Haplotype analysis of classical and mild phenotype of phenylketonuria in the German Democratic Republic.

The restriction fragment length polymorphism (RFLP)-haplotypes have been analysed in 16 families from the northern part of the GDR at risk for classical and mild phenylketonuria (PKU). Ten different RFLP haplotypes associated with the normal and mutant phenylalanine hydroxylase (PAH) alleles were identified. Of the 32 mutant alleles analysed, 29 (90.6%) were associated with haplotypes 1, 2, 3 and 4; 53.1% of the mutant alleles were linked with haplotype 2. The distribution of RFLP haplotypes in 16 patients of clinical different PKU phenotypes (classical and mild) is reported.