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

Two trials of external quality assessment for conventional newborn screening tests for phenylketonuria, congenital hypothyroidism, galactosemia, maple syrup urine disease and homocytinuria and for the newborn screening tests using tandem mass spectrometry (MS/MS) were performed in 2009. Total 20 specimens were distributed to 13 laboratories. All the control materials were send as dried blood spots. The response rate was 100%. The mean, SD, CV, median and range were analyzed. In addition, two trials of external quality assessment for glycohemoglobin (HbA1c) were performed in 2009. Total 6 samples were distributed to 196 laboratories and the response rate was 97.2% (175/180) and 98.5% (193/196) in each trial. From this trial, we performed accuracy-based survey which used challenge specimens that were free from matrix effects and had target values traceable to certified reference material. Bias between each participants result and reference target value were evaluated.
Bias (Epidemiology) ; Congenital Hypothyroidism ; Galactosemias ; Humans ; Infant, Newborn ; Korea ; Maple Syrup Urine Disease ; Mass Screening ; Phenylketonurias ; Tandem Mass Spectrometry

A consistent finding of many studies describing the spectrum of mutant phenylalanine hydroxylase (PAH) alleles underlying hyperphenylalaninemia is the impossibility of achieving a 100% mutation ascertainment rate using conventional gene-scanning methods. These methods include denaturing gradient gel electrophoresis (DGGE), denaturing high performance liquid chromatography (DHPLC), and direct sequencing. In recent years, it has been shown that a significant proportion of undetermined alleles consist of large deletions overlapping one or more exons. These deletions have been difficult to detect in compound heterozygotes using gene-scanning methods due to a masking effect of the non-deleted allele. To date, no systematic search has been carried out for such exon deletions in Italian patients with phenylketonuria or mild hyperphenylalaninemia. We used multiplex ligation- dependent probe amplification (MLPA), comparative multiplex dosage analysis (CMDA), and real-time PCR to search for both large deletions and duplications of the phenylalanine hydroxylase gene in Italian hyperphenylalaninemia patients. Four deletions removing different phenylalanine hydroxylase (PAH) gene exons were identified in 12 patients. Two of these deletions involving exons 4-5-6-7-8 (systematic name c.353-?_912 + ?del) and exon 6 (systematic name c.510-?_706 + ?del) have not been reported previously. In this study, we show that exon deletion of the PAH gene accounts for 1.7% of all mutant PAH alleles in Italian hyperphenylalaninemics.
DNA Mutational Analysis/*methods ; Disease Progression ; Exons/genetics ; Gene Frequency ; Humans ; Italy ; Phenylalanine Hydroxylase/*genetics/metabolism ; Phenylketonurias/epidemiology/*genetics/physiopathology ; Reverse Transcriptase Polymerase Chain Reaction ; Sequence Deletion/genetics

OBJECTIVEThe retrospective study was carried out to investigate the nation-wide neonatal screening program in the past 22 years in China. This study aimed to summarize the experience, analyze the questions and concerns in the screening program.

METHODSAll data on the national neonatal screening in the past 22 years were from National Center for Clinical Laboratory. Study items included the development and mode of the program, screening method adopted as well as the clinical records of prevalence, treatment and follow-up etc.

RESULTSNeonatal screening has become universal since 1985 in China. There were three modes of screening and treatment. From 1985 to 2006, a total of 13,229,242 newborns were screened for congenital hypothyroidism (CH) and 6505 were diagnosed as CH at a prevalence of 49.2/100,000; a total of 13,666,750 newborns were screened for phenylketonuria (PKU), and 1,170 were diagnosed as PKU at a prevalence of 8.6/100,000. The prevalence of CH increased year by year and the western regions in China had a much higher prevalence. The prevalence of PKU was relatively more steady than that of CH in China.

CONCLUSIONSNeonatal screening is of paramount importance in preventing mental retardation and developmental delay after CH and PKU. It is necessary to attach more importance to increase the rate of coverage, screening and treatment, as well as social awareness of neonatal screening. It is important to focus on establishment of new screening techniques so as to improve the level of child health care in China.

China ; epidemiology ; Congenital Hypothyroidism ; epidemiology ; Humans ; Infant, Newborn ; Neonatal Screening ; Phenylketonurias ; epidemiology ; Prevalence ; Retrospective Studies

OBJECTIVETo investigate the development of differential diagnosis of tetrahydrobiopterin (BH4) deficiency among patients with hyperphenylalaninemia (HPA) in provinces or cities of China and to investigate the incidence of BH4 deficiency.

METHODSOf the thirteen hundreds and ninety-two patients with HPA received, the differential diagnosis for BH4 deficiency during 1993 - 2007 were enrolled in this study. Of which, 591 patients came from outpatient and 801 patients' samples from other provinces or cities were sent to author's laboratory to investigate the case number of differential diagnosis for BH4 deficiency in provinces or cities of China according to the data from both outpatient case histories and laboratory as to investigating the development of differential diagnosis in the whole country. To discuss the diagnostic criteria for BH4 deficiency was according to the results of urinary pterin analysis, determination of dihydropteridine reductase (DHPR) activity and the tetrahydrobiopterin loading test as well as to get the incidence of BH4 deficiency and find some provinces or cities with higher incidence of BH4 deficiency in China.

RESULTS(1) The number of HPA patients, who were performed by urinary pterin analysis and the determination of DHPR activity, were remarkably increased in last three years (2005 - 2007). The patient numbers of both urinary pterin analysis and DHPR activity determination were 217 and 198 respectively in 2005. And in 2007 they increased to 511 and 458, which was about 2.3 times than that in 2005. The patients came from 29 provinces or cities in 2007. (2) The urinary biopterin and biopterin percent were key marks for diagnosis of 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency. The less than 5% [(1.41 +/- 1.10)%] biopterin percent and very low biopterin level [(0.14 +/- 0.17) mmol/mol Cr] were found in 96.83% (61/63) patients with PTPS deficiency in this study. The blood phenylalanine level was remarkably decreased to normal range at 2 - 6 hours after BH4 loading test. The very low DHPR activity was a final diagnostic mark for DHPR deficiency. The very low DHPR activities of 0.27 nmol/(min x 5 mm disc) (6.11% - 7.00% of normal controls) were found in two patients with DHPR deficiency in this study. (3) The incidences of PTPS deficiency and DHPR deficiency among 1392 patients with hyperphenylalaninemia were 8.41% (117/1392) and 0.18% (2/1108) respectively. About 67.23% (80/119) patients with BH4 deficiency came from the south of Yangtze liver. The 80% (8/10) provinces or cities with higher incidence of BH4 deficiency are located in eastern and southern China. The incidence of PTPS deficiency among patients with HPA and normal newborns was 10.81% (8/74) and 0.007 per thousand (8/1,121,429) respectively in Shanghai, China according to data from neonatal screening.

CONCLUSIONThe awareness of differential diagnosis for BH4 deficiency from clinic pediatricians has been increased in most provinces or cities of China in last three years, but it should be more strengthened.

Biopterin ; analogs & derivatives ; deficiency ; China ; epidemiology ; Diagnosis, Differential ; Humans ; Incidence ; Infant, Newborn ; Neonatal Screening ; Phenylketonurias ; complications ; diagnosis ; epidemiology

OBJECTIVETo identify the mutation spectrum and the distribution of minihaplotypes (STR/VNTR) of phenylalanine hydroxylase (PAH) gene and explore the correlations between genotype and phenotype of patients with phenylketonuria (PKU) in Beijing area of China.

METHOD(1) Fifty cases with PKU were involved in this study. PKU was identified by the Neonatal Screening Center of Beijing. All 13 exons and their flanking intronic sequences of PAH gene of these patients were amplified and then subjected to SSCP analysis and direct sequencing. (2) The distribution of polymorphic locus of short tandem repeat (STR) and variable number tandem repeat (VNTR) was analyzed by PCR and denaturing gel electrophoresis. (3) The correlations between genotype and phenotype were studied by analysis of the matching rate between the expected and observed phenotypes. The predicted phenotype was determined on the basis of the sum of the assigned values of the two mutant alleles.

RESULTS(1) A total of 34 different mutations were detected with the relative frequency of 95% among 50 PKU patients. The prevalent mutations in this study were: R243Q (20%), EX6-96A > G (11%), Y356X (9%), and V399V (7%). The next common mutations were R111X (5%), R413P (5%), R252Q (3%) and A434D (3%). Thirty-four detected mutations were distributed throughout the whole PAH gene, except exon 1, 8 and 13. Exon 7 and 11, with the mutant rate 34% and 19% respectively, seemed to be the hot mutant areas/regions of PAH gene. (2) The minihaplotypes (STR/VNTR) of 34 mutations were identified in this research. The STR and VNTR showed 8 and 3 alleles, respectively. Among them, 244 bp (44%) and 240 bp (34%) were the prevalent STR alleles. Meanwhile, the VNTR3 (83%) was the most common VNTR allele in PKU patients. (3) A better consistency (81.5%) between expected and observed phenotypes was revealed by analysis of correlation between genotype and phenotype. Especially in classic PKU, the consistency rate was up to 87.5%.

CONCLUSION(1) The frequency distribution of common PAH gene mutations in Beijing region was close to that of Tianjin and Yunnan regions, while it was different from that of Southern regions of China, such as Guangzhou, especially Taiwan. The PAH mutation with a highly heterogeneous trait was also demonstrated in this study. (2) STR and VNTR minihaplotype will prove helpful to trace the origins of PAH mutations and to analyze the genetic drift. However, the most minihaplotypes of the STR/VNTR are similar, so it is necessary to associate some other polymorphic loci with the STR/VNTR minihaplotype to analyze the different mutations. (3) The fact that a better consistency existed between phenotypes and genotype with most PKU patients suggested that the study of the genotype of PKU patients would be helpful to the individualized treatment and to genetic counseling for their families.

Alleles ; China ; epidemiology ; Genetic Association Studies ; Genotype ; Humans ; Infant, Newborn ; Introns ; Mutation ; Phenotype ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; epidemiology ; genetics ; Polymorphism, Genetic

OBJECTIVETo investigate the incidence of hyperphenylalaninemia (HPA) caused by different etiologic factors in China and the relationship between the phenylalanine and mental development of patients with HPAs who were diagnosed by neonatal screening and early treated.

METHODSTwo hundred and twenty-three patients with HPA detected by neonatal screening programs were refered to us at the age of (41 +/- 27) days after birth. The differential diagnosis was performed by BH(4) (20 mg/kg) loading test, urinary pterin analysis and dihydropteridine reductase (DHPR) activity determination respectively. The control of phenylalanine (Phe) metabolism, growth and mental development were evaluated in all treated patients. Related gene mutation analysis was performed in some patients

RESULTSOne hundred and twenty-nine of 223 patients (57.8%) were diagnosed as phenylalanine hydroxylase deficiency (PAHD), 64 patients (28.7%) as BH(4) responsive PAHD, 30 patients (13.5%) as 6-pyruvoyl tetrahydropterin synthase deficiency (PTSD). One hundred and forty-nine patients were followed at age of 4 m - 2 y in our clinic. The 136 of 149 patients were treated according to different etiology at the age of 1.6 m (0.5 - 3.5 m) after birth. Thirteen patients were followed up without the need for treatment. All patients had normal growth development. One hundred and eight (79.4%) of 136 treated patients had normal mental development. The negative correlation (r = -0.439, P < 0.01) between IQ and average Phe levels were observed in 58 patients. Twenty-eight patients were able to go to primary school or even university. Nine kinds of PTS gene mutations were found in 9 cases with PTSD, among which 286G-->A and 259C-->T were most commonly seen, accounting for 45%. Seven kinds of PAH gene mutations were found in 13 cases with BH(4) responsive PAHD with the R241C (43.8%) mutation being the most frequent one.

CONCLUSIONThe differential diagnosis should be quickly made in all HPA patients detected by neonatal screening. Near 80% patients early treated had normal mental development. The good control of blood Phe level is a key factor for mental development.

China ; epidemiology ; Female ; Follow-Up Studies ; Humans ; Incidence ; Infant ; Infant, Newborn ; Male ; Neonatal Screening ; methods ; Phenylalanine ; blood ; Phenylketonurias ; diagnosis ; epidemiology ; prevention & control ; Time Factors

OBJECTIVETo analyze the results of screening for neonatal phenylketonuria (PKU) in Zhejiang Province.

METHODSThe screening for neonatal PKU was conducted among 726,998 newborns in Zhejiang Province. Heel prick blood specimens were collected around 72 h after birth with 6 intakes of high protein milk and the specimens were dried on S and S903 filter papers. Phenylalanine (Phe) levels were determined quantitatively with Perkin Elmer Neonatal Fluorometric PKU kits.

RESULTSAmong 726,998 newborns, elevated blood Phe levels were found in 152 infants. They were all recalled for serum amino acid analysis and 32 were confirmed to have PKU with 19 males and 13 females. The earliest time of confirmation was 16 d and latest was 105 d with the median of 32 d.

CONCLUSIONThe data shows that the detection rate of screening for neonatal phenylketonuria in Zhejiang Province was 1/22,718.

China ; epidemiology ; Female ; Humans ; Incidence ; Infant, Newborn ; Male ; Neonatal Screening ; Phenylalanine ; blood ; Phenylketonurias ; epidemiology ; prevention & control

OBJECTIVESTo summarize neonatal screening for phenylketonuria (PKU) and congenital hypothyroidism (CH) in China, to further clarify incidence of the two kinds of diseases in newly-born babies, and to explore issues in neonatal screening and their solutions.

METHODSNeonatal screening for PKU and CH was conducted by 39 neonatal screening centers all over the country, sponsored by the Group of Neonatal Screening, Chinese Society of Child Health Care, Chinese Preventive Medical Association and the Center for Neonatal Screening Quality Control Laboratory, National Center for Clinical Laboratories (NCCL). In each infant a heel prick blood sample was collected at 72 hours postnatal onto standard filter paper. PKU was screened by bacterial inhibition assay and fluorometric method, and CH was screened by TSH measurement by time-resolved fluorescence immunoassay (TRFIA), fluorescence enzyme immunoassay (FEIA) and enzyme immunoassay (EIA).

RESULTSFrom 1985 to 2001 in China, totally of 5 817 280 newborns were screened for PKU, 522 cases of PKU detected with an incidence of 1:11 144, and 5 524 019 newborns were screened for CH, 1 836 cases of CH detected with an incidence of 1:3 009. Annual average number of newborns screened for congenital genetic diseases was increased by 45.5% in recent six years.

CONCLUSIONSNeonatal screening was developed quickly in China in recent years, especially in some developed cities, such as Shanghai with a coverage of 98.3% in 2001. But, its coverage was about only 10% in China as a whole. In development of neonatal screening, it is necessary to attach more importance to quality of screening and increasing coverage of screening, as well as gradual development of new screening techniques for other neonatal preventable diseases, in addition to PKU and CH, and their application, and improvement of level of child health care in China.

China ; epidemiology ; Congenital Hypothyroidism ; Fluorescence Polarization Immunoassay ; Fluorometry ; Humans ; Hypothyroidism ; epidemiology ; Immunoenzyme Techniques ; Infant, Newborn ; Neonatal Screening ; Phenylketonurias ; epidemiology ; Thyrotropin ; blood