In order to characterize the molecular heterogeneity of phenylalanine
hydroxylase deficiencies in the Spanish population, 37 PKU patients we
re initially screened for 16 known European mutations. For the remaini
ng unidentified alleles, we used a combined strategy based on single s
trand conformation polymorphism analysis and DNA sequencing. Overall,
a total of 15 different mutations were found in our sample, which acco
unt for 62% of the total mutant alleles. We also investigated the asso
ciation between the mutations, haplotypes and variable number of tande
m repeats described on the phenylalanine hydroxylase gene. In addition
, we analyzed the geographical distribution in Spain of the two most p
revalent mutations in our population: IVS10 and I65T.