The Genetic Landscape and Epidemiology of Phenylketonuria

Alicia Hillert, Yair Anikster, Amaya Belanger-Quintana, Alberto Burlina, Barbara K. Burton, Carla Carducci, Ana E. Chiesa, John Christodoulou, Maja Đorđević, Lourdes R. Desviat, Aviva Eliyahu, Roeland A.F. Evers, Lena Fajkusova, François Feillet, Pedro E. Bonfim-Freitas, Maria Giżewska, Polina Gundorova, Daniela Karall, Katya Kneller, Sergey I. KutsevVincenzo Leuzzi, Harvey L. Levy, Uta Lichter-Konecki, Ania C. Muntau, Fares Namour, Mariusz Oltarzewski, Andrea Paras, Belen Perez, Emil Polak, Alexander V. Polyakov, Francesco Porta, Marianne Rohrbach, Sabine Scholl-Bürgi, Norma Spécola, Maja Stojiljković, Nan Shen, Luiz C. Santana-da Silva, Anastasia Skouma, Francjan van Spronsen, Vera Stoppioni, Beat Thöny, Friedrich K. Trefz, Jerry Vockley, Youngguo Yu, Johannes Zschocke, Georg F. Hoffmann, Sven F. Garbade, Nenad Blau

Research output: Contribution to journalArticlepeer-review


Phenylketonuria (PKU), caused by variants in the phenylalanine hydroxylase (PAH) gene, is the most common autosomal-recessive Mendelian phenotype of amino acid metabolism. We estimated that globally 0.45 million individuals have PKU, with global prevalence 1:23,930 live births (range 1:4,500 [Italy]–1:125,000 [Japan]). Comparing genotypes and metabolic phenotypes from 16,092 affected subjects revealed differences in disease severity in 51 countries from 17 world regions, with the global phenotype distribution of 62% classic PKU, 22% mild PKU, and 16% mild hyperphenylalaninemia. A gradient in genotype and phenotype distribution exists across Europe, from classic PKU in the east to mild PKU in the southwest and mild hyperphenylalaninemia in the south. The c.1241A>G (p.Tyr414Cys)-associated genotype can be traced from Northern to Western Europe, from Sweden via Norway, to Denmark, to the Netherlands. The frequency of classic PKU increases from Europe (56%) via Middle East (71%) to Australia (80%). Of 758 PAH variants, c.1222C>T (p.Arg408Trp) (22.2%), c.1066−11G>A (IVS10−11G>A) (6.4%), and c.782G>A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066−11G>A];[1066−11G>A] (2.6%). Most genotypes (73%) were compound heterozygous, 27% were homozygous, and 55% of 3,659 different genotypes occurred in only a single individual. PAH variants were scored using an allelic phenotype value and correlated with pre-treatment blood phenylalanine concentrations (n = 6,115) and tetrahydrobiopterin loading test results (n = 4,381), enabling prediction of both a genotype-based phenotype (88%) and tetrahydrobiopterin responsiveness (83%). This study shows that large genotype databases enable accurate phenotype prediction, allowing appropriate targeting of therapies to optimize clinical outcome.

Original languageEnglish
Pages (from-to)234-250
Number of pages17
JournalAmerican Journal of Human Genetics
Issue number2
StatePublished - 6 Aug 2020


  • BH4
  • PAH deficiency
  • PKU
  • hyperphenylalaninemia
  • phenylalanine
  • tetrahydrobiopterin


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