Genotype‐phenotype correlations and BH₄ estimated responsiveness in patients with phenylketonuria from Rio de Janeiro, Southeast Brazil

Abstract

The high discordance rate between genotype-predicted and observed metabolic phenotypes in this study seems to be due partially to the high frequency of the so-called "moderate" common mutations, p.R261Q, p.V388M, and p.I65T, which are reported to be associated to erratic or more severe than expected metabolic phenotypes. Although our results of BH₄ estimated responsiveness must be regarded as tentative, it should be emphasized that genotyping and genotype-phenotype association studies are important in selecting patients to be offered a BH₄ overload test, especially in low-resource settings like Brazil.