The Genetic Landscape and Epidemiology of Phenylketonuria

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 gt 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 gt T (p.Arg408Trp) (22.2%), c.1066-11G gt A (IVS10-11G gt A) (6.4%), and c.782G gt A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066-11G gt A];[1066-11G gt 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

The Genetic Landscape and Epidemiology of Phenylketonuria

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.Fil: Hillert, Alicia. No especifíca;Fil: Anikster, Yair. No especifíca;Fil: Belanger Quintana, Amaya. No especifíca;Fil: Burlina, Alberto. No especifíca;Fil: Burton, Barbara K.. No especifíca;Fil: Carducci, Carla. No especifíca;Fil: Chiesa, Ana Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Gobierno de la Ciudad de Buenos Aires. Centro de Investigaciones Endocrinológicas "Dr. César Bergada". Fundación de Endocrinología Infantil. Centro de Investigaciones Endocrinológicas "Dr. César Bergada"; ArgentinaFil: Christodoulou, John. No especifíca;Fil: Dordevic, Maja. No especifíca;Fil: Desviat, Lourdes R.. No especifíca;Fil: Eliyahu, Aviva. No especifíca;Fil: Evers, Roeland A.F.. No especifíca;Fil: Fajkusova, Lena. No especifíca;Fil: Feillet, Francois. No especifíca;Fil: Bonfim Freitas, Pedro E.. No especifíca;Fil: Gizewska, María. No especifíca;Fil: Gundorova, Polina. No especifíca;Fil: Karall, Daniela. No especifíca;Fil: Kneller, Katya. No especifíca;Fil: Kutsev, Sergey I.. No especifíca;Fil: Leuzzi, Vincenzo. No especifíca;Fil: Levy, Harvey L.. No especifíca;Fil: Lichter Koneck, Uta. No especifíca;Fil: Muntau, Ania C.. No especifíca;Fil: Namour, Fares. No especifíca;Fil: Oltarzewsk, Mariusz. No especifíca;Fil: Paras, Andrea. No especifíca;Fil: Perez, Belén. No especifíca;Fil: Polak, Emil. No especifíca;Fil: Polyakov, Alexander V.. No especifíca;Fil: Porta, Francesco. No especifíca;Fil: Rohrbach, Marianne. No especifíca;Fil: Scholl Bürgi, Sabine. No especifíca;Fil: Spécola, Norma. No especifíca;Fil: Stojiljkovic, Maja. No especifíca;Fil: Shen, Nan. No especifíca;Fil: Santana da Silva, Luiz C.. No especifíca;Fil: Skouma, Anastasia. No especifíca;Fil: van Spronsen, Francjan. No especifíca;Fil: Stoppioni, Vera. No especifíca;Fil: Thöny, Beat. No especifíca;Fil: Trefz, Friedrich K.. No especifíca;Fil: Vockley, Jerry. No especifíca;Fil: Yu, Youngguo. No especifíca;Fil: Zschocke, Johannes. No especifíca;Fil: Hoffmann, Georg F.. No especifíca;Fil: Garbade, Sven F.. No especifíca;Fil: Blau, Nenad. No especifíca

Genotypes of 2579 patients with phenylketonuria reveal a high rate of BH4 non-responders in Russia.

Phenylalanine hydroxylase (PAH) deficiency is responsible for most cases of phenylketonuria (PKU). Furthermore, numerous studies on BH4-sensitive PAH deficiency have been conducted. To date, BH4, a cofactor of PAH, has not been used to treat PKU in Russia.Genotype data of patients with PKU can be used to predict their sensitivity to BH4 therapy. A cohort of 2579 patients with PKU from Russia was analyzed for 25 common PAH gene mutations using custom allele-specific multiplex ligation-dependent probe amplification-based technology. A mutation detection rate of 84.1% chromosomes was accomplished. Both pathogenic alleles were identified in 73.1% of patients. The most frequent pathogenic variants were p.Arg408Trp (50.9%), p.Arg261Gln (5.3%), p.Pro281Leu (3.5%), IVS12+1G>A (3.1%), IVS10-11G>A (2.6%), and p.Arg158Leu (2.4%). The exact boundaries of a PAH exon 5 deletion were defined as EX5del4154ins268 (c.442-2913_509+1173del4154ins268). Severe phenotypes prevailed in the cohort, and classical PKU was observed in 71.8% cases. Due to the genotype-based prediction, 55.9% of the probands were non-responders to the BH4-treatment, and 20.2% were potential responders. Analysis of genotype data is useful to predict BH4 response in PKU patients. The high rate of non-responders among Russian patients was due to the high allele frequency of severe PAH mutations

Molecular-genetic causes for the high frequency of phenylketonuria in the population from the North Caucasus

<div><p>Phenylketonuria is an inherited disease caused by mutations in the phenylalanine hydroxylase gene <i>PAH</i>. Different <i>PAH</i> pathogenic variants occur in different ethnic groups with various frequencies and the incidence of the disease itself varies from country to country. In the Caucasus region of Russia, some ethnoses are geographically and culturally isolated from each other. The tradition of monoethnic marriages may cause decreased genetic variability in those populations. In the Karachay-Cherkess Republic (Russia), the highest incidence of phenylketonuria in the world has been detected (1:850 newborns) in the region and 1:332 among the titular nation Karachays. Here, we showed that this phenomenon is due to the widespread prevalence of the p.Arg261* variant. Its allele frequency among Karachay patients with PKU was 68.4% and the carrier frequency in Karachays was 1:16 healthy individuals. <i>PAH</i> haplotype analysis showed a unique common origin. The founder haplotype and mutation “age” were estimated by analyzing the linkage disequilibrium between p.Arg261* and extragenic short tandem repeat loci. The p.Arg261* variant occurred in the Karachays population 10.2 ± 2.7 generations ago (275 ± 73 years) and its spread occurred in parallel with the growth of the population.</p></div

Linkage disequilibrium analysis between the p.Arg261* variant in Karachays and microsatellites close to the <i>PAH</i> gene.

<p>Linkage disequilibrium analysis between the p.Arg261* variant in Karachays and microsatellites close to the <i>PAH</i> gene.</p

Survey data of healthy KCR residents.

<p>Survey data of healthy KCR residents.</p

Haplotypes of p.Arg261*-bearing chromosomes at five microsatellite loci.

<p>Haplotypes of p.Arg261*-bearing chromosomes at five microsatellite loci.</p

Karachay population dynamics from 1790 to 2010.

<p>The dots indicate the population numbers of the Karachay population [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0201489#pone.0201489.ref027" target="_blank">27</a>]. The curve is the approximation of exponential dependence on the graph of abundance versus time. The point of p.Arg261* origin is marked by an arrow; the error interval is in a square.</p

Epidemiology of Hereditary Diseases in the Karachay-Cherkess Republic

Prevalence and allelic heterogeneity of hereditary diseases (HDs) could vary significantly in different human populations. Current knowledge of HDs distribution in populations is generally limited to either European data or analyses of isolated populations which were performed several decades ago. Thus, an acknowledgement of the HDs prevalence in different modern open populations is important. The study presents the results of a genetic epidemiological study of hereditary diseases (HDs) in the population of the Karachay-Cherkess Republic (KChR). Clinical screening of a population of 410,367 people for the identification of HDs was conducted. The population surveyed is represented by five major ethnic groups&mdash;Karachays, Russians, Circassians, Abazins, Nogais. The study of the populations was carried out in accordance with the proprietary protocol of genetic epidemiological examination designed to identify &gt;3500 HDs easily diagnosed during clinical examination by qualified specialists specializing in the HDs. The protocol consists of the population genetic and medical genetic sections and is intended for comprehensive population analysis based on the data on different genetic systems, including the genes of HDs, DNA polymorphisms, demographic data collected during hospital-based survey. 8950 families (with 10,125 patients) with presumably the HDs were initially identified as a result of the survey and data collection through various sources of registration (from 1156 medical workers from 163 medical institutions). A diagnosis of hereditary pathology was established in 1849 patients (from 1295 families). Two hundred and thirty nosological forms were revealed (in 1857 patients from 1295 families). The total prevalence of HDs was 1:221. Differences between populations and ethnic groups were identified: 1:350 in Russians, 1:195 in Karachays, 1:199 in Circassians, 1:218 in Abazins, 1:135 in Nogais. Frequent diseases were determined, the presence of marked genetic heterogeneity was identified during the confirmatory DNA diagnosis. To explain the reasons for the differentiation of populations by load of HD, a correlation analysis was carried out between the FST (random inbreeding) in populations and HDs load values. This analysis showed genetic drift is probably one of the leading factors determining the differentiation of KChR populations by HDs load. For the first time, the size of the load and spectrum of HDs in the populations of the KChR are determined. We have demonstrated genetic drift to be one of the main factors of the population dynamics in studied population. A significant genetic heterogeneity of HDs, both allelic and locus, was revealed in KChR