THE ANALYSIS OF THE MUTATIONS IN ALG6 GENE BY PCR-SSCP METHOD S. Šupraha and J. Dumić Department of Biochemistry and Molecular Biology, Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kovačića 1, Zagreb, Croatia ; e-mail: jdumic@pharma.hr ; sandras@pharma.hr Congenital disorders of glycosylation (CDGs) are inherited autosomal recessive disorders caused by defects in the pathways of N- and O-linked glycosylation. The frequency of the diseases and the frequency of the healthy carriers (usually heterozygous) are inconsistent, as shown by some population studies. We have recently undertaken a comprehensive project to determine the frequency of various mutations/polymorphisms in genes encoding glycosyltransferases related to CDGs in Croatian population. One of the most common types of CDGs is type Ic, caused by mutations in hALG6 gene encoding Man(9)GlcNAc(2)-PP-Dol α 1, 3-glucosyltransferase. Sixteen different hALG6 mutations causing CDG-Ic have been described so far, where A333V accounts for the majority of the alleles. Here we report a new PCR-SSCP method optimized for the analysis of mutations in the exon 11 of hALG6 gene and present results obtained by screening of 350 healthy unrelated Croats. The multiplied DNA fragments encompassing exon 11 of hALG6 genes were subjected to electrophoresis under different conditions. The best separation was obtained on 6% PAG, at 4 C for 5 hours using 6W. In the samples analyzed until now A333V mutation has not been identified.