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Ma K, Zhang K, Chen D, Wang C, Abdalla M, Zhang H, Tian R, Liu Y, Song L, Zhang X, Liu F, Liu G, Wang D. Real-world evidence: Risdiplam in a patient with spinal muscular atrophy type I with a novel splicing mutation and one SMN2 copy. Hum Mol Genet 2024:ddae052. [PMID: 38520738 DOI: 10.1093/hmg/ddae052] [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: 11/08/2023] [Revised: 03/08/2024] [Accepted: 03/08/2024] [Indexed: 03/25/2024] Open
Abstract
Spinal muscular atrophy (SMA), which results from the deletion or/and mutation in the SMN1 gene, is an autosomal recessive neuromuscular disorder that leads to weakness and muscle atrophy. SMN2 is a paralogous gene of SMN1. SMN2 copy number affects the severity of SMA, but its role in patients treated with disease modifying therapies is unclear. The most appropriate individualized treatment for SMA has not yet been determined. Here, we reported a case of SMA type I with normal breathing and swallowing function. We genetically confirmed that this patient had a compound heterozygous variant: one deleted SMN1 allele and a novel splice mutation c.628-3T>G in the retained allele, with one SMN2 copy. Patient-derived sequencing of 4 SMN1 cDNA clones showed that this intronic single transversion mutation results in an alternative exon (e)5 3' splice site, which leads to an additional 2 nucleotides (AG) at the 5' end of e5, thereby explaining why the patient with only one copy of SMN2 had a mild clinical phenotype. Additionally, a minigene assay of wild type and mutant SMN1 in HEK293T cells also demonstrated that this transversion mutation induced e5 skipping. Considering treatment cost and goals of avoiding pain caused by injections and starting treatment as early as possible, risdiplam was prescribed for this patient. However, the patient showed remarkable clinical improvements after treatment with risdiplam for 7 months despite carrying only one copy of SMN2. This study is the first report on the treatment of risdiplam in a patient with one SMN2 copy in a real-world setting. These findings expand the mutation spectrum of SMA and provide accurate genetic counseling information, as well as clarify the molecular mechanism of careful genotype-phenotype correlation of the patient.
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Affiliation(s)
- Kai Ma
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
- Department of neurology, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Kaihui Zhang
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Defang Chen
- The Office of operation management committee, Central Hospital Affiliated to Shandong First Medical University, Jiefang road NO. 105, Jinan, SD 250022, PR China
| | - Chuan Wang
- Science, Education and Foreign Affairs Section, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Mohnad Abdalla
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Haozheng Zhang
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Rujin Tian
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Yang Liu
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
- Ophthalmology department, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Li Song
- Pediatric Hematology and Oncology, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Xinyi Zhang
- Intensive Care Unit, The Second People's Hospital of Shandong Province, Duanxing west road NO. 4, Jinan, SD 250022, PR China
| | - Fangfang Liu
- Department of Ultrasound, Central Hospital Affiliated to Shandong First Medical University, Jiefang road NO. 105, Jinan, SD 250022, PR China
| | - Guohua Liu
- Ophthalmology department, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
| | - Dong Wang
- Pediatric Research Institute, Children's Hospital Affiliated to Shandong University, Jingshi road NO. 23976, Jinan, SD 250022, PR China
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Çıkı K, Yıldız Y, Kahraman AB, Özgül RK, Coşkun T, Dursun A, Tokatlı A, Sivri S. Predictors of eventual requirement of phenylalanine-restricted diet in young infants with phenylalanine hydroxylase deficiency initially managed with sapropterin monotherapy. Mol Genet Metab 2023; 140:107706. [PMID: 37837865 DOI: 10.1016/j.ymgme.2023.107706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 10/02/2023] [Accepted: 10/02/2023] [Indexed: 10/16/2023]
Abstract
BACKGROUND Phenylalanine (Phe)-restricted diet is associated with lower quality of life for patients with phenylketonuria (PKU), and a concern for caregivers of recently-diagnosed infants. Sapropterin is an oral drug used as an alternative or adjunct to dietary treatment. We have observed that some of the young infants initially managed successfully with sapropterin monotherapy have required dietary treatment in long-term follow-up. We aimed to determine the baseline factors associated with future initiation of dietary treatment in these patients. METHODS Data were obtained retrospectively from the medical records of 80 PKU patients started on sapropterin monotherapy before 3 months of age between 2011 and 2021. RESULTS The patients were followed for a median of 3.9 years (Q1-Q3: 2.5-5.75 years). Sapropterin was tapered down and discontinued in 5 patients (6.3%) as their Phe levels remained below 360 μmol/L without treatment. Sapropterin monotherapy was sufficient in 62 patients (77.5%), while 13 (16.2%) required dietary treatment. Phe and tyrosine (Tyr) levels, and Phe:Tyr ratios differed significantly among the patients maintained on sapropterin monotherapy and those started on dietary treatment, but the Phe:Tyr ratio at diagnosis was the most important independent baseline variable (OR: 1.61, 95% CI: 1.15-2.27, p = 0.006), with Phe:Tyr ratio at diagnosis >5.25 associated with dietary treatment (sensitivity: 90.0%, specificity: 81.8%). Genotypic phenotype value (GPV), unavailable at baseline, was also associated with dietary treatment (median GPV 9.2 vs. 3.8, p = 0.006), but some genotypes were not specific to the final treatment modality. DISCUSSION We propose that the Phe:Tyr ratio at diagnosis is an important indicator to predict dietary requirement in young infants initially managed with sapropterin monotherapy.
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Affiliation(s)
- Kısmet Çıkı
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Yılmaz Yıldız
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ayça Burcu Kahraman
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - R Köksal Özgül
- Hacettepe University Institute of Child Health, Ankara, Turkey.
| | - Turgay Coşkun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ali Dursun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ayşegül Tokatlı
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Serap Sivri
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
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3
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Fishchuk L, Rossokha Z, Olkhovich N, Pichkur N, Popova O, Medvedieva N, Vershyhora V, Dubitska O, Shkurko T, Popovych L, Bondar O, Morozuk I, Onyshchenko S, Yevtushok L, Tsizh O, Bryl I, Tul O, Kalynka S, Zinkina I, Matviiuk S, Riabova Y, Gorovenko N. The analysis of using a panel of the most common variants in the PAH gene for the newborn screening in Ukraine. Mol Genet Metab Rep 2022; 32:100907. [PMID: 36046396 PMCID: PMC9421484 DOI: 10.1016/j.ymgmr.2022.100907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/26/2022] [Accepted: 07/26/2022] [Indexed: 11/25/2022] Open
Abstract
Phenylketonuria (PKU) is hyperphenylalaninemia that develops due to a deficiency of the phenylalanine hydroxylase enzyme (PAH). Identification of variants in the PAH gene is necessary for verification of the diagnosis, choice of treatment tactics, detection of heterozygous carriers. The aim of the study was to analyze the effectiveness of identification of selected pathological variants in the PAH gene during the newborn screening program. This study relied on the results of the examination of 257 patients (138 boys and 119 girls) with hyperphenylalaninemia from different regions of Ukraine. Genotyping was performed on nine pathogenic variants in PAH gene: I65T, R261Q, G272*, R252W, R261*, R408W, IVS12 + 1G > A, Y414C, IVS10-11G > A. According to the results of the study, variants R408W (AF = 52.7%), R252W (AF = 3.5%) and Y414C (AF = 1.8%) were the most common. More than half of the examined patients (51.7%) had a compound genotype with a major variant of R408W in one allele. Approximately a quarter of the examined patients (26.8%) had the R408W/R408W genotype. In 12.1% of patients, the applied panel of variants of the РАН gene did not allow us to identify the pathogenic variant in any allele. We conclude that the selected panel allowed us to identify the presence of variants in 87.9% of patients with PKU. The panel of genetic testing in the PAH gene for the newborns that we used for the study allows accurate prediction of some phenotypes for therapy planning. But in-depth analysis of pathological gene variants may be necessary for unclear and difficult cases of the disease, and for genetic counseling of patients families.
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Affiliation(s)
- Liliya Fishchuk
- SI "Reference-centre for molecular diagnostic of Public Health Ministry of Ukraine", Kyiv, Ukraine.,Institute of Genetic and Regenerative Medicine NAMS of Ukraine, Kyiv, Ukraine
| | - Zoia Rossokha
- SI "Reference-centre for molecular diagnostic of Public Health Ministry of Ukraine", Kyiv, Ukraine
| | - Natalia Olkhovich
- The National Children's Specialised Hospital "OHMATDYT", Kyiv, Ukraine
| | - Nataliia Pichkur
- The National Children's Specialised Hospital "OHMATDYT", Kyiv, Ukraine
| | - Olena Popova
- SI "Reference-centre for molecular diagnostic of Public Health Ministry of Ukraine", Kyiv, Ukraine
| | - Nataliia Medvedieva
- SI "Reference-centre for molecular diagnostic of Public Health Ministry of Ukraine", Kyiv, Ukraine
| | - Viktoriia Vershyhora
- SI "Reference-centre for molecular diagnostic of Public Health Ministry of Ukraine", Kyiv, Ukraine
| | - Olha Dubitska
- SI "Reference-centre for molecular diagnostic of Public Health Ministry of Ukraine", Kyiv, Ukraine
| | - Tetiana Shkurko
- The National Children's Specialised Hospital "OHMATDYT", Kyiv, Ukraine
| | | | - Olga Bondar
- Vinnitsa Regional Clinical Hospital, Vinnitsa, Ukraine
| | - Irina Morozuk
- Vinnitsa Regional Clinical Hospital, Vinnitsa, Ukraine
| | | | | | - Oksana Tsizh
- Rivne Regional Medical Diagnostic Center, Rivne, Ukraine
| | - Iryna Bryl
- ME "Regional Clinical Hospital for Rehabilitation and Diagnostics with Regional Centers for Family Planning and Human Reproduction, Medical Genetics", Poltava, Ukraine
| | - Olena Tul
- ME "Regional Clinical Hospital for Rehabilitation and Diagnostics with Regional Centers for Family Planning and Human Reproduction, Medical Genetics", Poltava, Ukraine
| | - Svitlana Kalynka
- Volyn Regional Children's Territorial Medical Center, Lutsk, Ukraine
| | - Iryna Zinkina
- Mykolaiv Regional Pediatric Hospital, Mykolaiv, Ukraine
| | | | | | - Nataliia Gorovenko
- Institute of Genetic and Regenerative Medicine NAMS of Ukraine, Kyiv, Ukraine.,Shupyk National Healthcare University of Ukraine, Kyiv, Ukraine
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4
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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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5
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Yan Y, Zhang C, Jin X, Zhang Q, Zheng L, Feng X, Hao S, Gao H, Ma X. Mutation spectrum of PAH gene in phenylketonuria patients in Northwest China: identification of twenty novel variants. Metab Brain Dis 2019; 34:733-745. [PMID: 30747360 DOI: 10.1007/s11011-019-0387-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 01/20/2019] [Indexed: 10/27/2022]
Abstract
This study was performed to analyze the mutational spectrum of the phenylalanine hydroxylase (PAH) gene in phenylketonuria (PKU) patients in Northwest China, to identify mutational hot spots, and to determine the correlation between variants and clinical phenotypes of PKU. A large cohort of 475 PKU families in Northwest China was enrolled to analyze PAH gene variants using Sanger sequencing, Multiplex ligation-dependent probe amplification (MLPA), and gap-PCR. Bioinformatics software was used to predict the pathogenicity of novel variants and analyze the correlations between PAH gene variants and phenotypes of PKU patients. A total of 895 variants were detected in the 950 alleles of 475 patients with PKU (detection rate: 94.21%), 20 of which were novel variants. Other 108, previously known variants, were also identified, with the three most frequent variants being p.Arg243Gln (14.00%), c.611A > G (5.58%), and p.Tyr356* (4.95%). Seven different large deletion/duplication variants were identified by the MLPA method, including the large deletion c.-4163_-406del3758 with high frequency. A correlation analysis between patient phenotype and gene variant frequency showed that p.Arg53His and p.Gln419Arg were correlated with mild hyperphenylalaninemia (MHP). In conclusion, the mutational spectrum underlying PKU in Northwest China was established for the first time. Functional analysis of 20 novel PAH gene variants enriched the PAH gene mutational spectrum. Correlation analysis between variants frequencies in compound heterozygous patients and phenotype severity is helpful for phenotypic prediction.
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Affiliation(s)
- Yousheng Yan
- Graduate School of Peking Union Medical College, Beijing, 100730, China
- National Research Institute for Health and Family Planning, No. 12 Dahuisi Road, Beijing, 100081, China
- Gansu Province Medical Genetics Center, Gansu Province Maternal and Child Health Care Hospital, Lanzhou, 730050, China
| | - Chuan Zhang
- Gansu Province Medical Genetics Center, Gansu Province Maternal and Child Health Care Hospital, Lanzhou, 730050, China
| | - Xiaohua Jin
- Graduate School of Peking Union Medical College, Beijing, 100730, China
- National Research Institute for Health and Family Planning, No. 12 Dahuisi Road, Beijing, 100081, China
| | - Qinhua Zhang
- Gansu Province Medical Genetics Center, Gansu Province Maternal and Child Health Care Hospital, Lanzhou, 730050, China
| | - Lei Zheng
- Gansu Province Medical Genetics Center, Gansu Province Maternal and Child Health Care Hospital, Lanzhou, 730050, China
| | - Xuan Feng
- Gansu Province Medical Genetics Center, Gansu Province Maternal and Child Health Care Hospital, Lanzhou, 730050, China
| | - Shengju Hao
- Gansu Province Medical Genetics Center, Gansu Province Maternal and Child Health Care Hospital, Lanzhou, 730050, China
| | - Huafang Gao
- Graduate School of Peking Union Medical College, Beijing, 100730, China.
- National Research Institute for Health and Family Planning, No. 12 Dahuisi Road, Beijing, 100081, China.
| | - Xu Ma
- Graduate School of Peking Union Medical College, Beijing, 100730, China.
- National Research Institute for Health and Family Planning, No. 12 Dahuisi Road, Beijing, 100081, China.
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Genotypes of 2579 patients with phenylketonuria reveal a high rate of BH4 non-responders in Russia. PLoS One 2019; 14:e0211048. [PMID: 30668579 PMCID: PMC6342299 DOI: 10.1371/journal.pone.0211048] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 12/30/2018] [Indexed: 12/12/2022] Open
Abstract
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.
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7
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Three novel variants (p.Glu178Lys, p.Val245Met, p.Ser250Phe) of the phenylalanine hydroxylase (PAH) gene impair protein expression and function in vitro. Gene 2018; 668:135-139. [PMID: 29653233 DOI: 10.1016/j.gene.2018.03.078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 03/10/2018] [Accepted: 03/26/2018] [Indexed: 11/21/2022]
Abstract
Phenylketonuria (PKU) is the most common inherited metabolic disease, an autosomal recessive disorder affecting >10,000 newborns each year globally. It can be caused by over 1000 different naturally occurring mutations in the phenylalanine hydroxylase (PAH) gene. We analyzed three novel naturally occurring PAH gene variants: p.Glu178Lys (c.532G>A), p.Val245Met (c.733G>A) and p.Ser250Phe (c.749C>T). The mutant effect on the PAH enzyme structure and function was predicted by bioinformatics software. Vectors expressing the corresponding PAH variants were generated for expression in E. coli and in HEK293T cells. The RNA expression of the three PAH variants was measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR). The mutant PAH protein levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), western blot and enzyme-linked immunosorbent assay (ELISA). All three variants were predicted to be pathogenic by bioinformatics analysis. The transcription of the three PAH variants was similar to the wild type PAH gene in HEK293T cells. In contrast, the levels of mutant PAH proteins decreased significantly compared to the wild type control, in both E. coli and HEK293T cells. Our results indicate that the three novel PAH gene variants (p.Glu178Lys, p.Val245Met, p.Ser250Phe) impair PAH protein expression and function in prokaryotic and eukaryotic cells.
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8
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Molecular Analysis of PKU-Associated PAH Mutations: A Fast and Simple Genotyping Test. Methods Protoc 2018; 1:mps1030030. [PMID: 31164572 PMCID: PMC6481045 DOI: 10.3390/mps1030030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/06/2018] [Accepted: 08/06/2018] [Indexed: 11/16/2022] Open
Abstract
Neonatal screening for phenylketonuria (PKU, OMIM: 261600) was introduced at the end of the 1960s. We developed a rapid and simple molecular test for the most frequent phenylalanine hydroxylase (PAH, Gene ID: 5053) mutations. Using this method to detect the 18 most frequent mutations, it is possible to achieve a 75% detection rate in Italian population. The variants selected also reach a high detection rate in other populations, for example, 70% in southern Germany, 68% in western Germany, 76% in Denmark, 68% in Sweden, 63% in Poland, and 60% in Bulgaria. We successfully applied this confirmation test in neonatal screening for hyperphenylalaninemias using dried blood spots and obtained the genotype in approximately 48 h. The method was found to be suitable as second tier test in neonatal screening for hyperphenylalaninemias in neonates with a positive screening test. This test can also be useful for carrier screening because it can bypass the entire coding sequence and intron–exon boundaries sequencing, thereby overcoming the questions that this approach implies, such as new variant interpretations.
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9
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Li N, He C, Li J, Tao J, Liu Z, Zhang C, Yuan Y, Jiang H, Zhu J, Deng Y, Guo Y, Li Q, Yu P, Wang Y. Analysis of the genotype-phenotype correlation in patients with phenylketonuria in mainland China. Sci Rep 2018; 8:11251. [PMID: 30050108 PMCID: PMC6062512 DOI: 10.1038/s41598-018-29640-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 07/13/2018] [Indexed: 11/22/2022] Open
Abstract
Mutations in the gene encoding phenylalanine hydroxylase (PAH) are associated with various degrees of phenylketonuria (PKU). The aim of our study was to define the genotype-phenotype correlations of mutations in the PAH gene that cause phenylketonuria (PKU) among the Chinese mainland population. Mutations in the PAH gene were analysed by next-generation sequencing, and a genotype-phenotype correlation analysis was performed in 1079 patients. Fifteen “null + null” genotypes, including four homoallelic and eleven heteroallelic genotypes, were clearly associated with classic PKU. Five functionally hemizygous (p.E280K, p.R252Q, p.E56D, p.S310F and p.T372R) and four compound heterozygous (p.T278I/p.S359L, p.R408W/p.R243Q, p.F161S/p.R243Q and p.F161S/p.R413P) genotypes were clearly associated with classic PKU. Ten functionally hemizygous genotypes, p.G257V, p.R158W, p.L255S, p.G247V, p.F161S, p.R158Q, p.V388M, p.I65T, p.I324N and p.R400K, were frequently associated with classic PKU. Three functionally hemizygous genotypes, p.P147L, p.I95del and p.F331S, and four compound heterozygous genotypes, p.G257V/p.R408Q, p.A434D/p.R413P, p.R243Q/p.A47E and p.R241C/p.G239D, were consistently correlated with mild PKU. Three functionally hemizygous genotypes, p.H107R, p.Q419R and p.F392I, and nine compound heterozygous genotypes (p.G312V/p.R241C, p.R243Q/p.V230I, p.R243Q/p.A403V, p.R243Q/p.Q419R, p.R243Q/p.R53H, p.R243Q/p.H107R, p.R241C/p.R408Q, p.R241C/p.H220P and p.R53H/p.R400K) were consistent with mild hyperphenylalaninaemia (MHP). Our study provides further support for the hypothesis that the PAH genotype is the main factor that determines the phenotype of PKU.
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Affiliation(s)
- Nana Li
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Chunhua He
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Jing Li
- Laboratory of Translational Medicine, Chinese PLA General Hospital, Beijing, China
| | - Jing Tao
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Zhen Liu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Chunyan Zhang
- Laboratory of Translational Medicine, Chinese PLA General Hospital, Beijing, China
| | - Yuan Yuan
- Tianjin Medical Laboratory, BGI-Tianjin, BGI-Shenzhen, Tianjin, 300308, China
| | - Hui Jiang
- BGI-Shenzhen, Shenzhen, 518103, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, 518120, China
| | - Jun Zhu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Ying Deng
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Yixiong Guo
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Qintong Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Ping Yu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China. .,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China.
| | - Yanping Wang
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China. .,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China.
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10
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Vieira Neto E, Laranjeira F, Quelhas D, Ribeiro I, Seabra A, Mineiro N, d. M. Carvalho L, Lacerda L, G. Ribeiro M. Mutation analysis of the PAH gene in phenylketonuria patients from Rio de Janeiro, Southeast Brazil. Mol Genet Genomic Med 2018; 6:575-591. [PMID: 29749107 PMCID: PMC6081236 DOI: 10.1002/mgg3.408] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 03/29/2018] [Accepted: 04/06/2018] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Phenylketonuria (PKU) is an autosomal recessive disease resulting from mutations in the PAH gene. Most of the patients are compound heterozygotes, and genotype is a major factor in determining the phenotypic variability of PKU. More than 1,000 variants have been described in the PAH gene. Rio de Janeiro's population has a predominance of Iberian, followed by African and Amerindian ancestries. It is expected that most PKU variants in this Brazilian state have originated in the Iberian Peninsula. However, rare European, African or pathogenic variants that are characteristic of the admixed population of the state might also be found. METHODS A total of 102 patients were included in this study. Genomic DNA was isolated from dried blood spots. Sanger sequencing was used for PAH gene variant identification. Deletions and duplications were also screened using MLPA analysis. Haplotypes were also determined. RESULTS Nine (8.8%) homozygous and 93 (91.2%) compound heterozygous patients were found. The spectrum included 37 causative mutations. Missense, nonsense, and splicing pathogenic variants corresponded to 63.7%, 2.9%, and 22.6% of the mutant alleles, respectively. Large (1.5%), and small deletions, inframe (5.4%) and with frameshift (3.9%), comprised the remainder. The most frequent pathogenic variants were: p.V388M (12.7%), p.R261Q (11.8%), IVS10-11G>A (10.3%), IVS2+5G>C (6.4%), p.S349P (6.4%), p.R252W (5.4%), p.I65T (4.4%), p.T323del (4.4%), and p.P281L (3.4%). One novel variant was detected: c.934G>T (p.G312C) [rs763115697]. CONCLUSION The three most frequent pathogenic variants in our study (34.8% of the alleles) were also the most common in other Brazilian states, Portugal, and Spain (p.V388M, p.R261Q, IVS10-11G>A), corroborating that the Iberian Peninsula is the major source of PAH mutations in Rio de Janeiro. Pathogenic variants that have other geographical origins, such IVS2+5G>C, p.G352Vfs*48, and IVS12+1G>A were also detected. Genetic drift and founder effect may have also played a role in the mutation spectrum we observed.
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Affiliation(s)
- Eduardo Vieira Neto
- Gerência de Monitoramento AssistencialAgência Nacional de Saúde SuplementarRio de JaneiroBrazil
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
| | - Francisco Laranjeira
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Dulce Quelhas
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Isaura Ribeiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Alexandre Seabra
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Nicole Mineiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Lilian d. M. Carvalho
- Serviço de MetabologiaInstituto de Diabetes e Endocrinologia Luiz CapriglioneRio de JaneiroBrazil
| | - Lúcia Lacerda
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Márcia G. Ribeiro
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
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11
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Zhang Z, Gao JJ, Feng Y, Zhu LL, Yan H, Shi XF, Chang AM, Shi Y, Wang P. Mutational spectrum of the phenylalanine hydroxylase gene in patients with phenylketonuria in the central region of China. Scand J Clin Lab Invest 2018; 78:211-218. [PMID: 29390883 DOI: 10.1080/00365513.2018.1434898] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 01/23/2018] [Accepted: 01/28/2018] [Indexed: 01/15/2023]
Abstract
Phenylketonuria (PKU, OMIM 261600) caused by phenylalanine hydroxylase (PAH) deficiency is an autosomal recessive disease that is characterized by abnormalities of phenylalanine metabolism. In this study, a total of 77 patients, originating from the central region of China and who were diagnosed with PAH deficiency at the third affiliated hospital of Zhengzhou University, were enrolled in this study. The 13 exons and 12 flanking introns of the PAH gene were analyzed by Sanger sequencing and next generation sequencing. The sequencing data were aligned to the hg19, PAHvdb and HGMD databases to characterize the genotypes of PKU patients, and genotype-phenotype correlations and BH4 responsiveness predictions were performed using BIOPKUdb. In total, 149 alleles were characterized among the 154 PKU alleles. These mutations were located in exons 2-13, and intron 12 of the PAH gene, with a relative frequency of ≥5%, for EX6-96A>G, p.R241C, p.R243Q, p.V399V and p.R53H. Additionally, a novel variant, p.D84G, was identified. The genotype correlated with clinical symptoms in 33.3-100% of the cases, depending on the disease severity, and BH4 responsiveness predictions show that only five patients with MHP-PKU and one patient with Mild-PKU were predicted to be BH4 responsive. In conclusion, we have characterized the mutational spectrum of PAH in the central region of China and have identified a novel mutation. The hotspot mutation information might be useful for screening, diagnosis and treatment of PKU.
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Affiliation(s)
- Zhan Zhang
- a The Third Affiliated Hospital of Zhengzhou University , Zhengzhou , China
- b Shangqiu Medical College , Shangqiu , China
| | - Jun-Jun Gao
- a The Third Affiliated Hospital of Zhengzhou University , Zhengzhou , China
| | - Yang Feng
- a The Third Affiliated Hospital of Zhengzhou University , Zhengzhou , China
| | - Lin-Lin Zhu
- c School of Laboratory Medicine , Xinxiang Medical University , Xinxiang , China
| | - Huan Yan
- a The Third Affiliated Hospital of Zhengzhou University , Zhengzhou , China
| | - Xu-Feng Shi
- d Department of Obstetrics , Henan Province People's Hospital , Zhengzhou , China
| | - Ai-Min Chang
- a The Third Affiliated Hospital of Zhengzhou University , Zhengzhou , China
| | - Ying Shi
- a The Third Affiliated Hospital of Zhengzhou University , Zhengzhou , China
| | - Ping Wang
- a The Third Affiliated Hospital of Zhengzhou University , Zhengzhou , China
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12
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Choi R, Lee J, Park HD, Park JE, Kim YH, Ki CS, Lee SY, Song J, Kim JW, Lee DH. Reassessing the significance of the PAH c.158G>A (p.Arg53His) variant in patients with hyperphenylalaninemia. J Pediatr Endocrinol Metab 2017; 30:1211-1218. [PMID: 29032371 DOI: 10.1515/jpem-2017-0158] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 08/21/2017] [Indexed: 11/15/2022]
Abstract
BACKGROUND The accurate interpretation of sequence variation is critical for successful molecular diagnoses. It is also fundamental to the accurate diagnosis and treatment of phenylketonuria (PKU). This study aims to evaluate the significance of the c.158G>A (p.Arg53His) variant in the PAH gene, which was previously reported to be a pathogenic mutation that results in decreased phenylalanine hydroxylase enzyme activity in hyperphenylalaninemia (HPA) patients. METHODS Seven unrelated Korean patients with HPA genotyped with the c.158G>A variant were included in this study. The variant c.158G>A was classified by the standards and guidelines for the interpretation of sequence variants by the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. RESULTS By both directly collecting genetic data and comprehensively reviewing the existing literature, we found that this variant is more appropriately classified as "Likely benign" rather than pathogenic. The allele's frequency is 2.57% in the general Korean population, which was greater than expected for phenylketonuria. This variant was observed to be homozygous in healthy subjects and was also observed in cis with other pathogenic variants. It is common in East Asian populations (especially in Koreans) compared to Western populations. There is a possibility that it causes decreased enzyme activity without leading to the full pathology of phenylketonuria. CONCLUSIONS This study expands our understanding of the consequences of variation in PAH and its relationship to HPA.
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13
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Wang ZW, Jiang SW, Zhou BC. PAH mutation spectrum and correlation with PKU manifestation in north Jiangsu province population. Kaohsiung J Med Sci 2017; 34:89-94. [PMID: 29413232 DOI: 10.1016/j.kjms.2017.09.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/08/2017] [Accepted: 09/15/2017] [Indexed: 01/16/2023] Open
Abstract
Phenylketonuria (PKU) is a common autosomal recessive disorder of phenylalanine metabolism and mainly results a deficiency of phenylalanine hydroxylase gene (PAH). The incidence of various PAH mutations have race and ethnicity differences. We report a spectrum of PAH mutations complied from 35 PKU children who are all Chinese Han population from north Jiangsu in this study. All 13 exons and their flanking intron sequences of PAH were determined by Ion Torrent PGM™ sequencing. The relationship of genotype and phenotype was analyzed based on the sum of the arbitrary value (AV) values of the two alleles. We identified 61 mutations, with a frequency of 87.14%, among 70 alleles of 35 patients. The most prevalent mutations were R243Q (26.23%), R241C (9.84%) and V399V (8.20%). Furthermore, the consistency between prediction of the biochemical phenotype and the observed phenotype was 81.25%, with the highest consistency observed in classic PKU (87.50%). A significant correlation was found between pretreatment levels of phenylalanine and AV sum (r = -0.87, P < 0.05). Finally, our study constructs PAH mutation spectrum by next generation sequencing (NGS), and reveals that the PAH genotypes and biochemical phenotypes were significantly correlated. These offers facilitate the provision of appropriate genetic counseling for PKU patients.
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Affiliation(s)
- Zhen-Wen Wang
- Department of Medical Laboratory, Lianyungang Maternal and Child Health Hospital, Lianyungang, Jiangsu, China
| | - Shi-Wen Jiang
- Department of Biomedical Science, Mercer University School of Medicine, Macon, GA, USA
| | - Bao-Cheng Zhou
- Department of Medical Laboratory, Lianyungang Maternal and Child Health Hospital, Lianyungang, Jiangsu, China.
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14
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Zhu T, Ye J, Han L, Qiu W, Zhang H, Liang L, Gu X. The Predictive Value of Genetic Analyses in the Diagnosis of Tetrahydrobiopterin (BH4)-Responsiveness in Chinese Phenylalanine Hydroxylase Deficiency Patients. Sci Rep 2017; 7:6762. [PMID: 28754886 PMCID: PMC5533732 DOI: 10.1038/s41598-017-06462-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 06/13/2017] [Indexed: 11/23/2022] Open
Abstract
Molecular characterization of PAH deficiency has been proven essential in establishing treatment options. We examine the diagnostic accuracy of two genetic assays to predict BH4 responsiveness: to determine whether the AV sum test or mutation-status assessment test can obviate the need for BH4 loading in Chinese patients. The overall predicted response in 346 patients was 31.65% by the AV sum test and 25.43% by the other assay; both percentages were lower than 51.06% derived from loading results in 94 patients. Responders were compound heterozygotes with definite BH4 responsive mutations, while non-responders had null/null ones; some consistently with specific mutations and genotypes. The sensitivity and specificity of the assays were 81.1% and 92.5% for the AV sum, and 82.9%, 97.3% for the other. An AV sum cutoff >2 has a positive predictive value (PPV) of 90.9%, while the presence of at least one BH4 responsive mutation has a PPV of 97.1%. The two approaches showed good concordance. Our data confirmed that the mutation-status assessment has a higher diagnostic accuracy in predicting response for Chinese patients than the AV sum test. BH4-responsiveness may be predicted or excluded from patients' molecular characteristics to some extent, thus some patients may avoid the initial loading.
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Affiliation(s)
- Tianwen Zhu
- Department of Neonatal Medicine, Xin-Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jun Ye
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lianshu Han
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wenjuan Qiu
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huiwen Zhang
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lili Liang
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xuefan Gu
- Department of Endocrinology and Genetic Metabolism, Xin-Hua Hospital, Shanghai Institute of Pediatric Research Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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15
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Gundorova P, Stepanova AA, Bushueva TV, Belyashova EY, Zinchenko RA, Amelina SS, Kutsev SI, Polyakov AV. Genotyping of patients with phenylketonuria from different regions of Russia for determining BH4 responsiveness. RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417060060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Gundorova P, Stepanova AA, Makaov AK, Zinchenko RA, Abaykhanova ZM, Polyakov AV. Mutation spectrum of the PAH gene in phenylketonuria patients in the Karachay-Cherkess Republic (Russia). RUSS J GENET+ 2016. [DOI: 10.1134/s1022795416110041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Analysis of EX5del4232ins268 and EX5del955 PAH gene mutations in Ukrainian patients with phenylketonuria. Genes Dis 2016; 4:108-110. [PMID: 30258912 PMCID: PMC6136599 DOI: 10.1016/j.gendis.2016.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/19/2016] [Indexed: 12/04/2022] Open
Abstract
Phenylketonuria (PKU) is an autosomal recessive metabolic disorder caused by deficiency of phenylalanine hydroxylase (PAH). The major molecular defects causing PKU are missense mutations of PAH gene. Large deletions of exon 5 (EX5del955 and EX5del4232ins) were first reported by the Czech study and were later found also in the Polish, Slovak, Slovenian and Italian PKU-patients. These observations demonstrate the existence of a common subset of this mutation predominantly among Central European populations of Slavic descent. That is why we suggest that EX5del1955 and EX5del4232ins268 mutations might be frequent causes of PKU in Ukrainian patients. EX5del955 and EX5del4232ins268 mutations were analyzed in 106 unrelated PKU patients negative for PAH gene mutations on one or both alleles from our previous analysis. The simultaneous detection of EX5del4232ins268 and EX5del955 mutations was performed by PCR amplification of mutant alleles. EX5del955 mutation was not detected in the Ukrainian patients. This relative alleles frequency of EX5del4232ins268 mutation in the Ukrainian PKU population was determined as 1,66%. Our findings can be the one more evidence of Central European Slavic origin of EX5del4232ins268 mutation, suggested previously. This finding is important for the improvement of DNA diagnosis necessary for the management of PKU patients from Ukraine.
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18
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Klaassen K, Stankovic B, Kotur N, Djordjevic M, Zukic B, Nikcevic G, Ugrin M, Spasovski V, Srzentic S, Pavlovic S, Stojiljkovic M. New PAH gene promoter KLF1 and 3'-region C/EBPalpha motifs influence transcription in vitro. J Appl Genet 2016; 58:79-85. [PMID: 27447460 DOI: 10.1007/s13353-016-0359-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/01/2016] [Accepted: 06/30/2016] [Indexed: 11/28/2022]
Abstract
Phenylketonuria (PKU) is a metabolic disease caused by mutations in the phenylalanine hydroxylase (PAH) gene. Although the PAH genotype remains the main determinant of PKU phenotype severity, genotype-phenotype inconsistencies have been reported. In this study, we focused on unanalysed sequences in non-coding PAH gene regions to assess their possible influence on the PKU phenotype. We transiently transfected HepG2 cells with various chloramphenicol acetyl transferase (CAT) reporter constructs which included PAH gene non-coding regions. Selected non-coding regions were indicated by in silico prediction to contain transcription factor binding sites. Furthermore, electrophoretic mobility shift assay (EMSA) and supershift assays were performed to identify which transcriptional factors were engaged in the interaction. We found novel KLF1 motif in the PAH promoter, which decreases CAT activity by 50 % in comparison to basal transcription in vitro. The cytosine at the c.-170 promoter position creates an additional binding site for the protein complex involving KLF1 transcription factor. Moreover, we assessed for the first time the role of a multivariant variable number tandem repeat (VNTR) region located in the 3'-region of the PAH gene. We found that the VNTR3, VNTR7 and VNTR8 constructs had approximately 60 % of CAT activity. The regulation is mediated by the C/EBPalpha transcription factor, present in protein complex binding to VNTR3. Our study highlighted two novel promoter KLF1 and 3'-region C/EBPalpha motifs in the PAH gene which decrease transcription in vitro and, thus, could be considered as PAH expression modifiers. New transcription motifs in non-coding regions will contribute to better understanding of the PKU phenotype complexity and may become important for the optimisation of PKU treatment.
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Affiliation(s)
- Kristel Klaassen
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Biljana Stankovic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Nikola Kotur
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Maja Djordjevic
- Mother and Child Health Care Institute of Serbia "Dr Vukan Cupic", School of Medicine, University of Belgrade, Radoja Dakića 6-8, 11070, Belgrade, Serbia
| | - Branka Zukic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Gordana Nikcevic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Milena Ugrin
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Vesna Spasovski
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Sanja Srzentic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Sonja Pavlovic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia
| | - Maja Stojiljkovic
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 11010, Belgrade, Serbia.
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19
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Abstract
More than 950 phenylalanine hydroxylase (PAH) gene variants have been identified in people with phenylketonuria (PKU). These vary in their consequences for the residual level of PAH activity, from having little or no effect to abolishing PAH activity completely. Advances in genotyping technology and the availability of locus-specific and genotype databases have greatly expanded our understanding of the correlations between individual gene variant, residual PAH activity, tetrahydrobiopterin (BH4 ) responsiveness, and the clinical PKU phenotype. Most patients (∼76%) have compound heterozygous PAH gene variants and one mutated allele may markedly influence the activity of the second mutated allele, which in turn may influence either positively or negatively the activity of the biologically active heterotetrameric form of the PAH. While it is possible to predict the level of BH4 responsiveness (∼71%) and PKU severity (∼78%) from the nature of the underlying gene variants, these relationships remain complex and incompletely understood. A greater understanding of these relationships may increase the potential for individualized management of PKU in future. Inherited deficiencies in BH4 metabolism account for about 1%-2% of all hyperphenylalaninemias and are clinically more severe than PKU. Almost 90% of all patients are deficient in 6-pyruvoyl-tetrahydropterin synthase and dihydropteridine reductase.
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Affiliation(s)
- Nenad Blau
- Dietmar-Hopp-Metabolic Center, University Children's Hospital, Heidelberg, Germany
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20
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Aldámiz-Echevarría L, Llarena M, Bueno MA, Dalmau J, Vitoria I, Fernández-Marmiesse A, Andrade F, Blasco J, Alcalde C, Gil D, García MC, González-Lamuño D, Ruiz M, Ruiz MA, Peña-Quintana L, González D, Sánchez-Valverde F, Desviat LR, Pérez B, Couce ML. Molecular epidemiology, genotype-phenotype correlation and BH4 responsiveness in Spanish patients with phenylketonuria. J Hum Genet 2016; 61:731-44. [PMID: 27121329 DOI: 10.1038/jhg.2016.38] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 03/16/2016] [Accepted: 03/24/2016] [Indexed: 01/26/2023]
Abstract
Phenylketonuria (PKU), the most common inborn error of amino acid metabolism, is caused by mutations in the phenylalanine-4-hydroxylase (PAH) gene. This study aimed to assess the genotype-phenotype correlation in the PKU Spanish population and the usefulness in establishing genotype-based predictions of BH4 responsiveness in our population. It involved the molecular characterization of 411 Spanish PKU patients: mild hyperphenylalaninemia non-treated (mild HPA-NT) (34%), mild HPA (8.8%), mild-moderate (20.7%) and classic (36.5%) PKU. BH4 responsiveness was evaluated using a 6R-BH4 loading test. We assessed genotype-phenotype associations and genotype-BH4 responsiveness in our population according to literature and classification of the mutations. The mutational spectrum analysis showed 116 distinct mutations, most missense (70.7%) and located in the catalytic domain (62.9%). The most prevalent mutations were c.1066-11G>A (9.7%), p.Val388Met (6.6%) and p.Arg261Gln (6.3%). Three novel mutations (c.61-13del9, p.Ile283Val and p.Gly148Val) were reported. Although good genotype-phenotype correlation was observed, there was no exact correlation for some genotypes. Among the patients monitored for the 6R-BH4 loading test: 102 were responders (87, carried either one or two BH4-responsive alleles) and 194 non-responders (50, had two non-responsive mutations). More discrepancies were observed in non-responders. Our data reveal a great genetic heterogeneity in our population. Genotype is quite a good predictor of phenotype and BH4 responsiveness, which is relevant for patient management, treatment and follow-up.
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Affiliation(s)
- Luis Aldámiz-Echevarría
- Unit of Metabolism, Cruces University Hospital, BioCruces Health Research Institute, GCV-CIBER de Enfermedades Raras (CIBERER), Plaza de Cruces s/n, Barakaldo, Spain
| | - Marta Llarena
- Unit of Metabolism, Cruces University Hospital, BioCruces Health Research Institute, GCV-CIBER de Enfermedades Raras (CIBERER), Plaza de Cruces s/n, Barakaldo, Spain
| | - María A Bueno
- Metabolic Disorders, Dietetics and Nutrition Unit, Virgen del Rocío University Hospital, Manuel Siurot Avenue s/n, Sevilla, Spain
| | - Jaime Dalmau
- Nutrition and Metabolopathologies Unit, La Fe University Hospital, Bulevar Sur s/n, Valencia, Spain
| | - Isidro Vitoria
- Nutrition and Metabolopathologies Unit, La Fe University Hospital, Bulevar Sur s/n, Valencia, Spain
| | - Ana Fernández-Marmiesse
- Unit of Diagnosis and Treatment of Congenital Metabolic Diseases, Department of Pediatrics, Hospital Clínico Universitario de Santiago de Compostela, CIBERER, Health Research Institute of Santiago de Compostela (IDIS), A Choupana, s/n, Santiago de Compostela, A Coruña, Spain
| | - Fernando Andrade
- Unit of Metabolism, Cruces University Hospital, BioCruces Health Research Institute, GCV-CIBER de Enfermedades Raras (CIBERER), Plaza de Cruces s/n, Barakaldo, Spain
| | - Javier Blasco
- Gastroenterology, Hepatology and Child Nutrition Unit, Carlos Haya University Hospital, Avda. Arroyo de los Ángeles s/n, Málaga, Spain
| | - Carlos Alcalde
- Paediatrics Unit, Río Hortega University Hospital, Valladolid, Spain
| | - David Gil
- Gastroenterology Unit, Virgen de la Arrixaca University Hospital, Ctra. Madrid-Cartagena s/n, El Palmar, Murcia, Spain
| | - María C García
- Metabolic Pathologies Unit, Miguel Servet University Hospital, Zaragoza, Spain
| | | | - Mónica Ruiz
- Paediatrics Unit, Nuestra Señora de la Candelaria University Hospital, Santa Cruz de Tenerife, Spain
| | - María A Ruiz
- Metabolic Pathologies and Neuropaediatrics Unit, Son Espases University Hospital, Palma de Mallorca, Spain
| | - Luis Peña-Quintana
- Paediatric Gastroenterology, Hepatology and Nutrition Unit, Mother and Child Hospital Complex, Avda. Marítima del Sur s/n, Las Palmas de Gran Canaria, Spain
| | - David González
- Metabolic Pathologies Unit, Maternal and Child Hospital, Badajoz, Spain
| | - Felix Sánchez-Valverde
- Gastroenterology and Paediatric Nutrition Unit, Virgen del Camino Hospital, Pamplona, Spain
| | - Lourdes R Desviat
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa CSIC-UAM, CIBERER, IdiPaz, Madrid, Spain
| | - Belen Pérez
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa CSIC-UAM, CIBERER, IdiPaz, Madrid, Spain
| | - María L Couce
- Unit of Diagnosis and Treatment of Congenital Metabolic Diseases, Department of Pediatrics, Hospital Clínico Universitario de Santiago de Compostela, CIBERER, Health Research Institute of Santiago de Compostela (IDIS), A Choupana, s/n, Santiago de Compostela, A Coruña, Spain
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21
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Shen N, Heintz C, Thiel C, Okun JG, Hoffmann GF, Blau N. Co-expression of phenylalanine hydroxylase variants and effects of interallelic complementation on in vitro enzyme activity and genotype-phenotype correlation. Mol Genet Metab 2016; 117:328-35. [PMID: 26803807 DOI: 10.1016/j.ymgme.2016.01.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 01/09/2016] [Indexed: 02/04/2023]
Abstract
BACKGROUND In phenylketonuria (PKU) patients, the combination of two phenylalanine hydroxylase (PAH) alleles is the main determinant of residual enzyme activity in vivo and in vitro. Inconsistencies in genotype-phenotype correlations have been observed in compound heterozygous patients and a particular combination of two PAH alleles may produce a phenotype that is different from the expected one, possibly due to interallelic complementation. METHODS A dual eukaryotic vector system with two distinct PAH proteins N-terminally fused to different epitope tags was used to investigate the co-expression of PAH alleles reported in patients with inconsistent phenotypes. PAH variant proteins were transiently co-transfected in COS-7 cells. PAH activity was measured by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS), and protein expression was measured by Western blot. Genotypes were compared with predicted PAH activity from the PAH locus-specific database (PAHvdb) and with phenotypes and tetrahydrobiopterin (BH4) responsiveness from more than 10,000 PKU patients (BIOPKU database). RESULTS Through the expression and co-expression of 17 variant alleles we demonstrated that interallelic interaction could be both positive and negative. The co-expressions of p.[I65T];[R261Q] (19.5% activity; predicted 43.5%) and p.[I65T];[R408W] (15.0% vs. 26.8% activity) are examples of genotypes with negative interallelic interaction. The co-expressions of p.[E178G];[Q232E] (55.0% vs.36.4%) and p.[P384S];[R408W] (56.1% vs. 40.8%) are examples of positive subunit interactions. Inconsistencies of PAH residual enzyme activity in vitro and of PKU patients' phenotypes were observed as well. The PAH activity of p.[R408W];[A300S] is 18.0% of the wild-type activity; however, 88% of patients with this genotype exhibit mild hyperphenylalaninemias (MHPs). CONCLUSION The co-expression of two distinct PAH variants revealed possible dominance effects (positive or negative) by one of the variants on residual PAH activity as a result of interallelic complementation.
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Affiliation(s)
- Nan Shen
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Caroline Heintz
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, United States
| | - Christian Thiel
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Jürgen G Okun
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Georg F Hoffmann
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Nenad Blau
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany.
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22
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Li N, Jia H, Liu Z, Tao J, Chen S, Li X, Deng Y, Jin X, Song J, Zhang L, Liang Y, Wang W, Zhu J. Molecular characterisation of phenylketonuria in a Chinese mainland population using next-generation sequencing. Sci Rep 2015; 5:15769. [PMID: 26503515 PMCID: PMC4621502 DOI: 10.1038/srep15769] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 10/01/2015] [Indexed: 11/28/2022] Open
Abstract
Phenylketonuria (PKU) is an inherited autosomal recessive disorder of phenylalanine metabolism, mainly caused by a deficiency of phenylalanine hydroxylase (PAH). The incidence of various PAH mutations differs among race and ethnicity. Here we report a spectrum of PAH mutations complied from 796 PKU patients from mainland China. The all 13 exons and adjacent intronic regions of the PAH gene were determined by next-generation sequencing. We identified 194 different mutations, of which 41 are not reported before. Several mutations reoccurred with high frequency including p.R243Q, p.EX6-96A > G, p.V399V, p.R241C, p.R111*, p.Y356*, p.R413P, and IVS4-1G > A. 76.33% of mutations were localized in exons 3, 6, 7, 11, 12. We further compared the frequency of each mutation between populations in northern and southern China, and found significant differences in 19 mutations. Furthermore, we identified 101 mutations that are not reported before in Chinese population, our study thus broadens the mutational spectrum of Chinese PKU patients. Additionally, 41 novel mutations will expand and improve PAH mutation database. Finally, our study offers proof that NGS is effective, reduces screening times and costs, and facilitates the provision of appropriate genetic counseling for PKU patients.
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Affiliation(s)
- Nana Li
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China
| | - Haitao Jia
- BGI-Shenzhen, Building No. 11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong China
| | - Zhen Liu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China
| | - Jing Tao
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China
| | - Song Chen
- BGI-Shenzhen, Building No. 11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong China
| | - Xiaohong Li
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Laboratory of Molecular Epidemiology for birth defect, West China Institute of Women and Children's Health, Sichuan University, Chengdu, China
| | - Ying Deng
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China
| | - Xi Jin
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China
| | - Jiaping Song
- BGI-Shenzhen, Building No. 11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong China
| | - Liangtao Zhang
- BGI-Shenzhen, Building No. 11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong China
| | - Yu Liang
- BGI-Shenzhen, Building No. 11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong China
| | - Wei Wang
- BGI-Shenzhen, Building No. 11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong China
| | - Jun Zhu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, West China Second University Hospital, Sichuan University, Sec. 3 No. 20, South RenMin Road, Chengdu, Sichuan, China.,Laboratory of Molecular Epidemiology for birth defect, West China Institute of Women and Children's Health, Sichuan University, Chengdu, China
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23
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Chen YF, Jia HT, Chen ZH, Song JP, Liang Y, Pei JJ, Wu ZJ, Wang J, Qiu YL, Liu G, Sun DM, Jiang XY. Mutational spectrum of phenylketonuria in Jiangsu province. Eur J Pediatr 2015; 174:1333-8. [PMID: 25894915 DOI: 10.1007/s00431-015-2539-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 04/01/2015] [Accepted: 04/06/2015] [Indexed: 12/22/2022]
Abstract
UNLABELLED Phenylketonuria (PKU) is caused by variants in the phenylalanine hydroxylase (PAH) gene. We systematically investigated all 13 exons of the PAH gene and their flanking introns in 31 unrelated patients and their parents using next-generation sequencing (NGS). A total of 33 different variants were identified in 58 of 62 mutant PAH alleles. The prevalent variants with a relative frequency of 5 % or more were c.721C > T, c.1068C > A, c.611A > G, c.1197A > T, c.728G > A, c.331C > T, and c.442-1G > A. One novel variant was identified in this study-c.699C > G. We studied genotype-phenotype correlations using the Guldberg arbitrary value (AV) system, which revealed a consistency rate of 38 % (8/21) among the 21 predicted phenotypes. The genotype-based prediction of BH4 responsiveness was also evaluated, and 14 patients (45.2 %) were predicted to be BH4 responsive. CONCLUSION This study presents the spectrum of PAH variants in Jiangsu province. The information obtained from the genotype-based prediction of BH4 responsiveness might be used for the rational selection of candidates for BH4 testing. WHAT IS KNOWN • Phenylketonuria (PKU) is caused by variants in the phenylalanine hydroxylase (PAH) gene. • The spectrum of PAH variants in different Chinese populations has been reported. What is new: • This is the first report on the spectrum of PAH variants in Jiangsu province. • This study identified one novel PAH variant-c.699C>G-and and tries to show a genotype-phenotype relationship also regarding BH4-responsiveness.
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Affiliation(s)
- Ya-fen Chen
- Department of Children Health Care, Wuxi Maternal and Child Health Hospital, No.48 Huaishu Alley, Wuxi, Jiangsu Province, China.
| | - Hai-tao Jia
- Beijing Genomics Institute at Shenzhen, Building No.11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong, China.
| | - Zhong-hai Chen
- Beijing Genomics Institute at Shenzhen, Building No.11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong, China.
| | - Jia-ping Song
- Beijing Genomics Institute at Shenzhen, Building No.11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong, China.
| | - Yu Liang
- Beijing Genomics Institute at Shenzhen, Building No.11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong, China.
| | - Jing-jing Pei
- Department of Children Health Care, Wuxi Maternal and Child Health Hospital, No.48 Huaishu Alley, Wuxi, Jiangsu Province, China.
| | - Zhi-jun Wu
- Department of Children Health Care, Wuxi Maternal and Child Health Hospital, No.48 Huaishu Alley, Wuxi, Jiangsu Province, China.
| | - Jing Wang
- Department of Children Health Care, Suqian Maternal and Child Health Hospital, No. 9 Ping-An Road, Suqian, Jiangsu Province, China.
| | - Ya-li Qiu
- Department of Children Health Care, Suqian Maternal and Child Health Hospital, No. 9 Ping-An Road, Suqian, Jiangsu Province, China.
| | - Gang Liu
- Beijing Genomics Institute at Shenzhen, Building No.11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong, China.
| | - Dong-mei Sun
- Beijing Genomics Institute at Shenzhen, Building No.11, Beishan Industrial Zone, Yantian District, Shenzhen, Guangdong, China.
| | - Xin-ye Jiang
- Department of Children Health Care, Wuxi Maternal and Child Health Hospital, No.48 Huaishu Alley, Wuxi, Jiangsu Province, China.
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24
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Vela-Amieva M, Abreu-González M, González-del Angel A, Ibarra-González I, Fernández-Lainez C, Barrientos-Ríos R, Monroy-Santoyo S, Guillén-López S, Alcántara-Ortigoza MA. Phenylalanine hydroxylase deficiency in Mexico: genotype-phenotype correlations, BH4 responsiveness and evidence of a founder effect. Clin Genet 2015; 88:62-7. [PMID: 24941924 DOI: 10.1111/cge.12444] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/13/2014] [Accepted: 06/16/2014] [Indexed: 11/27/2022]
Abstract
The mutational spectrum of the phenylalanine hydroxylase gene (PAH) in Mexico is unknown, although it has been suggested that PKU variants could have a differential geographical distribution. Genotype-phenotype correlations and genotype-based predictions of responsiveness to tetrahydrobiopterin (BH4 ) have never been performed. We sequenced the PAH gene and determined the geographic origin of each allele, mini-haplotype associated, genotype-phenotype correlations and genotype-based prediction of BH4 responsiveness in 48 Mexican patients. The mutational spectrum included 34 variants with c.60+5G>T being the most frequent (20.8%) and linked to haplotype 4.3 possibly because of a founder effect and/or genetic drift. Two new variants were found c.1A>T and c.969+6T>C. The genotype-phenotype correlation was concordant in 70.8%. The genotype-based prediction to BH4 -responsiveness was 41.7%, this information could be useful for the rational selection of candidates for BH4 testing and therapy.
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Affiliation(s)
- M Vela-Amieva
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, México
| | - M Abreu-González
- Programa de Maestría y Doctorado en Ciencias Biológicas, Facultad de Ciencias, Universidad Nacional Autónoma de México, México D.F., México
| | - A González-del Angel
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Instituto Nacional de Pediatría, Secretaría de Salud, México
| | - I Ibarra-González
- Unidad de Genética de la Nutrición, Instituto de Investigaciones Biomédicas, UNAM - Instituto Nacional de Pediatría, Secretaría de Salud, México
| | - C Fernández-Lainez
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, México
| | - R Barrientos-Ríos
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Instituto Nacional de Pediatría, Secretaría de Salud, México
| | - S Monroy-Santoyo
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, México
| | - S Guillén-López
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, México
| | - M A Alcántara-Ortigoza
- Laboratorio de Biología Molecular, Departamento de Genética Humana, Instituto Nacional de Pediatría, Secretaría de Salud, México
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25
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Abstract
Detection of individuals with phenylketonuria (PKU), an autosomal recessively inherited disorder in phenylalanine degradation, is straightforward and efficient due to newborn screening programs. A recent introduction of the pharmacological treatment option emerged rapid development of molecular testing. However, variants responsible for PKU do not all suppress enzyme activity to the same extent. A spectrum of over 850 variants, gives rise to a continuum of hyperphenylalaninemia from very mild, requiring no intervention, to severe classical PKU, requiring urgent intervention. Locus-specific and genotypes database are today an invaluable resource of information for more efficient classification and management of patients. The high-tech molecular methods allow patients' genotype to be obtained in a few days, especially if each laboratory develops a panel for the most frequent variants in the corresponding population.
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Affiliation(s)
- Nenad Blau
- Division of Inborn Metabolic Diseases, University Children's Hospital, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany
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26
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Abstract
OBJECTIVE Identifying phenylalanine hydroxylase (PAH) mutations associated with sapropterin response in phenylketonuria (PKU) would be an advantageous means to determine clinical benefit to sapropterin therapy. METHODS Sapropterin response, defined as a ≥30 % reduction in phenylalanine (Phe) levels after a dose of 10 mg/kg/day sapropterin for week one and 20 mg/kg/day for week two in 112 PKU patients aged 4-45 years, was assessed in an outpatient setting. PAH was sequenced in all patients. Mutations were correlated with sapropterin response. Dietary Phe intake was increased over a 6-week period in responsive patients. RESULTS Forty-six of 112 patients were sapropterin responsive. Genotypes p.[L48S];[L48S] and p.[Y414C];[Y414C] were always associated with response at a low dose. The mutation Y414C (present on 16 alleles) was most frequently associated with response. Patients with presence of the mutation L48S on at least one allele (12 alleles in 7 patients) always showed response to sapropterin. Responsive patients had a mean Phe tolerance increase of 189 % (range 11-742 %). In the 66 nonresponders, mutations R408W (38 alleles) and IVS12+1G>A (18 alleles) were detected most frequently. Genotypes [IVS12+1G>A];[IVS12+1G>A], p.[L348V];[R408W], p.[P281L];[P281L], p.[R158Q];[R408W], and p.[R261Q];[R408W] were always associated with nonresponse. CONCLUSION Data from the study contributes to growing evidence of the relationship between PAH genotype and PKU phenotype. In most cases, response to sapropterin therapy cannot be predicted based on the presence of a single mutation on one allele alone, although the complete PAH genotype may help to predict sapropterin responsiveness in PKU patients.
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