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Upadia J, Crivelly K, Noh G, Cunningham A, Cerminaro C, Li Y, Mckoin M, Chenevert M, Andersson HC. Maximal dietary responsiveness after tetrahydrobiopterin (BH4) in 19 phenylalanine hydroxylase deficiency patients: What super-responders can expect. Mol Genet Metab Rep 2024; 38:101050. [PMID: 38469087 PMCID: PMC10926188 DOI: 10.1016/j.ymgmr.2024.101050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 03/13/2024] Open
Abstract
Background Inherited phenylalanine hydroxylase deficiency, also known as phenylketonuria (PKU), causes poor growth and neurologic deficits in the untreated state. After ascertainment through newborn screen and dietary phenylalanine (Phe) restriction to achieve plasma Phe in the range of 120-360 μmol/L, these disease manifestations can be prevented. Poor compliance with protein restricted diets supported by medical food is typical in later years, beginning in the late toddler and teenage years. Pharmacologic doses of oral tetrahydrobiopterin (BH4; sapropterin dihydrochloride) is effective in reducing plasma Phe in about 40-50% of PKU patients but effectiveness is highly variable. Objective To assess the maximal responsiveness to 20 mg/kg/day oral BH4 as it affects plasma Phe and dietary Phe allowance in PKU patients. Materials and methods This was a single-center, retrospective observational study, combining case reports of individual patients. We reported an outcome of 85 patients with PKU who were trialed on BH4. Phe levels and dietary records of 19 BH4 "super-responders" were analyzed. Results Overall, 63.5% of the patients (54/85) were considered BH4 responders. However, we quantitated the dietary liberalization of 19 of our responsive patients (35%), those with at least a 2-fold increase in dietary Phe and maintenance of plasma Phe in treatment range. In these "super-responders", the mean plasma Phe at baseline was 371 ± 237 μmol/L and decreased to 284 ± 273 μmol/L after 1 year on BH4. Mean dietary Phe tolerance increased significantly from 595 ± 256 to 2260 ± 1414 mg/day (p ≤0.0001), while maintaining mean plasma Phe levels within treatment range. Four patients no longer required dietary Phe restriction and could discontinue medical food. The majority of patients had at least one BH4-responsive genotype. Conclusion This cohort demonstrates the maximally achievable dietary liberalization which some PKU patients may expect with BH4 therapy. Health benefits are considered to accrue in patients with increased intact protein.
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Affiliation(s)
- Jariya Upadia
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Kea Crivelly
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Grace Noh
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Amy Cunningham
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Caroline Cerminaro
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Yuwen Li
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Meredith Mckoin
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Madeline Chenevert
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Hans C. Andersson
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Zhang C, Zhang P, Yan Y, Zhou B, Wang Y, Tian X, Hao S, Ma P, Zheng L, Zhang Q, Hui L, Wang Y, Cao Z, Ma X. The spectrum of phenylalanine hydroxylase variants and genotype-phenotype correlation in phenylketonuria patients in Gansu, China. Hum Genomics 2023; 17:36. [PMID: 37098607 PMCID: PMC10127316 DOI: 10.1186/s40246-023-00475-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/15/2023] [Indexed: 04/27/2023] Open
Abstract
BACKGROUND Phenylketonuria (PKU) is a common, congenital, autosomal recessive, metabolic disorder caused by Phenylalanine hydroxylase (PAH) variants. METHODS 967 PKU patients from Gansu, China were genotyped by Sanger sequencing, multiplex ligation-dependent probe amplification, and whole exome sequencing. We analyzed the variants of PAH exons, their flanking sequences, and introns. RESULTS The detection of deep intronic variants in PAH gene can significantly improve the genetic diagnostic rate of PKU. The distribution of PAH variants among PKU subtypes may be related to the unique genetic background in Gansu, China. CONCLUSION The identification of PAH hotspot variants will aid the development of large-scale neonatal genetic screening for PKU. The five new PAH variants found in this study further expand the spectrum of PAH variants. Genotype-phenotype correlation analysis may help predict the prognosis of PKU patients and enable precise treatment regimens to be developed.
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Affiliation(s)
- Chuan Zhang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
- National Research Institute for Family Planning , National Human Genetic Resources Center, Beijing, China
| | - Pei Zhang
- Department of Nosocomial Infection Management, Lanzhou University Second Hospital, Lanzhou, China
| | - Yousheng Yan
- Prenatal Diagnostic Center, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Bingbo Zhou
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Yupei Wang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Xinyuan Tian
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Shengju Hao
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Panpan Ma
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Lei Zheng
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Qinghua Zhang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Ling Hui
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Yan Wang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Zongfu Cao
- National Research Institute for Family Planning , National Human Genetic Resources Center, Beijing, China.
| | - Xu Ma
- National Research Institute for Family Planning , National Human Genetic Resources Center, Beijing, China.
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3
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Luo X, Wang R, Sun Y, Qiu W, Lu D, Wang Y, Gong Z, Zhang H, Han L, Liang L, Gu X, Yu Y, Xiao B. Deep Intronic PAH Variants Explain Missing Heritability in Hyperphenylalaninemia. J Mol Diagn 2023; 25:284-294. [PMID: 36849017 DOI: 10.1016/j.jmoldx.2023.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/18/2023] [Accepted: 02/02/2023] [Indexed: 02/27/2023] Open
Abstract
Phenylalanine hydroxylase (PAH) deficiency or phenylketonuria (PKU) is the most common cause of hyperphenylalaninemia (HPA), and approximately 5% of patients remain genetically unsolved. Identifying deep intronic PAH variants may help improve their molecular diagnostic rate. Next-generation sequencing was utilized to detect the whole PAH gene in 96 patients with genetically unsolved HPA from 2013 to 2022. The effects of deep intronic variants on pre-mRNA splicing were investigated by minigene-based assay. The allelic phenotype values of recurrent deep intronic variants were calculated. Twelve deep intronic PAH variants, located in intron 5 (c.509+434C>T), intron 6 (c.706+288T>G, c.706+519T>C, c.706+531T>C, c.706+535G>T, c.706+600A>C, c.706+603T>G, and c.706+608A>C), intron 10 (c.1065+241C>A and c.1065+258C>A), and intron 11 (c.1199+502A>T and c.1199+745T>A) were identified in 80.2% (77/96) patients. Ten of the 12 variants were novel, and they all generated pseudoexons in mRNA, leading to frameshift or lengthened proteins. The most prevalent deep intronic variant was c.1199+502A>T, followed by c.1065+241C>A, c.1065+258C>A, and c.706+531T>C. The metabolic phenotypes of the four variants were assigned as classic PKU, mild HPA, mild HPA, and mild PKU, respectively. The results suggest that deep intronic PAH variants improved the diagnostic rate from 95.3% to 99.3% in the overall patients with HPA. Our data demonstrate the importance of assessing noncoding variants in genetic diseases. Pseudoexon inclusion caused by deep intronic variants could represent a recurrent mechanism.
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Affiliation(s)
- Xiaomei Luo
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Ruifang Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Yu Sun
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Wenjuan Qiu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Deyun Lu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Yu Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Zhuwen Gong
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Huiwen Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Lianshu Han
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Lili Liang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Yongguo Yu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China.
| | - Bing Xiao
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China.
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Zeng B, Lu Q, Chen S, Guan H, Xu X, Zou Y, Wang F, Huang S, Liu Y, Yang B. Screening and mutation analysis of phenylalanine hydroxylase deficiency in newborns from Jiangxi province. Front Genet 2023; 14:1049816. [PMID: 36845377 PMCID: PMC9946975 DOI: 10.3389/fgene.2023.1049816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 01/31/2023] [Indexed: 02/11/2023] Open
Abstract
Background: Phenylalanine hydroxylase deficiency (PAHD) is an autosomal recessive disorder of amino acid metabolism and caused by mutations in the phenylalanine hydroxylase (PAH) gene. Without timely and appropriate dietary management, the disturbance of amino acid metabolism may impair cognitive development and neurophysiological function. Newborn screening (NBS) can aid the early diagnosis of PAHD, which can give accurate therapy to PAHD patients in time. In China, the PAHD incidence and PAH mutation spectrum vary enormously across the provinces. A total of 5,541,627 newborns from Jiangxi province were screened by NBS between 1997 and 2021. Method: One seventy one newborns from Jiangxi province were diagnosed with PAHD. By Sanger sequencing and the multiplex ligation-dependent probe amplification (MLPA) analysis, mutation analysis was performed in 123 PAHD patients. Using an arbitrary values (AV)-based model, we compared the observed phenotype with the predicted phenotype based on the genotype. Results: In this study, we speculated the PAHD incidence of Jiangxi province was about 30.9 per 1,000,000 live births (171/5,541,627). We summarized the PAH mutation spectrum in Jiangxi province for the first time. Two novel variants (c.433G > C, c.706 + 2T > A) were found. The most prevalent variant was c.728G > A (14.1%). The overall prediction rate of the genotype-phenotype was 77.4%. Conclusion: This mutation spectrum is very meaningful to improve the diagnostic rate of PAHD and to increase the accuracy genetic counseling. This study offers data for the genotype-phenotype prediction suitable for Chinese population.
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Affiliation(s)
- Baitao Zeng
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Qing Lu
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Shaohong Chen
- Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Huizhen Guan
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Xiaolan Xu
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Yongyi Zou
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Feng Wang
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Shuhui Huang
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China
| | - Yanqiu Liu
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China,*Correspondence: Yanqiu Liu, ; Bicheng Yang,
| | - Bicheng Yang
- Department of Medical Genetics, Jiangxi Maternal and Child Health Hospital, Nanchang, China,Jiangxi Provincial Key Laboratory of Birth Defect for Prevention and Control, Jiangxi Maternal and Child Health Hospital, Nanchang, China,*Correspondence: Yanqiu Liu, ; Bicheng Yang,
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5
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Song Y, Yin Z, Zhang C, Hao S, Li H, Wang S, Yang X, Li Q, Zhuang D, Zhang X, Cao Z, Ma X. Random forest classifier improving phenylketonuria screening performance in two Chinese populations. Front Mol Biosci 2022; 9:986556. [PMID: 36304929 PMCID: PMC9592754 DOI: 10.3389/fmolb.2022.986556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/26/2022] [Indexed: 11/13/2022] Open
Abstract
Phenylketonuria (PKU) is a genetic disorder with amino acid metabolic defect, which does great harms to the development of newborns and children. Early diagnosis and treatment can effectively prevent the disease progression. Here we developed a PKU screening model using random forest classifier (RFC) to improve PKU screening performance with excellent sensitivity, false positive rate (FPR) and positive predictive value (PPV) in all the validation dataset and two testing Chinese populations. RFC represented outstanding advantages comparing several different classification models based on machine learning and the traditional logistic regression model. RFC is promising to be applied to neonatal PKU screening.
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Affiliation(s)
- Yingnan Song
- National Human Genetic Resources Center, National Research Institute for Family Planning, Beijing, China
- Graduate School of Peking Union Medical College, Beijing, China
| | - Zhe Yin
- National Human Genetic Resources Center, National Research Institute for Family Planning, Beijing, China
| | - Chuan Zhang
- National Human Genetic Resources Center, National Research Institute for Family Planning, Beijing, China
- Graduate School of Peking Union Medical College, Beijing, China
- Gansu Province Medical Genetics Center, Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Shengju Hao
- Gansu Province Medical Genetics Center, Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Haibo Li
- The Central Laboratory of Birth Defects Prevention and Control, Ningbo Women and Children’s Hospital, Ningbo, China
| | - Shifan Wang
- Gansu Province Medical Genetics Center, Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Xiangchun Yang
- The Central Laboratory of Birth Defects Prevention and Control, Ningbo Women and Children’s Hospital, Ningbo, China
| | - Qiong Li
- The Central Laboratory of Birth Defects Prevention and Control, Ningbo Women and Children’s Hospital, Ningbo, China
| | - Danyan Zhuang
- The Central Laboratory of Birth Defects Prevention and Control, Ningbo Women and Children’s Hospital, Ningbo, China
| | - Xinyuan Zhang
- National Human Genetic Resources Center, National Research Institute for Family Planning, Beijing, China
| | - Zongfu Cao
- National Human Genetic Resources Center, National Research Institute for Family Planning, Beijing, China
- *Correspondence: Zongfu Cao, ; Xu Ma,
| | - Xu Ma
- National Human Genetic Resources Center, National Research Institute for Family Planning, Beijing, China
- Graduate School of Peking Union Medical College, Beijing, China
- *Correspondence: Zongfu Cao, ; Xu Ma,
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Elhawary NA, AlJahdali IA, Abumansour IS, Elhawary EN, Gaboon N, Dandini M, Madkhali A, Alosaimi W, Alzahrani A, Aljohani F, Melibary EM, Kensara OA. Genetic etiology and clinical challenges of phenylketonuria. Hum Genomics 2022; 16:22. [PMID: 35854334 PMCID: PMC9295449 DOI: 10.1186/s40246-022-00398-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/08/2022] [Indexed: 02/08/2023] Open
Abstract
This review discusses the epidemiology, pathophysiology, genetic etiology, and management of phenylketonuria (PKU). PKU, an autosomal recessive disease, is an inborn error of phenylalanine (Phe) metabolism caused by pathogenic variants in the phenylalanine hydroxylase (PAH) gene. The prevalence of PKU varies widely among ethnicities and geographic regions, affecting approximately 1 in 24,000 individuals worldwide. Deficiency in the PAH enzyme or, in rare cases, the cofactor tetrahydrobiopterin results in high blood Phe concentrations, causing brain dysfunction. Untreated PKU, also known as PAH deficiency, results in severe and irreversible intellectual disability, epilepsy, behavioral disorders, and clinical features such as acquired microcephaly, seizures, psychological signs, and generalized hypopigmentation of skin (including hair and eyes). Severe phenotypes are classic PKU, and less severe forms of PAH deficiency are moderate PKU, mild PKU, mild hyperphenylalaninaemia (HPA), or benign HPA. Early diagnosis and intervention must start shortly after birth to prevent major cognitive and neurological effects. Dietary treatment, including natural protein restriction and Phe-free supplements, must be used to maintain blood Phe concentrations of 120-360 μmol/L throughout the life span. Additional treatments include the casein glycomacropeptide (GMP), which contains very limited aromatic amino acids and may improve immunological function, and large neutral amino acid (LNAA) supplementation to prevent plasma Phe transport into the brain. The synthetic BH4 analog, sapropterin hydrochloride (i.e., Kuvan®, BioMarin), is another potential treatment that activates residual PAH, thus decreasing Phe concentrations in the blood of PKU patients. Moreover, daily subcutaneous injection of pegylated Phe ammonia-lyase (i.e., pegvaliase; PALYNZIQ®, BioMarin) has promised gene therapy in recent clinical trials, and mRNA approaches are also being studied.
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Affiliation(s)
- Nasser A. Elhawary
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Imad A. AlJahdali
- grid.412832.e0000 0000 9137 6644Department of Community Medicine, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Iman S. Abumansour
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Ezzeldin N. Elhawary
- grid.123047.30000000103590315Faculty of Medicine, MS Genomic Medicine Program, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Nagwa Gaboon
- grid.7269.a0000 0004 0621 1570Department of Clinical Genetics, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Mohammed Dandini
- Department of Laboratory and Blood Bank, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Abdulelah Madkhali
- grid.415254.30000 0004 1790 7311Department of Pathology and Laboratory Medicine, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
| | - Wafaa Alosaimi
- Department of Hematology, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Abdulmajeed Alzahrani
- Department of Laboratory and Blood Bank at Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Fawzia Aljohani
- Department of Pediatric Clinics, Maternity and Children Hospital, King Salman Medical City, Madinah, Saudi Arabia
| | - Ehab M. Melibary
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Osama A. Kensara
- grid.412832.e0000 0000 9137 6644Department of Clinical Nutrition, Faculty of Applied Medical Sciences, Umm Al-Qura University, Jeddah, Saudi Arabia
- Department of Biochemistry, Batterjee Medical College, Jeddah, Saudi Arabia
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7
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Characterization of phenylalanine hydroxylase gene variants and analysis of genotype-phenotype correlation in patients with phenylalanine hydroxylase deficiency from Fujian Province, Southeastern China. Mol Biol Rep 2022; 49:10409-10419. [PMID: 36104584 PMCID: PMC9618490 DOI: 10.1007/s11033-022-07579-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 05/06/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Phenylalanine hydroxylase deficiency (PAHD) is the most prevalent inherited disorder of amino acid metabolism in China. Its complex phenotype includes many variants and genotypes among different populations. METHODS AND RESULTS In this study, we analyzed the phenylalanine hydroxylase gene (PAH) variants in a cohort of 93 PAHD patients from Fujian Province. We also assessed genotype and phenotype correlation in patients with PAHD. A total of 44 different pathogenic variants were identified, including five novel variants. The three most prevalent variants among all patents were c.158G > A, p.(Arg53His) (18.03%), c.721C > T, p.(Arg241Cys) (14.75%), and c.728G > A, p.(Arg243Gln) (7.65%). The frequency of the c.158G > A, p.(Arg53His) variant was highest in patients with mild hyperphenylalaninemia, whereas the frequency of the c.1197A > T, p.(Val399 =) and c.331C > T, p.(Arg111Ter) variants was highest in patients with classic phenylketonuria. The most abundant genotypes observed in PAHD patients were c.[158G > A];[728G > A], c.[158G > A];[442-1G > A], and c.[158G > A];[721C > T]. Comparing allelic phenotype to genotypic phenotype values yielded fairly accurate predictions of phenotype, with an overall consistency rate was 85.71% for PAHD patients. CONCLUSIONS Our study identified a PAH variant spectrum in PAHD patients from Fujian Province, Southeastern China. Quantitative correlation analysis between genotype and phenotype severity is helpful for genetic counseling and management.
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Jin X, Yan Y, Zhang C, Tai Y, An L, Yu X, Zhang L, Hao S, Cao X, Yin C, Ma X. Identification of novel deep intronic PAH gene variants in patients diagnosed with phenylketonuria. Hum Mutat 2021; 43:56-66. [PMID: 34747549 DOI: 10.1002/humu.24292] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 10/21/2021] [Accepted: 10/28/2021] [Indexed: 12/17/2022]
Abstract
Phenylketonuria (PKU) is caused by phenylalanine hydroxylase (PAH) gene variants. Previously, 94.21% of variants were identified using Sanger sequencing and multiplex ligation-dependent probe amplification. To investigate the remaining variants, we performed whole-genome sequencing for four patients with PKU and unknown genotypes to identify deep intronic or structural variants. We identified three novel heterozygous variants (c.706+368T>C, c.1065+241C>A, and c.1199+502A>T) in a deep PAH gene intron. We detected a c.1199+502A>T variant in 60% (6/10) of PKU patients with genetically undetermined PKU. In silico predictions indicated that the three deep variants may impact splice site selection and result in the inclusion of a pseudo-exon. A c.1199+502A>T PAH minigene and reverse transcription PCR (RT-PCR) on blood RNA from a PKU patient with biallelic variants c.1199+502A>T and c.1199G>A confirmed that the c.1199+502A>T variant may strengthen the predicted branch point and leads to the inclusion of a 25-nt pseudo-exon in the PAH mRNA. Reverse transcription polymerase chain reaction (RT-PCR) on the minigene revealed that c.706+368T>C may create an SRSF2 (SC35) binding site via a 313-nt pseudo-exon, whereas c.1065+241C>A may produce an 81-nt pseudo-exon that strengthens the predicted SRSF1 (SF2/ASF) binding site. These results augment current knowledge of PAH genotypes and show that deep intronic analysis of PAH can genetically diagnose PKU.
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Affiliation(s)
- Xiaohua Jin
- National Research Institute for Family Planning, Beijing, China.,National Human Genetic Resources Center, Beijing, China
| | - Yousheng Yan
- Prenatal Diagnostic Center, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Chuan Zhang
- National Research Institute for Family Planning, Beijing, China.,National Human Genetic Resources Center, Beijing, China.,Gansu Province Medical Genetics Center, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Ya Tai
- Department of Obstetrics and Gynecology, Peking University International Hospital, Beijing, China
| | - Lisha An
- National Research Institute for Family Planning, Beijing, China.,National Human Genetic Resources Center, Beijing, China
| | - Xinyou Yu
- Department of Prenatal Diagnosis Center, General Hospital of Ningxia Medical University, Yinchuan, China
| | - Linlin Zhang
- Clinical Lab, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Shengju Hao
- Gansu Province Medical Genetics Center, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Xiaofang Cao
- National Research Institute for Family Planning, Beijing, China.,National Human Genetic Resources Center, Beijing, China
| | - Chenghong Yin
- Prenatal Diagnostic Center, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Xu Ma
- National Research Institute for Family Planning, Beijing, China.,National Human Genetic Resources Center, Beijing, China
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9
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A capillary electrophoresis-based variant hotspot genotyping method for rapid and reliable analysis of the phenylalanine hydroxylase gene in the Chinese Han population. Clin Chim Acta 2021; 523:267-272. [PMID: 34653385 DOI: 10.1016/j.cca.2021.10.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/09/2021] [Accepted: 10/09/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND AND AIMS Hyperphenylalaninemia (HPA) is a common autosomal recessive disorder of phenylalanine metabolism, mainly caused by the deficiency of phenylalanine hydroxylase gene (PAH). A simple, fast, and accurate assay to achieve early diagnosis for children with HPA is required. MATERIALS AND METHODS In the present study, we established a SNaPshot-based assay that allows the simultaneous genotyping of 96 hotspot variants in the PAH gene. First, 18 Chinese HPA patients were analyzed by next generation sequencing (NGS) and SNaPshot in parallel. Then, the SNaPshot assay was performed to analyze the mutational spectrum of the PAH in 4,276 individuals in Eastern China. RESULTS A total of 36 variants in the PAH gene were successfully identified by NGS, while the SNaPshot assay identified 34 PAH variants in these patients. Thus, the SNaPshot assay achieved the sensitivity and specificity of 91.6% and 100.0%, respectively. Furthermore, the carrier rate was approximately 1 in 58 (1.73%) in 4,276 individuals, and c.728G > A was the most common variant. CONCLUSION In summary, SNaPshot can accurately and rapidly detect PAH gene variants at a comparable performance and lower cost as compared with NGS. Our results suggest that SNaPshot may serve as a promising approach for a routine genetic test in clinical practice.
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10
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Zhang Z, Ma D, Wang X, Wang Y, Li Y, Yang P, Sun Y, Jiang T, Xu Z. A joint method for the screening of pharmacological chaperones for phenylalanine hydroxylase. Org Biomol Chem 2021; 19:5827-5835. [PMID: 34113943 DOI: 10.1039/d1ob00638j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phenylalanine hydroxylase (PAH) deficiency (PAHD) is an autosomal recessive disorder that causes severe injury to the nervous system, the treatment of which mainly depends on dietary therapy. The limited treatment options for PAHD are an incentive to develop new methods to identify more efficient therapeutic drugs, such as agonists which could improve PAH activity. In this study, we aimed to establish a rapid and convenient method for the screening and verification of PAH agonists. We compared fluorospectrophotometry and tandem mass spectrometry for detection of enzymatic formation of tyrosine, finding that the latter was a more sensitive method. We optimized immunoprecipitation purification conditions and measurement conditions of PAH activity. The optimal ratio between PAH protein and magnetic beads was 500 μg protein per 20 μL beads, and the optimized conditions for the detection of PAH enzymatic activity included the presence of 75 μM coenzyme ((6R)-l-erythro-5,6,7,8-tetrahydrobiopterin) and 30 min reaction time. Based on virtual screening, we screened ten candidate agonists from the FDA drug library. Three of these (nefopam, fluocinonide, and risperidone) were found to activate the enzyme in a dose-dependent manner (0.1-10 μM) by the joint method. We tested the efficacy of the three agonists on three PAH mutations (p.I65T, p.H107R, and p.D101N) that influence enzyme activity, and found that risperidone could specifically activate D101N-mutated enzyme. In conclusion, we established a joint method that is highly reliable, cost-effective, labor-saving, and time-saving. And we also found a specific agonist for D101N-mutated PAH by this joint method which may assist the development of clinical treatment for PAHD patients with different enzyme deficiencies.
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Affiliation(s)
- Zhilei Zhang
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Dingyuan Ma
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Xin Wang
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Yanyun Wang
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Yahong Li
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Peiyin Yang
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Yun Sun
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Tao Jiang
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
| | - Zhengfeng Xu
- The affiliated Obstetrics and Gynecology Hospital with Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Center of Genetic Medicine, Nanjing 210004, Jiangsu, P.R. China.
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11
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Tao Y, Han D, Shen H, Li X. Spectrum of PAH gene mutations and genotype-phenotype correlation in patients with phenylalanine hydroxylase deficiency from Shanxi province. Brain Dev 2021; 43:220-229. [PMID: 32893076 DOI: 10.1016/j.braindev.2020.08.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/04/2020] [Accepted: 08/18/2020] [Indexed: 01/12/2023]
Abstract
BACKGROUND Phenylalanine hydroxylase deficiency (PAHD) is an autosomal recessive inborn error that affects phenylalanine (Phe) metabolism. It has a complex phenotype with many variants and genotypes among different populations. Shanxi province is a high-prevalence area of PAHD in China. METHODS In this study, eighty-nine PAHD patients were subjected to genetic testing using Sanger sequencing, followed by multiplex ligation-dependent probe amplification analysis (MLPA). Allelic and genotypic phenotype values (APV and GPV, respectively) were used for genotype-based phenotypic prediction. RESULTS Fifty-one types of variants, including three novel forms, were identified. The predominant variant was p.R243Q (22.09%), followed by p.R53H (10.47%), p.EX6-96A > G (9.30%), p.V399V (5.23%) and p.R413P (3.49%). Notably, mild hyperphenylalaninemia (MHP) has a high prevalence in this region (up to 45.76%), and the variant p.R53H was solely observed in patients of MHP. According to the genotype-phenotype prediction, the APV/GPV system was well correlated with the metabolic phenotype of most PAHD patients. CONCLUSION We have systematically constructed the mutational and phenotypic spectrum of PAH in Shanxi province. Hence, this study will help to further understand the genotype-phenotype associations in PAHD patients, and it may offer more reliable genetic counseling and management.
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Affiliation(s)
- Yilun Tao
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China
| | - Dong Han
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China
| | - Huiyi Shen
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China
| | - Xiaoze Li
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China.
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12
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Yan Y, Jin X, Wang X, Zhang C, Zhang Q, Zheng L, Feng X, Hao S, Gao H, Ma X. Screening of PAH Common Mutations in Chinese Phenylketonuria Patients Using iPLEX MALDI-TOF MS. ACS OMEGA 2020; 5:1805-1812. [PMID: 32039316 PMCID: PMC7003239 DOI: 10.1021/acsomega.9b02955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
Phenylketonuria (PKU) is caused by phenylalanine hydroxylase (PAH) gene variants. Previous research has identified some PAH mutation hotspots in Chinese patients with PKU. In this study, we introduce a novel MassArray panel for screening the 29 common PAH gene mutations in Chinese patients using iPLEX MALDI-TOF MS. 105 Patients with PKU and known PAH gene mutations were genotyped using this MassArray panel. All of the 29 mutations screened were detected, and MassArray panel results were consistent with those obtained by Sanger sequencing. Fifty patients newly diagnosed with PKU were recruited in the double-blind experiment. PAH gene variants were detected in these 50 patients using the MassArray panel, and the results were verified with Sanger sequencing and Multiplex Ligation-dependent Probe Amplification (MLPA) methods. Our results show that the mutation detection rate using the MassArray panel with 29 mutations is 74% (95% CI, 65-83%), and the clinical genetic diagnosis rate is 54% (95% CI, 40-68%). This panel can be used as a high throughput, low cost, and rapid method for screening and diagnosing PAH gene mutations. The establishment of this approach provides proof-of-concept for future large-scale PAH mutation carrier screening in areas with high rates of PKU.
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Affiliation(s)
- Yousheng Yan
- National
Research Institute for Family Planning, Beijing 100081, China
- Gansu
Province Medical Genetics Center, Gansu
Provincial Maternity and Child-Care Hospital, Lanzhou 730050, China
- Peking
University International Hospital, Beijing 102206, China
| | - Xiaohua Jin
- National
Research Institute for Family Planning, Beijing 100081, China
| | - Xing Wang
- Gansu
Province Medical Genetics Center, Gansu
Provincial Maternity and Child-Care Hospital, Lanzhou 730050, China
| | - Chuan Zhang
- Gansu
Province Medical Genetics Center, Gansu
Provincial Maternity and Child-Care Hospital, Lanzhou 730050, China
| | - Qinhua Zhang
- Gansu
Province Medical Genetics Center, Gansu
Provincial Maternity and Child-Care Hospital, Lanzhou 730050, China
| | - Lei Zheng
- Gansu
Province Medical Genetics Center, Gansu
Provincial Maternity and Child-Care Hospital, Lanzhou 730050, China
| | - Xuan Feng
- Gansu
Province Medical Genetics Center, Gansu
Provincial Maternity and Child-Care Hospital, Lanzhou 730050, China
| | - Shengju Hao
- Gansu
Province Medical Genetics Center, Gansu
Provincial Maternity and Child-Care Hospital, Lanzhou 730050, China
| | - Huafang Gao
- National
Research Institute for Family Planning, Beijing 100081, China
| | - Xu Ma
- National
Research Institute for Family Planning, Beijing 100081, China
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