Characteristics of myotonic dystrophy in Istria: Molecular genetic approach. Part II: Analysis of genetic polymorphisms

One of the world highest prevalence estimates of myotonic dystrophy (DM) ha s been reported in the Croatian region Istria. To analyse the population ge netic characteristics of DM locus in Istria, two intragenic and three extra genic polymorphic markers were tested. The Southern blot technique was used for D19S63 locus analysis, whereas PCR analysis was performed for CKMM, Al u polymorphism, DMPK (G/T) int ron 9/HinfI polymorphism, and D19S207 geneti c markers. The compound haplotypes segregating with DM were established. A complete association between the DM mutation and D29S63, D19S207, intron 9/ HinfI polymorphism and Alu polymorphism markers were found. In all DM chrom osomes: D19S63 and Alu markers had the allele 1 in common; D19S207 had the allele 3 in common, DMPK (G/T) intron 9/HinfI markers had the allele 2 in c ommon. The analysis of CKMM polymorphism revealed genotype heterogeneity; i n DM chromosomes either allele 2 or allele 4 were found. The haplotype analysis in the population of Croatian Istria supports the li nkage disequilibrium between the DM mutation and Alu polymorphism, intron 9 /HinfI polymorphism, D19S63 and D19S207 markers as reported worldwide. The results of the haplotype analysis suggest a common origin of the mutation i n Istrian population.