MUTATION AND HAPLOTYPE ANALYSIS OF PHENYLALANINE-HYDROXYLASE ALLELES IN CLASSICAL PKU PATIENTS FROM THE CZECH-REPUBLIC - IDENTIFICATION OF 4 NOVEL MUTATIONS

Mutations, haplotypes, and other polymorphic markers in the phenylalan ine hydroxylase (PAH) gene were analysed in 133 unrelated Czech famili es with classical phenylketonuria (PKU). Almost 95% of all mutant alle les were identified, using a combination of PCR and restriction analys is, denaturing gradient gel electrophoresis (DGGE), and sequencing. A total of 30 different mutations, 16 various RFLP/VNTR haplotypes, and four polymorphisms were detected on 266 independent mutant chromosomes . The most common molecular defect observed in the Czech population wa s R408W (54.9%). Each of the other 29 mutations was present in no more than 5% of alleles and 13 mutations were found in only one PKU allele each (0.4%). Four novel mutations G239A, R270fsde15bp, A342P, and IVS 11nt-8g-->a were identified. In 14 (5.1%) alleles, linked to four diff erent RFLP/VNTR haplotypes, the sequence alterations still remain unkn own. Our results confirm that PKU is a heterogeneous disorder at the m olecular level. Since there is evidence for the gene flow coming hom n orthern, western, and southern parts of Europe into our Slavic populat ion, it is clear that human migration has been the most important fact or in the spread of PKU alleles in Europe.