Phenylketonuria (PKU) is a genetic metabolic disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene, with an incidence rate in China of approximately 1 in 11,000. PKU exhibits high heterogeneity, making the study of genotype–phenotype correlations essential for effective diagnosis and treatment.
Methods:
This study aimed to analyze the genotype–phenotype correlation in pediatric PKU patients in China, with a special focus on hotspot mutations across different regions.
We compared the accuracy of two prediction models: the allele phenotype value/genotype–phenotype value system and the prediction system based on the sum of assigning value (AV) scores from PAH activity, evaluating both models based on available patient data from various regions.
Results:
The majority of genotypes in PKU patients were found to be compound heterozygotes. Classical PKU patients (cPKU) accounted for the highest proportion (44%), while the percentage of patients with mild hyperphenylalaninemia was relatively low at 22%. Among the eight regions studied, the APV/GPV system demonstrated higher accuracy (72.02%) compared with the AV score prediction system (56.82%, p < 0.05); however, for the cPKU phenotype alone, the difference in accuracy was not significant (p > 0.05).
Discussion:
This study provides insights into the relationship between genotypes and phenotypes in PKU patients across different regions of China, emphasizing the importance of analyzing hotspot mutations for understanding genotype–phenotype correlations. The findings highlight the need to enhance hotspot mutation spectra for PKU patients and advocate for the development of more accurate prediction models, which can offer better protection for PKU patients and alleviate the burden on patients and their families.
Aldámiz-EchevarríaL, LlarenaM, BuenoMA, et al.Molecular epidemiology, genotype-phenotype correlation and BH4 responsiveness in Spanish patients with phenylketonuria. J Hum Genet, 2016; 61(8):731–744; doi: 10.1038/jhg.2016.38
2.
CannetC, BayatA, Frauendienst-EggerG, et al.Phenylketonuria (PKU) urinary metabolomic phenotype is defined by genotype and metabolite imbalance: Results in 51 early treated patients using ex vivo H-NMR analysis. Molecules, 2023; 28(13):4916; doi: 10.3390/molecules28134916
3.
ChenT, XuW, WuD, et al.Mutational and phenotypic spectrum of phenylalanine hydroxylase deficiency in Zhejiang Province, China. Sci Rep, 2018; 8(1):17137.
4.
DanieleA, ScalaI, CardilloG, et al.Functional and structural characterization of novel mutations and genotype-phenotype correlation in 51 phenylalanine hydroxylase deficient families from Southern Italy. FEBS J, 2009; 276(7):2048–2059; doi: 10.1111/j.1742-4658.2009.06940.x
5.
DatekiS, WatanabeS, NakatomiA, et al.Genetic background of hyperphenylalaninemia in Nagasaki, Japan. Pediatr Int, 2016; 58(5):431–433; doi: 10.1111/ped.12924
6.
DjordjevicM, KlaassenK, SarajlijaA, et al.Molecular genetics and genotype-based estimation of BH4-responsiveness in Serbian PKU patients: Spotlight on phenotypic implications of p.p.Leu48Ser. JIMD Rep, 2013; 9:49–58; doi: 10.1007/8904_2012_178
7.
DobrowolskiSF, PeyAL, KochR, et al.Biochemical characterization of mutant phenylalanine hydroxylase enzymes and correlation with clinical presentation in hyperphenylalaninaemic patients. J Inherit Metab Dis, 2009; 32(1):10–21; doi: 10.1007/s10545-008-0942-6
8.
ElhawaryNA, AlJahdaliIA, AbumansourIS, et al.Genetic etiology and clinical challenges of phenylketonuria. Hum Genomics, 2022; 16(1):22; doi: 10.1186/s40246-022-00398-9
9.
FangY, GaoJ, GuoY, et al.Allelic phenotype prediction of phenylketonuria based on the machine learning method. Hum Genomics, 2023; 17(1):34; doi: 10.1186/s40246-023-00481-9
10.
FerreiraF, AzevedoL, NeivaR, et al.Phenylketonuria in Portugal: Genotype-phenotype correlations using molecular, biochemical, and haplotypic analyses. Mol Genet Genomic Med, 2021; 9(3):e1559; doi: 10.1002/mgg3.1559
11.
FishchukL, RossokhaZ, OlkhovichN, et al.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.
12.
GaoJ, LiX, GuoY, et al.Identification of phenylketonuria patient genotypes using single-gene full-length sequencing. Hum Genomics, 2022; 16(1):23; doi: 10.1186/s40246-022-00397-w
13.
GarbadeSF, ShenN, HimmelreichN, et al.Allelic phenotype values: A model for genotype-based phenotype prediction in phenylketonuria. Genet Med, 2019; 21(3):580–590; doi: 10.1038/s41436-018-0081-x
14.
GerstingSW, KemterKF, StaudiglM, et al.Loss of function in phenylketonuria is caused by impaired molecular motions and conformational instability. Am J Hum Genet, 2008; 83(1):5–17; doi: 10.1016/j.ajhg.2008.05.013
15.
GuldbergP, ReyF, ZschockeJ, et al.A European multicenter study of phenylalanine hydroxylase deficiency: Classification of 105 mutations and a general system for genotype-based prediction of metabolic phenotype. Am J Hum Genet, 1998; 63(1):71–79; doi: 10.1086/301920
16.
HimmelreichN, ShenN, OkunJG, et al.Relationship between genotype, phenylalanine hydroxylase expression and in vitro activity and metabolic phenotype in phenylketonuria. Mol Genet Metab, 2018; 125(1–2):86–95; doi: 10.1016/j.ymgme.2018.06.011
17.
HuHL, LiWD, ShaoZY, et al.Variation of phenylalanine hydroxylase gene in 72 children with hyperphenylalaninemia in Anhui province. Shandong Medical Journal, 2018; 3:70–72; doi: 10.3969/j.issn.1002-266X.2018.03.022
18.
Jeannesson-ThivisolE, FeilletF, ChéryC, et al.Genotype-phenotype associations in French patients with phenylketonuria and importance of genotype for full assessment of tetrahydrobiopterin responsiveness. Orphanet J Rare Dis, 2015; 10:158; doi: 10.1186/s13023-015-0375-x
19.
KhaghaniF, EshraghiP, HamzehloeiT. Tetrahydrobiopterin responsiveness in Phenylalanine hydroxylase deficient patients from North-east of Iran: Genotype-phenotype correlation, identification of a novel mutation and 7 new responsive genotypes. Eur J Med Genet, 2022; 65(9):104536; doi: 10.1016/j.ejmg.2022.104536
20.
LeeDH, KooSK, LeeKS, et al.The molecular basis of phenylketonuria in Koreans. J Hum Genet, 2004; 49(11):617–621; doi: 10.1007/s10038-004-0197-5
21.
LiN, JiaH, LiuZ, et al.Molecular characterisation of phenylketonuria in a Chinese mainland population using next-generation sequencing. Sci Rep, 2015; 5:15769; doi: 10.1038/srep15769
22.
LiangY, HuangMZ, ChengCY, et al.The mutation spectrum of the phenylalanine hydroxylase (PAH) gene and associated haplotypes reveal ethnic heterogeneity in the Taiwanese population. J Hum Genet, 2014; 59(3):145–152; doi: 10.1038/jhg.2013.136
23.
LiuY, YeungWSB, ChiuPCN, CaoD. Computational approaches for predicting variant impact: An overview from resources, principles to applications. Front Genet, 2022; 13:981005.
24.
MaCX, FangLL, LiLX, et al.Study on gene mutation ofphenylalanine hydroxylase deficiency in Shijiazhuang. International Journal of Laboratory Medicine, 2022; 171:161–166; doi: 10.3969/j.issn.1673-4130.2022.02.007
25.
MuradH, DabboulA, MoassasF, et al.Mutation spectrum of phenylketonuria in Syrian population: Genotype-phenotype correlation. Gene, 2013; 528(2):241–247; doi: 10.1016/j.gene.2013.07.001
26.
Namdar AligoodarziPN, RostamiG, KazemiNSR, HamidM. Multiplex Snapshot minisequencing for the detection of common PAH gene mutations in Iranian patients with Phenylketonuria. Iran Biomed J, 2023; 27(1):46–57; doi: 10.52547/ibj.3856
27.
NgiwsaraL, VatanavicharnN, SawangareetrakulP, et al.Molecular characterization of Thai patients with phenylalanine hydroxylase deficiency and in vitro functional study of two novel PAH variants. Mol Biol Rep, 2021; 48(3):2063–2070; doi: 10.1007/s11033-021-06163-w
28.
PolakE, FicekA, RadvanszkyJ, et al.Phenylalanine hydroxylase deficiency in the Slovak population: Genotype-phenotype correlations and genotype-based predictions of BH4-responsiveness. Gene, 2013; 526(2):347–355; doi: 10.1016/j.gene.2013.05.057
29.
RovelliV, CefaloG, ErcoliV, et al.Hyperphenylalaninemias genotyping: Results of over 60 years of history in Lombardy, Italy. Endocrinol Diabetes Metab, 2023; 6(2):e396; doi: 10.1002/edm2.396
30.
ShiXT, CaiJ, WangYY, et al.Newborn screening for inborn errors of metabolism in mainland china: 30 years of experience. JIMD Rep, 2012; 6:79–83; doi: 10.1007/8904_2011_119
31.
TaoY, HanD, ShenH, LiX. Spectrum of PAH gene mutations and genotype-phenotype correlation in patients with phenylalanine hydroxylase deficiency from Shanxi province. Brain Dev, 2021; 43(2):220–229; doi: 10.1016/j.braindev.2020.08.012
32.
TheronM, JeannessonE, CantonM, et al.Blood phenylalanine fluctuation in phenylketonuric children treated by BH4 or low-phenylalanine diet from birth. Sci Rep, 2023; 13(1):9559; doi: 10.1038/s41598-023-36550-1
33.
TresbachRH, Sperb-LudwigF, Ligabue-BraunR, et al.Phenylketonuria diagnosis by massive parallel sequencing and genotype-phenotype association in Brazilian patients. Genes (Basel), 2020; 12(1):20; doi: 10.3390/genes12010020
34.
van SpronsenFJ, BlauN, HardingC, et al.Phenylketonuria. Nat Rev Dis Primers, 2021; 7(1):36; doi: 10.1038/s41572-021-00267-0
35.
van WegbergAMJ, MacDonaldA, AhringK, et al.The complete European guidelines on phenylketonuria: Diagnosis and treatment. Orphanet J Rare Dis, 2017; 12(1):162; doi: 10.1186/s13023-017-0685-2
36.
Vela-AmievaM, Abreu-GonzálezM, González-del AngelA, et al.Phenylalanine hydroxylase deficiency in Mexico: Genotype-phenotype correlations, BH4 responsiveness and evidence of a founder effect. Clin Genet, 2015; 88(1):62–67; doi: 10.1111/cge.12444
37.
Vieira NetoE, LaranjeiraF, QuelhasD, et al.Mutation analysis of the PAH gene in phenylketonuria patients from Rio de Janeiro, Southeast Brazil. Mol Genet Genomic Med, 2018; 6(4):575–591; doi: 10.1002/mgg3.408
38.
WangDJ, ZhangJ, LiuH, et al.Gene mutations in children with phenylalanine hydroxylase deficiency: An analysis of 45 cases in some regions of Chongqing. Journal of Third Military Medical University, 2021; 43(9):876–882; doi: 10.16016/j.1000-5404.202010198
39.
WangX, WangY, MaD, et al.Neonatal screening and genotype-phenotype correlation of hyperphenylalaninemia in the Chinese population. Orphanet J Rare Dis, 2021; 16(1):214; doi: 10.1186/s13023-021-01846-w
40.
WettsteinS, UnderhaugJ, PerezB, et al.Linking genotypes database with locus-specific database and genotype-phenotype correlation in phenylketonuria. Eur J Hum Genet, 2015; 23(3):302–309.
41.
WyseATS, Dos SantosTM, SeminottiB, LeipnitzG. Insights from animal models on the pathophysiology of hyperphenylalaninemia: Role of mitochondrial dysfunction, oxidative stress and inflammation. Mol Neurobiol, 2021; 58(6):2897–2909; doi: 10.1007/s12035-021-02304-1
42.
XiangL, TaoJ, DengK, et al.Phenylketonuria incidence in China between 2013 and 2017 based on data from the Chinese newborn screening information system: A descriptive study [published correction appears in BMJ Open. 2020 Jan 10;10(1):e031474corr1. doi: 10.1136/bmjopen-2019-031474corr1.]. BMJ Open, 2019; 9(8):e031474; doi: 10.1136/bmjopen-2019-031474
43.
YanY, ZhangC, JinX, et al.Mutation spectrum of PAH gene in phenylketonuria patients in Northwest China: Identification of twenty novel variants. Metab Brain Dis, 2019; 34(3):733–745; doi: 10.1007/s11011-019-0387-7
44.
ZhangZ, GaoJJ, FengY, et al.Mutational spectrum of the phenylalanine hydroxylase gene in patients with phenylketonuria in the central region of China. Scand J Clin Lab Invest, 2018; 78(3):211–218; doi: 10.1080/00365513.2018.1434898
45.
ZhangZ, ZhangLQ, DuW, et al.Relationship between genotype and phenotype of phenylalanine hydroxylase deficiency in children and its clinical application. Journal of Clinical Pediatrics, 2020; 38(9):671; doi: 10.3969/j.issn.1000-3606.2020.09.008
ZhouJ, ZengY, QiuX, et al.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(11):10409–10419; doi: 10.1007/s11033-022-07579-8
48.
ZhuT, YeJ, HanL, et al.Variations in genotype-phenotype correlations in phenylalanine hydroxylase deficiency in Chinese Han population. Gene, 2013; 529(1):80–87; doi: 10.1016/j.gene.2013.07.079
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
