OBJECTIVES: To investigate the molecular epidemiology of children with phenylketonuria (PKU) in Gansu, China, providing foundational data for intervention strategies. METHODS: A retrospective analysis was conducted on 1 159 PKU families who attended Gansu Provincial Maternity and Child Care Hospital from January 2012 to December 2024. Sanger sequencing, multiplex ligation-dependent probe amplification, whole exome sequencing, and deep intronic variant analysis were used to analyze the PAH gene. RESULTS: For the 1 159 children with PKU, 2 295 variants were identified in 2 318 alleles, resulting in a detection rate of 99.01%. The detection rates were 100% (914/914) in 457 classic PKU families, 99.45% (907/912) in 456 mild PKU families, and 96.34% (474/492) in 246 mild hyperphenylalaninemia families. The 2 295 variants detected comprised 208 distinct mutation types, among which c.728G>A (14.95%, 343/2 295) had the highest frequency, followed by c.611A>G (4.88%, 112/2 295) and c.721C>T (4.79%, 110/2 295). The cumulative frequency of the top 23 hotspot variants reached 70.28% (1 613/2 295), and most variant alleles were detected in exon 7 (29.19%, 670/2 295). CONCLUSIONS Deep intronic variant analysis of the PAH gene can improve the genetic diagnostic rate of PKU. The development of targeted detection kits for PAH hotspot variants may enable precision screening programs and enhance preventive strategies for PKU.
Humans ; Phenylketonurias/epidemiology* ; Female ; Male ; Retrospective Studies ; Phenylalanine Hydroxylase/genetics* ; Mutation ; Child, Preschool ; China/epidemiology* ; Child ; Infant

OBJECTIVE: To explore the spectrum of genetic variants and phenotypes of Phenylalanine hydroxylase deficiency (PAHD) in Lianyungang area and the correlation between genotype and phenotypes among the patients. METHODS: Eighty children with Hyperphenylalaninemia (HPA) diagnosed at the Lianyungang Branch of Jiangsu Provincial Newborn Screening Center between January 2015 and December 2022 were enrolled. Peripheral blood samples were collected for genetic analysis using next generation sequencing (NGS), Sanger sequencing, and multiplex ligation-dependent probe amplification (MLPA) to identify the variants of PAH gene. Clinical and phenotypic data were concurrently analyzed to investigate the correlation between the types of PAH gene variant and phenotypes. This study was approved by the Medical Ethics Committee of Lianyungang Maternal and Child Health Care Hospital (Ethics No.: XM2022041). RESULTS: PAH gene variants were identified in 93.75% (75/80) of the children, classified as PAHD cases, while 6.25% (5/80) harbored PTS gene variants. Of the 150 PAH alleles from 75 PAHD children, a total of 152 variants (55 distinct types) were detected, with a detection rate of 100%. 80.26% (122/152) of the variants were located in exons, with the main types being missense variants (67.11%, 102/152). 53.29% (81/152) of coding sequence variants have occurred in the PAH gene's catalytic center region, while 19.74% (30/152) of the variants involved non-coding sequences. The phenotypes of the 75 PAHD children were evenly distributed. The re-screened Phe concentrations and Phe/Tyr ratios of classic-phenylketonuria (CPKU) and mild-phenylketonuria (MPKU) patients were markedly higher than initial screening values (P < 0.001, P < 0.001; P = 0.004, P = 0.016). The genotypes of the PAHD patients mostly occurred as compound heterozygotes, and different mutation positions and variant types have significantly affected the phenotypes (P = 0.042, P = 0.045). APV/GPV genotype-phenotype analysis of 61 patients showed high consistency between predicted and actual phenotypes (κ = 0.755, P < 0.001). CONCLUSION PAH gene variants were detected in most HPA children from Lianyungang area. The location and type of PAH gene variants has correlated with the severity of the phenotype, and the non-coding sequence variants and non-missense variants may aggravate the phenotype, and the APV/GPV model has predicted the phenotype with high consistency with the actual phenotype.
Humans ; Phenylalanine Hydroxylase/genetics* ; Female ; Phenylketonurias/enzymology* ; Male ; Phenotype ; Genotype ; Child ; Infant ; Infant, Newborn ; Child, Preschool ; China ; Mutation ; Alleles

OBJECTIVES: To analyze the results of neonatal screening for congenital hypothyroidism (CH) and hyperphenylalaninemia (HPA) in Zhejiang province from 1999 to 2022. METHODS: A total of 11 922 318 newborns were screened from September 1999 and December 2022 in Zhejiang province. The blood thyroid stimulating hormone (TSH) levels were measured by a fluorescence method and blood phenylalanine (Phe) levels were measured by fluorescence method or tandem mass spectrometry. TSH≥9 μIU/mL was considered positive for CH, while Phe>120 μmol/L and/or Phe/Tyr ratio>2.0 were considered positive for HPA. The positive newborns in screening were recalled, and the gene variations were detected by high-throughput sequencing and MassARRAY tests. RESULTS: The overall neonatal screening rate during 1999-2022 was 89.41% (11 922 318/13 333 929) and the screening rate was increased from 6.46% in 1999 to 100.0% in 2022. A total of 8924 cases of CH were diagnosed among screened newborns with an incidence rate of 1/1336. A total of 563 cases of HPA were diagnosed, including 508 cases of classic phenylketonuria (cPKU) and 55 cases of tetrahydrobiopterin deficiency (BH4D), with an incidence rate of 1/21 176. Ninety-seven out of 8924 cases of CH underwent genetic analysis. Gene mutations were detected in 9 CH related genes, the highest frequency mutations were found in DUOX2 gene (69.0%) with c.3329G>A (p.R1110Q) (18.2%) and c.1588A>T (p.K530X) (17.3%) as the hotspot mutations. There were 81 PAH gene variants detected in a total of 250 cases of cPKU, and c728G>A (p.R243Q) (24.4%), c.721C>T (p.R241C) (15.0%) were the hotspot mutations. Meanwhile 7 novel variants in PAH gene were detected: c.107C>A (p.S36*), c.137G>T (p.G46V), c.148A>G(p.K50E), c.285C>T (p.I95I), c.843-10delTTCC, exon4-7del and c.1066-2A>G. There were 12 PTS gene variants detected in 36 cases of BH4D, and c.259C>T (p.P87S) (31.9%) was the hotspot mutation. CONCLUSIONS The incident of CH has increased from 1999 to 2022 in Zhejiang province, and it is higher than that of national and global levels; while the incidence of HPA is similar to the national average. DUOX2 gene variation is the most common in CH patients; c.728G>A (p.R243Q) is the hotspot mutation in cPKU patients, while c.259C>T (p.P87S) is the hotspot mutation in BH4D patients.
Humans ; Infant, Newborn ; Neonatal Screening ; Dual Oxidases ; Congenital Hypothyroidism/genetics* ; Phenylketonurias/genetics* ; Thyrotropin

OBJECTIVES: To retrospectively analyze the variation and characteristics of phenylalanine hydroxylase (PAH) gene, and to observe the long-term treatment effect and follow-up of newborns with PAH deficiency. METHODS: Clinical data, treatment and follow-up results of 198 patients with PAH deficiency diagnosed by newborn screening in Jinan from 1996 to 2021 were collected. The genetic analysis of 55 patients with PAH deficiency diagnosed by newborn screening in Jinan and 213 patients referred from the surrounding areas of Jinan were summarized. Gene variations were checked by a customized Panel gene detection method. Blood phenylalanine-concentration and physical development indicators including height and weight were regularly monitored. Intellectual development was assessed using a neuropsychological development scale for patients aged 0-6 years and academic performance, and brain injury in patients was assessed using brain magnetic resonance imaging. RESULTS: c.728G>A, c.158G>A, c.721C>T, c.1068C>A, c.611A>G variations were common in PAH gene. The genotype of c.158G>A variation is compound heterozygous variation, with mainly a mild hyperpheny-lalaninemia. 168 patients with PAH deficiency who were followed-up regularly had normal physical development without dwarfism or malnutrition. Among the 33 preschool patients who underwent mental development assessment, 2 were mentally retarded and the initial treatment age was older than 6 months. Nine patients with an average age of (17.13±2.42) years completed brain magnetic resonance imaging, one case was normal, and 8 cases were abnormal. There were patchy or patchy hyperintense foci near the bilateral lateral ventricles on T₂WI, and the intellectual development was normal. Compared with the other eight patients, the blood phenylalanine concentration of the normal child was better and stably controlled within the ideal range. CONCLUSIONS c.728G>A, c.158G>A, c.721C>T, c.1068C>A, c.611A>G variations were common in PAH gene. After standardized treatment, most patients with PAH deficiency diagnosed by screening can obtain normal growth and intellectual development in adolescence, but there are different degrees of organic lesions in the cerebral white matter.
Child ; Child, Preschool ; Adolescent ; Humans ; Infant, Newborn ; Young Adult ; Adult ; Neonatal Screening ; Follow-Up Studies ; Retrospective Studies ; Phenylketonurias/genetics* ; Phenylalanine Hydroxylase/genetics* ; Phenylalanine/therapeutic use* ; Mutation

Consensus ; Humans ; Nutritional Requirements ; Phenylalanine ; blood ; Phenylalanine Hydroxylase ; deficiency ; Phenylketonurias ; diagnosis ; diet therapy ; genetics ; Practice Guidelines as Topic

OBJECTIVE: To explore the characteristics of PAH gene variants among 113 phenylketonuria patients from Henan Province. METHODS: The 13 exons of the PAH gene were subjected to PCR amplification and direct sequencing. Large fragment deletion and duplication of the PAH gene were detected with a multiple ligation-dependent probe amplification (MLPA) assay. RESULTS: In total 195 point variants and 3 large fragment deletions were detected among the 226 alleles, with the detection rates being 86.28% and 1.33%, respectively. Variants of p.Arg243Gln (18.14%), p.Arg111X (6.19%), p.Arg53His (5.31%), EX6-96A>G (5.31%), p.Tyr356X (4.87%) and p.Val399Val (4.42%) were relatively common. Most of the variants were located in exons 7, 11, 3 and 6. Missense variations were most common. Four novel variations were detected, which included c.1016C>A (p.Ser339Tyr), c.1000T>C (p.Cys334Arg), c.1110G>T (p.Glu370Asp), and IVS6+1G>T. CONCLUSION The PAH gene variations in Henan Province have featured extensive allelic heterogeneity and variety.
China ; Exons ; Humans ; Mutation, Missense ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics ; Point Mutation ; Sequence Deletion

OBJECTIVETo explore the characteristics of (PAH) gene mutations among patients with phenylketonuria (PKU) from Linyi area of Shandong Province.

METHODSFor 51 children affected with PKU and their parents, the 13 exons and their flanking intronic sequences of the PAH gene were directly sequenced with Sanger method.

RESULTSPAH gene mutations were detected in all of the 102 alleles of the patients, which included 31 types of mutations. Common mutations included R243Q (17/102, 16.67%), IVS4-1G to A (9/102, 8.82%), R241C (8/102, 7.84%), R111X (8/102, 7.84%), and V399V (8/102, 7.84%). In addition, two novel mutations, D101N, 345-347del, have been detected. The 31 types of mutations included missense, nonsense, deletion, and splicing mutations, which were mainly located in exons 7 (29, 28.43%), 11 (18, 17.65%), 3 (16, 15.69%) and 12 (13, 12.75%).

CONCLUSIONMutations of the PAH gene in Linyi region mainly distributed in exons 7, 11, and 3, and the most common mutation were R243Q. Two novel mutations, D101N and 345-347del, have been detected.

Base Sequence ; Child ; Child, Preschool ; China ; Exons ; Female ; Humans ; Infant ; Male ; Molecular Sequence Data ; Mutation ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; enzymology ; genetics

OBJECTIVETo delineate the mutation spectrum of phenylalanine hydroxylase (PAH) gene among patients affected with phenylalanine hydroxylase deficiency (PAHD) in Henan Province of China, and to explore the correlation between the genotype and the phenotype.

METHODSA total of 155 affected children were recruited. Potential mutation of the PAH gene were analyzed by direct sequencing. The genotype-phenotype correlation was analyzed by matching the expected and observed phenotypes.

RESULTSOver 72 mutations and 108 genotypes have been identified. There were 7 homozygous mutations, including 1 case with EX6-96A>G/EX6-96A>G, 1 with R241C/R241C, 1 with R413P/R413P, and 4 with R243Q/R243Q. Among these, 6 patients have presented classic PKU phenotypes, except for a R241C/R241C genotype which has led to mild PKU. In 104 patients carrying compound PAH mutations, 52 were classic, 34 were mild and 39 had mild HPA. Patients who were heterozygous for EX6-96A>G/R241C, R243Q/A434D, EX6-96A>G/R413P and EX6-96A>G/ R241C were found with both the classic PKU and mild PKU phenotypes. Common mutations associated with mild HPA have included R53H, R243Q, V399V and H107R. The common mutations associated with mild PKU included R243Q, R241C, EX6-96A>G, and IVS4-1G>A. The prevalent mutations in classic PKU were R243Q, EX6-96A>G and V399V. The consistency between prediction of the biochemical genotype and observed phenotype was 77.78%, especially in classic PKU, the consistency was up to 82.14%. Significant correlations were disclosed between pretreatment levels of phenylalanine and AV sum (r=-0.6729, P < 0.01).

CONCLUSIONThe mutation spectrum of PAH gene in Henan seems to differ from that of other regions. Independent assortment of mutant alleles may result in a complex genotype-phenotype correlation, but the genotypes of PAHD patients have correlated with the phenotype.

Female ; Genotype ; Humans ; Male ; Mutation ; Phenotype ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics

OBJECTIVETo study the characteristics of phenylalanine hydroxylase gene (PAH) mutations in patients with PAH deficiency in Fujian population.

METHODSPeripheral blood samples of 36 patients and their parents with classical type phenylketouria (PKU) were collected. Genomic DNA was extracted. Following PCR amplification, DNA sequencing was carried out to identify the origins of mutations.

RESULTSTwenty types mutations were identified in 63 of the 72 alleles. The most common mutations were R241C, R408Q and Ex6-96A>G, which respectively accounted for 15.9%, 12.7% and 11.1% of all mutant alleles. The c.189_190dupTGAC mutation was first reported. R241C was associated with 28% of mild hyperphenylalaninemia and R408Q is associated with 25% of classical PKU.

CONCLUSIONThere is a specific spectrum of PAH gene mutation in Fujian region. R241C, R408Q and Ex6-96A>G are the most common mutations.

Adolescent ; Alleles ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Child ; Child, Preschool ; China ; Female ; Genotype ; Humans ; Male ; Molecular Sequence Data ; Mutation ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; enzymology ; genetics

OBJECTIVETo investigate the mutations of phenylalanine hydroxylase (PAH) gene in 20 phenylketonuria (PKU) patients from Yunnan.

METHODSThe 13 exons and the splicing regions of 12 introns of the PAH gene were sequenced to detect mutations in 20 unrelated PKU patients.

RESULTSPAH gene sequencing has revealed 15 types of mutations, in which the most frequently mutation was p.R243Q (30.0%), followed by p.Y356X(10.0%), p.R111X (7.5%), IVS4+2T>A (7.5%) and p.V399V (7.5%). Exons 7, 11, 3 and introns 4, 11 were most frequently involved. Six novel mutations, including c.59A>C, c.60G>C, c.690_691insG, c.1119_1120insT, c.441+2T>A, c.842+4A>T and c.1200+1T>G were detected.

CONCLUSIONPAH gene mutations identified in Yunnan are more similar to those of northern China, with R243R being the most common, though there are still certain characteristics for the type and frequency of mutations.

Adolescent ; Adult ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Child ; China ; Female ; Humans ; Male ; Molecular Sequence Data ; Mutation ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; enzymology ; genetics ; Young Adult