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

Alternative Therapies for PKU

The phenylalanine (PHE)-restricted diet has improved in quality and diversity over time and has proven to be effective in all patients. Nevertheless, this treatment imposes a heavy social and economic burden to patient and family and impacts quality of life. Sustained adherence to PHE restriction is difficult to maintain. Moreover, even patients with phenylketonuria (PKU) with normal intelligence quotient (IQ) have lower IQ than matched individuals without PKU and can have deficits in multiple other aspects of neuropsychological function, including cognitive and executive function, working memory. They can also have behavior problems, depression, and low self-esteem. In recent years, alternative treatments for PKU have been developed and their use has been indicated for some patients who are candidates for options besides traditional treatment. Sapropterindihydrochloride, large neutral amino acids, and glycomacropeptide are alternative treatment options in use for selected patients. The aim of this article is to review the current knowledge of these new approaches to PKU treatment

Ten years of screening for congenital disorders of glycosylation in Argentina: Case studies and pitfalls

Background: Congenital Disorders of Glycosylation (CDG) are genetic diseases caused by hypoglycosylation of glycoproteins and glycolipids. Most CDG are multisystem disorders with mild to severe involvement. Methods: We studied 554 patients (2007–2017) with a clinical phenotype compatible with a CDG. Screening was performed by serum transferrin isoelectric focusing. The diagnosis was confirmed by genetic testing (Sanger or exome sequencing). Results: A confirmed abnormal pattern was found in nine patients. Seven patients showed a type 1 pattern: four with PMM2-CDG, two with ALG2-CDG, and one with classical galactosemia. A type 2 pattern was found in two patients: one with a CDG-IIx and one with a transferrin protein variant. Abnormal transferrin pattern were observed in a patient with a myopathy due to a COL6A2 gene variant. Conclusions: CDG screening in Argentina from 2007 to 2017 revealed 4 PMM2-CDG patients, 2 ALG2-CDG patients with a novel homozygous gene variant and 1 CDG-IIx.Fil: Asteggiano, Carla Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Universidad Católica de Córdoba; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Papazoglu, Gabriela Magali. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; Argentina. Universidad Católica de Córdoba; ArgentinaFil: Bistue Millon, Maria Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; Argentina. Universidad Católica de Córdoba; ArgentinaFil: Peralta, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Católica de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Azar, Nydia Beatríz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Universidad Católica de Córdoba; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Spécola, Norma. Municipalidad de La Plata. Hospital de Niños; ArgentinaFil: Guelbert, Norberto Bernardo. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Suldrup, Niels. Iaca Laboratorios; ArgentinaFil: Pereyra, Marcela. Gobierno de la Provincia de Mendoza. Hospital Pediátrico Humberto Notti; ArgentinaFil: Dodelson de Kremer, Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; Argentina. Universidad Católica de Córdoba; Argentin

Adherence to PKU guidelines among patients with phenylketonuria: A cross-sectional national multicenter survey-based study in Argentina, Brazil, and Mexico

Objective: To characterize adherence to Phenylketonuria (PKU) management practices among PKU patients treated at reference sites around Argentina, Brazil, and Mexico. Methods: This is a retrospective, observational, multicenter, and multinational survey-based study using aggregate data. From an initial list of 40 sites, 22 clinicians expressed interest in completing the survey, with 20 clinicians from 20 unique sites fulfilling all the study criteria. The Survey contained 28 questions, including respondent's clinic characteristics, clinic PKU treatment recommendations, and patient adherence to clinic recommendations. Survey was available in local languages, and the respondents were asked to consult their clinic records to complete their responses. Adherence was assessed by target blood phenylalanine (Phe), target blood testing frequency, and clinic visits. Results: A total of 1077 (out of 1377) actively managed PKU patients (seen in the clinic in the last 3 years) from 13 clinics in Brazil, six in Argentina, and one in Mexico were analyzed. Upper blood Phe target was set over 360 μMol/L in 70% of the clinics for adult patients. Around 40% of the patients >30 years old had Phe blood tests done twice a year or less, with 60% of the clinics recommending semestral visits for adults <30 years old. Twice a month was the most common frequency of visits for <1 year old. The COVID-19 pandemic was a disruptor for frequency of visits and exams. Conclusions: These results show that there is still room for improvement in terms of adherence, namely in adults and older children. More efforts must be made to educate patients and healthcare professionals about the importance of treatment adherence, accompanied by public policies that expand access to pharmacological and dietary treatment with diversity and quality to improve adherence to adequate blood Phe levels

Ten years of screening for congenital disorders of glycosylation in Argentina: case studies and pitfalls

Background: Congenital Disorders of Glycosylation (CDG) are genetic diseases caused by hypoglycosylation of glycoproteins and glycolipids. Most CDG are multisystem disorders with mild to severe involvement. Methods: We studied 554 patients (2007–2017) with a clinical phenotype compatible with a CDG. Screening was performed by serum transferrin isoelectric focusing. The diagnosis was confirmed by genetic testing (Sanger or exome sequencing). Results: A confirmed abnormal pattern was found in nine patients. Seven patients showed a type 1 pattern: four with PMM2-CDG, two with ALG2-CDG, and one with classical galactosemia. A type 2 pattern was found in two patients: one with a CDG-IIx and one with a transferrin protein variant. Abnormal transferrin pattern were observed in a patient with a myopathy due to a COL6A2 gene variant. Conclusions: CDG screening in Argentina from 2007 to 2017 revealed 4 PMM2-CDG patients, 2 ALG2-CDG patients with a novel homozygous gene variant and 1 CDG-IIx.Fil: Asteggiano, Carla Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Universidad Católica de Córdoba; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Papazoglu, Gabriela Magali. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; Argentina. Universidad Católica de Córdoba; ArgentinaFil: Bistue Millon, Maria Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; Argentina. Universidad Católica de Córdoba; ArgentinaFil: Peralta, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Católica de Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Azar, Nydia Beatríz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Universidad Católica de Córdoba; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Spécola, Norma. Municipalidad de La Plata. Hospital de Niños; ArgentinaFil: Guelbert, Norberto Bernardo. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; ArgentinaFil: Suldrup, Niels. Iaca Laboratorios; ArgentinaFil: Pereyra, Marcela. Gobierno de la Provincia de Mendoza. Hospital Pediátrico Humberto Notti; ArgentinaFil: Dodelson de Kremer, Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Medicina. Centro de Estudios de las Metabolopatías Congénitas; Argentina. Gobierno de la Provincia de Córdoba. Ministerio de Salud. Hospital de Niños de la Santísima Trinidad; Argentina. Universidad Católica de Córdoba; Argentin