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 <i>PAHi> 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 <i>PAHi> gene can improve the genetic diagnostic rate of PKU. The development of targeted detection kits for <i>PAHi> 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

Case 1: A 19-day-old male infant presented with poor feeding and decreased activity for 2 weeks, worsening with poor responsiveness for 3 days. At 5 days old, he developed poor feeding and poor responsiveness, was hospitalized, and was found to have elevated blood ammonia and thrombocytopenia. Whole-genome genetic analysis revealed a pathogenic homozygous mutation in the <i>PCCAi> gene, NM-000282.4: c.1834-1835del (p.Arg612AspfsTer44), leading to a diagnosis of propionic acidemia. Case 2: A 4-day-old male infant presented with poor responsiveness and feeding difficulties since birth, with elevated blood ammonia for 1 day. He showed weak sucking and deteriorating responsiveness, with blood ammonia >200 µmol/L. Genetic testing identified two heterozygous mutations in the <i>MMUTi> gene: NM_000255.4: c.1677-1G>A and NM_000255.4: ex.5del, confirming methylmalonic acidemia. Case 3: A 20-day-old male infant presented with poor feeding for 15 days and skin petechiae for 8 days. He developed feeding difficulties at 5 days old and lower limb petechiae at 12 days old, with blood ammonia measured at 551.6 µmol/L. Genetic analysis found two heterozygous mutations in the <i>PCCAi> gene: NM_000282.4: c.1118T>A (p.Met373Lys) and NM_000282.4: ex.16-18del, confirming propionic acidemia. In the first two cases, continuous hemodiafiltration was performed for 30 hours and 20 hours, respectively, before administering carglumic acid. In the third case, carglumic acid was administered orally without continuous hemodiafiltration, resulting in a decrease in blood ammonia from 551.6 µmol/L to 72.0 µmol/L within 6 hours, with a reduction rate of approximately 20-25 µmol/(kg·h), similar to the first two cases. Carglumic acid was effective in all three cases, suggesting it may help optimize future treatment protocols for organic acidemia.
Humans ; Male ; Infant, Newborn ; Propionic Acidemia/drug therapy* ; Amino Acid Metabolism, Inborn Errors/genetics* ; Mutation ; Methylmalonyl-CoA Decarboxylase/genetics* ; Citrates/administration & dosage* ; Carbon-Carbon Ligases/genetics* ; Glutamates

OBJECTIVES: To investigate the growth parameters of children with phenylketonuria and assess the impact of a phenylalanine-restricted diet on their physical development. METHODS: The study involved 39 children diagnosed with phenylketonuria through newborn screening at the Central Child Teaching Hospital, Baghdad, Iraq. Data were collected during scheduled monthly check-ups, including phenylalanine levels, diet compliance, and anthropometric measurements. The children were divided into two groups based on their phenylalanine levels during the 3-year follow-up period: well-controlled group (average phenylalanine level of less than 360 μmol/L, with no single reading exceeding 600 μmol/L; <i>ni>=14) and poorly-controlled group (one or more phenylalanine readings above 600 μmol/L during the follow-up period; <i>ni>=25). RESULTS: The mean height readings for all time points (at birth and 3, 6, 9, 12, 15, 18, 21, 24 and 36 months of age) were higher in the well-controlled group than the poorly-controlled group, however, only at 3 months of age the difference was statistically significant. Height Z-scores revealed a clearer pattern: although the poorly-controlled group had higher height Z-scores at birth (<i>Pi>=0.001), the well-controlled group showed significantly higher height Z-scores at 3, 6, 12, 15, 18, 24, and 36 months (<i>Pi><0.05). The well-controlled group exhibited significantly higher mean weight measurements compared to the poorly-controlled group at 3, 6, 9, 15, 18 months and 21 months (<i>Pi><0.05). From 6 to 36 months, the well-controlled group consistently had significantly higher weight Z-scores than the poorly-controlled group (<i>Pi><0.05). The well-controlled group showed more favorable height and weight Z-score distributions at 36 months of age compared to the poorly-controlled group, but the differences were not statistically significant (<i>Pi>>0.05). Both groups had height and weight Z-scores within the normal range at 36 months of age. CONCLUSIONS The children with phenylketonuria who receive good dietary control show better improvements in growth parameters compared to those with poor dietary control, however, both groups maintain height and weight Z-scores within the normal range, indicating generally adequate physical development across the cohort.
Humans ; Phenylketonurias/diet therapy* ; Male ; Female ; Child, Preschool ; Infant ; Body Height ; Infant, Newborn ; Child Development ; Phenylalanine/blood*

OBJECTIVE: To explore the results of four types of Urea cycle disorders (UCDs) in newborns from the Xuzhou region, assess the efficacy of newborn screening by tandem mass spectrometry (MS/MS), and analyze their genetic characteristics. METHODS: A retrospective analysis was performed using tandem mass spectrometry to screen for inherited metabolic disorders in 691 712 newborns at the Maternal and Child Health Care Hospital of Xuzhou from November 2015 to December 2023. Ten children (cases 1-10) were diagnosed with Ornithine transcarbamylase deficiency (OTCD), Carbamoylphosphate synthase 1 deficiency (CPS1D), Arginase deficiency (ARGD), and Argininosuccinate synthase deficiency (ASSD) based on MS/MS and genetic testing. This study was approved by the Medical Ethics Committee of Xuzhou Maternity and Child Health Care Hospital (Ethics No.XZFY2024-051K-01J). RESULTS: A total of 691 712 neonates were screened for UCDs using MS/MS, which identified 1 237, 1 237, 510, and 1 009 initial positive cases for OTCD, CPS1D, ASSD, and ARGD, respectively. After genetic testing, 1 case of OTCD, 1 case of CPS1D, 1 case of ASSD, and 7 cases of ARGD were confirmed. The overall positive predictive value for these four UCDs was 0.362%. Among the 10 diagnosed UCD cases, four novel variants were identified, which included OTC: c.1024C>A (p.L342M) and ASS1: c.826A>G (p.M276V), c.695C>T (p.P232L) and c.694C>T (p.P232S). Bioinformatic analysis has rated these as variants of uncertain clinical significance or likely pathogenic based on guidelines from the American College of Medical Genetics and Genomics (ACMG). CONCLUSION The incidence of four UCDs in neonates from the Xuzhou area is relatively low, and there is a correlation between genetic variants and clinical phenotypes. For novel variants with uncertain clinical significance or suspected pathogenicity, their pathogenicity should be clarified in conjunction with clinical and biochemical indicators. The four novel pathogenic variants of UCDs identified in this study have enriched the mutational spectrum of UCDs-associated genes in the Xuzhou region.
Humans ; Infant, Newborn ; Tandem Mass Spectrometry/methods* ; Urea Cycle Disorders, Inborn/diagnosis* ; Neonatal Screening/methods* ; Genetic Testing/methods* ; Female ; Retrospective Studies ; Male ; Ornithine Carbamoyltransferase Deficiency Disease/diagnosis* ; Mutation ; Carbamoyl-Phosphate Synthase (Ammonia)/genetics* ; Ornithine Carbamoyltransferase/genetics*

OBJECTIVE: To explore the incidence, clinical features, genetic variant characteristics and prognosis of Glutaric acidemia type I (GA1) among neonates from Henan Province. METHODS: A total of 814 625 neonates undergoing screening for inherited metabolic diseases by tandem mass spectrometry (MS/MS) at the Third Affiliated Hospital of Zhengzhou University from January 2016 to December 2022 were selected as the study subjects. A retrospective method was adopted to collect the clinical data of the patients. Whole exome sequencing was carried out to detect GCDH gene variants in individuals with positive results by GA1 newborn screening, and Sanger sequencing was used to verify the candidate variants. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the pathogenicity of candidate variants was rated. This study was approved by the Medical Ethics Committee of the Hospital (Ethics Number: 2019 Medical Ethics Review No. 67). RESULTS: Eight cases of GA1 were diagnosed among the 814 625 neonates. Blood glutaryl carnitine (C5DC) and urine glutaric acid (GA) levels of the 8 children were higher than the normal reference values. In total 12 variants were detected, all of which were missense variants. c.1064G>A (p.Arg355His) was the most common one, accounting for 21.4% (3/14). Three GCDH gene variants, including 1297G>C (p.Ala433Pro), c.467G>A (p.Gly156Asp) and c.1125T>G (p.Cys375Trp), were previously unreported. REVEL software analysis predicted that all of the three variants were harmful. 3D protein structure modeling indicated that the three variants may cause amino acid residue alterations, and c.1297G>C (p.Ala433Pro) and c.1125T>G (p.Cys375Trp) may result in increase in hydrogen bonds and affect the function of GCDH protein. By December 2023, one of the eight children had deceased, and another child had severe clinical symptoms with poor prognosis. Six children had a good prognosis, of which two had mild motor development delay and four had normal development without clinical symptoms. CONCLUSION The incidence of GA1 in newborns screened by MS/MS in Henan Province is 1/101 828, and the carrier rate of pathogenic GCDH variants is 1/160. The c.1064G>A (p.Arg355His) may be the hotspot variant of the GCDH gene among children with GA1 in Henan. Discovery of the three novel variants has enriched the mutational spectrum of the GCDH gene and provide a basis for the early diagnosis, treatment, prognosis and genetic counseling of this disease.
Humans ; Amino Acid Metabolism, Inborn Errors/epidemiology* ; Glutaryl-CoA Dehydrogenase/chemistry* ; Infant, Newborn ; Female ; Neonatal Screening/methods* ; Male ; Brain Diseases, Metabolic/epidemiology* ; China/epidemiology* ; Retrospective Studies ; Mutation ; Genetic Variation ; Glutarates

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

Hyperphenylalaninemia (HPA) is an inherited metabolic disorder caused by deficiency of phenylalanine hydroxylase, characterized by significantly elevated phenylalanine levels. Conventional mechanisms, such as neurotransmitter deficiency and dysmyelination, fail to fully explain the progressive neurological damages associated with HPA. Meanwhile, ferroptosis, an emerging form of iron-dependent regulated cell death, has proven to play an important role in neurodegenerative diseases. We hereby propose a hypothesis that tetrahydrobiopterin (BH4) depletion in HPA may lead to the collapse of intracellular antioxidant defenses. This process could induce ferroptosis, thereby serving as a pivotal mechanism underlying HPA-related neurological injury. This review has systematically summarized the pathological mechanisms of HPA, the biological features of ferroptosis, and the bridging role of BH4 between them, thereby establishing a novel "HPA-BH4-ferroptosis" theoretical framework and providing a rationale for developing new therapeutic strategies targeting ferroptosis.
Ferroptosis ; Humans ; Biopterins/deficiency* ; Phenylketonurias/pathology* ; Animals

Humans ; Propionic Acidemia/complications* ; Cardiomyopathy, Dilated/etiology*

Humans ; Amino Acid Metabolism, Inborn Errors/genetics* ; Haploinsufficiency

OBJECTIVE: To investigate the clinical manifestations, biochemical abnormalities and pathogenic variants among children with Short/branched-chain acyl-CoA dehydrogenase (SBCAD) deficiency detected by neonatal screening. METHODS: A total of 2 730 852 newborns were screened from January 2016 to December 2021 with liquid chromatography tandem mass spectrometry. Suspected SBCAD deficiency patients were diagnosed by urine organic acid analysis and high-throughput gene sequencing analysis. The clinical, biochemical and genetic changes of the confirmed cases were analyzed, in addition with guidance for diet and life management, L-carnitine supplement, and survey of growth and intellectual development. RESULTS: Twelve cases of SBCAD deficiency were diagnosed, which yielded a prevalence of 1/227 571. The lsovaleryl carnitine (C5) of primary screening blood samples was between 0.6 and 2.1 µmol/L, all exceeded the normal range. C5/acety1 carnitine (C2) was between 0.02 and 0.12, with 6 cases exceeding the normal range. C5/propionyl carnitine (C3) was between 0.1 and 1.16, with 5 cases exceeding the normal range. Free carnitine (C0) was between 18.89 and 58.12 µmol, with 1 case exceeding the normal range. Three neonates with abnormal screening results were recommended to have appropriate restriction for protein intake and two were given L-carnitine. During follow-up, their C5 has ranged from 0.22 to 2.32 µmol/L, C5/C2 has ranged from 0.01 to 0.31, C5/C3 has ranged from 0.14 to 1.7. C5 or C5/C2 and C5/C3 were transiently normal in all patients except for case 8 during the neonatal screening and follow-up. C0 was 17.42 ∼ 76.83 µmol/L Urine organic acid analysis was carried out in 9 of the 12 cases, and 2-methylbutyroglycine was elevated in 8 cases. Urine organic acid analysis was carried out in 9 cases, and 2-methylbutyrylglycine was increased in 8 cases. Genetic analysis was carried out for 11 children, and in total 6 ACADSB gene variants were identified, which included 4 missense variants (c.655G>A, c.923G>A, c.461G>A, c.1165A>G), 1 frameshift variant (c.746del) and 1 nonsense variant (c.275C>G). Among these, the C.461G>A variant was unreported previously. The most common variants were c.1165A>G (40.9%) and C.275C>G (22.7%). The patients were followed up for 18 days to 55 months. Only one patient had mental retardation, with the remainders having normal physical and mental development. CONCLUSION SBCAD deficiency is a rare disease. The detection rate of newborn screening in this study was 1/227 571. Early intervention can be attained in most asymptomatic patients through neonatal screening. In this study, the common gene variants are c.1165A>G and c.275C>G.
Humans ; Infant, Newborn ; Amino Acid Metabolism, Inborn Errors/genetics* ; Carnitine ; Neonatal Screening/methods*