The PAH activity landscape web resource is a database on PAH genotypes and genotype-specific PAH enzymatic function. The Map (more information here) gives an overview on the regional distribution of most common PAH gentoypes in Europe and the Middle East and links to country-specific information on genotypes. The Activity Landscapes (more information here) provide information on PAH enzyme function associated with specific genotypes. This database is intended to further the understanding of PAH function in the individual patient's situation, taking different metabolic or therapeutic states into account. Moreover, the information provided may support clinicians in designing personalized treatment strategies for patients suffering from PAH deficiency. The web resource will be continuously expanded and users can request genotype-specific PAH activity landscapes, where data is not available.