to influence the susceptibility to MD independent of diabetes itself.

Ultrafast detection of microsatellite repeat polymorphism in endothelin 1 gene by electrophoresis in short capillaries

The methodology and instrumentation for fast denaturing electrophoresis in short capillaries was developed and exemplified by detection of short tandem repeat polymorphism in the endothelin 1 gene. The resolution of two nucleotides, which is required for the detection of a dinucleotide repeat polymorphism, was achieved in a capillary of an effective length of 2.5 cm at a temperature of 60°C and an electric field strength of 600 V/cm in 42 s. Thus, the use of denaturing electrophoresis in short capillaries with laser‐induced fluorescence detection resulted in a reduction of analysis time by a factor of 200 when compared to the conventional slab gel electrophoresis. The developed methodology and instrumentation is advantageous for an implementation in clinical diagnostics and genetic population screening where fast analytical instrumentation amenable to automation is of paramount importance.

Phenylketonuria mutations and their relation to RFLP haplotypes at the PAH locus in Czech PKU families

A detailed study of the mutant phenylalanine hydroxylase (PAH) gene from the eastern part of the Czech Republic (Moravia) is reported. A total of 190 mutant alleles from 95 phenylketonuria (PKU) families were analyzed for 21 prevalent Caucasian mutations and restriction fragment length polymorphism /variable number of tandem repeats (RFLP/VNTR) haplotypes. Eighty per cent of all mutant alleles were found to carry 11 mutations. The most common molecular defect was the mutation R408W (55.3%), with a very high degree of homozygosity (34.6%). Each of four other mutations (R158Q, R243X, G272X, IVS12nt1) accounted for more than 3% of PKU alleles. Rarely present were mutations IVS10nt546 (2.6%), R252W (2.6%), L48S (2.1%), R261Q (1.6%), Y414C (1.0%) and I65T (0.5%). Mutations that have been predominantly described in southern Europe (IVS7nt1, A259V, Y277D, R241H, T278N) were not detected. A total of 14 different mutant haplotypes were observed. Three unusual genotype-haplotype associations were identified (R158Q on haplotypes 2.3 and 7.8 and R252W on haplotype 69.3). There was a strong association between the mutation R408W and haplotype 2.3 (54.7%). Heterogeneity was found at mutations R408W (haplotypes 2.3 and 5.9), R158Q (haplotypes 4.3, 2.3 and 7.8) and IVS10nt546 (haplotypes 6.7 and 34.7). The molecular basis of PKU in the Moravian area appears to be relatively homogeneous in comparison with other southern and western European populations, thus providing a good starting point for prenatal diagnosis and early clinical classification.