Objective:To explore the genetic basis of eighteen patients with tetrahydrobiopterin deficiency (BH4D) from Gansu Province.Methods:Eighteen patients diagnosed with BH4D at Gansu Provincial Maternal and Child Health Care Hospital from January 2018 to December 2021 were selected as the study subjects. Whole exome sequencing was carried out, and candidate variants were verified by Sanger sequencing.Results:All of the thirty-six alleles of the eighteen patients were successfully determined by molecular genetic testing. Sixteen patients were found to harbor variants of the PTS gene, and two had harbored variants of the QDPR gene. Ten variants were detected in the PTS gene, with the most common ones being c. 259C>T (34.38%) and c. 286G>A (15.63%). Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c. 259C>T was classified as a pathogenic variant, whilst the c. 286G>A, c. 166G>A, c. 200C>T, c. 272A>G, c. 402A>C, c. 421G>T, c. 84-291A>G and c. 317C>T were classified as likely pathogenic variants. A novel c. 289_290insCTT variant was classified as likely pathogenic (PM1+ PM2_Supporting+ PM3+ PP3+ PP4). The two variants (c.478C>T and c. 665C>T) detected in the QDPR gene were both classified as variants of uncertain significance (PM1+ PM2_Supporting+ PP3+ PP4). Conclusion:Genetic testing has clarified the pathogenic variants in these BH4D patients, which has enabled timely and accurate clinical intervention and treatment, and provided a reference for genetic counseling and reproductive guidance for their families.

Objective:To explore the genetic basis for a Chinese pedigree affected with co-morbid Ornithine carbamoyl transferase deficiency (OTCD) and MECP2 duplication syndrome.Methods:A proband who was admitted to the Neonatal Intensive Care Unit of Gansu Provincial Maternal and Child Health Care Hospital on December 19, 2017 was selected as the study subject. High-throughput sequencing and multiplex ligation-dependent probe amplification (MLPA) were carried out for her pedigree, and short tandem repeat-based linkage analysis and chromosome copy number variation sequencing (CNV-seq) were used for the prenatal diagnosis.Results:The proband, a 3-day-old female, was found to harbor heterozygous deletion of exons 7-9 of the OTC gene. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as likely pathogenic (PVS1+ PM2_Supporting+ PP4). The proband was diagnosed with OTCD, which was in keeping with her acute encephalopathy and metabolic abnormalities (manifesting as hyperammonemia, decreased blood citrulline, and increased urine orotic acid). Prenatal diagnosis was carried out for the subsequent pregnancy. The fetus did not harbor the exons 7-9 deletion of the OTC gene, but was found to carry a duplication in Xq28 region (which encompassed the whole region of MECP2 duplication syndrome) and was positive for the SRY sequence. The same duplication was also found in the proband and her mother. Considering the possible existence of X-chromosome inactivation, the proband was diagnosed with two X-linked recessive disorders including OTCD and MECP2 duplication syndrome, and the fetus was determined as a male affected with the MECP2 duplication syndrome. Conclusion:Discoveries of the pathogenic variants underlying the OTCD and MECP2 duplication syndrome have enabled clinical intervention, treatment, genetic counseling and prenatal diagnosis for this pedigree.

Objective:To explore the genetic basis for a patient with autosomal dominant retinitis pigmentosa (RP).Methods:A male patient with RP treated at Gansu Provincial Maternal and Child Health Care Hospital in September 2019 was selected as the study subject. Clinical data was collected. Peripheral blood samples of the patient and his parents were subjected to whole exome sequencing (WES). Candidate variant was validated by Sanger sequencing and bioinformatic analysis.Results:The patient, a 29-year-old male, developed night blindness, amblyopia, visual field defects and optic disc abnormalities since childhood. Gene sequencing revealed that he has harbored a heterozygous c. 942G>C (p.Lys314Asn) variant of the IMPDH1 gene, which was inherited from his mother, whilst his father was of the wild type. Based on the guidelines from the American College of Medical Genetics and Genomics, the c. 942G>C variant was predicted as likely pathogenic (PM1+ PM2_Supporting+ PP3+ PP1). Conclusion:The c. 942G>C (p.Lys314Asn) variant in the IMPDH1 gene probably underlay the RP in this patient.

Objective:To analyze the clinical phenotype and genotypes of two children with Carnitine-acylcarnitine translocase deficiency (CACTD).Methods:Two children diagnosed with CACTD at the Gansu Provincial Maternal and Child Health Care Hospital respectively on January 3 and November 19, 2018 were selected as the study subjects. Trio-whole exome sequencing (trio-WES) was carried out, and candidate variants were validated through Sanger sequencing and pathogenicity analysis.Results:Both children were males and had manifested mainly with hypoglycemia. Trio-WES and Sanger sequencing showed that child 1 had harbored compound heterozygous variants of the SLC25A20 gene, namely c. 49G>C (p.Gly17Arg) and c. 106-2A>G, which were inherited from his father and mother, respectively. Child 2 had harbored homozygous c. 199-10T>G variants of the SLC25A20 gene, which were inherited from both of his parents. Among these, the c. 106-2A>G and c. 49G>C variants were unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c. 49G>C (p.Gly17Arg), c. 106-2A>G, and c. 199-10T>G variants were classified as likely pathogenic (PM2_supporting+ PP3+ PM3_strong+ PP4), pathogenic (PVS1+ PM2_supporting+ PM5+ PP3), and pathogenic (PVS1+ PM2_supporting+ PP3+ PP5), respectively. Conclusion:Combined with their clinical phenotype and genetic analysis, both children were diagnosed with CACTD. Above finding has provided a basis for their treatment as well as genetic counseling and prenatal diagnosis for their families.

OBJECTIVE: To explore the genetic etiology for a fetus with Walker-Warburg syndrome(WWS). METHODS: A fetus with WWS diagnosed at Gansu Provincial Maternity and Child Health Care Hospital in June 9, 2021 was selected as the study subject. Genomic DNA was extracted from amniotic fluid sample of the fetus and peripheral blood samples from its parents. Trio-Whole exome sequencing (trio-WES) was carried out. Candidate variants were verified by Sanger sequencing. RESULTS: The fetus was found to harbor compound heterozygous variants of the POMT2 gene, namely c.471delC (p.F158Lfs*42) and c.1975C>T (p.R659W), which were respectively inherited from its father and mother. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), they were respectively rated as pathogenic (PVS1+PM2_Supporting+PP4) and likely pathogenic (PM2_Supporting+PM3+PP3_Moderate+PP4). CONCLUSION Trio-WES may be used for the prenatal diagnosis of WWS. The compound heterozygous variants of the POMT2 gene probably underlay the disorder in this fetus. Above finding has expanded the mutational spectrum of the POMT2 gene and enabled definite diagnosis and genetic counseling for the family.
Pregnancy ; Child ; Female ; Humans ; Walker-Warburg Syndrome ; Prenatal Diagnosis ; Fetus ; Genetic Counseling ; Genomics ; Mutation

OBJECTIVE: To explore the genetic etiology of a child with Pitt-Hopkins syndrome. METHODS: A child who had presented at the Medical Genetics Center of Gansu Provincial Maternal and Child Health Care Hospital on February 24, 2021 and his parents were selected as the study subjects. Clinical data of the child was collected. Genomic DNA was extracted from peripheral blood samples of the child and his parents and subjected to trio-whole exome sequencing (trio-WES). Candidate variant was verified by Sanger sequencing. Karyotype analysis was also carried out for the child, and her mother was subjected to ultra-deep sequencing and prenatal diagnosis upon her subsequent pregnancy. RESULTS: The clinical manifestations of the proband included facial dysmorphism, Simian crease, and mental retardation. Genetic testing revealed that he has carried a heterozygous c.1762C>T (p.Arg588Cys) variant of the TCF4 gene, for which both parents had a wild-type. The variant was unreported previously and was rated as likely pathogenic based on the guidelines of the American College of Medical Genetics and Genomics (ACMG). Ultra-deep sequencing indicated that the variant has a proportion of 2.63% in the mother, suggesting the presence of low percentage mosaicism. Prenatal diagnosis of amniotic fluid sample suggested that the fetus did not carry the same variant. CONCLUSION The heterozygous c.1762C>T variant of the TCF4 gene probably underlay the disease in this child and has derived from the low percentage mosaicism in his mother.
Child ; Female ; Humans ; Male ; Pregnancy ; Intellectual Disability/genetics* ; Mosaicism ; Mothers ; Mutation ; Parents ; Transcription Factor 4/genetics*

OBJECTIVE: To analyze the clinical phenotype and results of genetic testing in three children with Cornelia de Lange syndrome (CdLS). METHODS: Clinical data of the children and their parents were collected. Peripheral blood samples of the pedigrees were collected for next generation sequencing analysis. RESULTS: The main clinical manifestations of the three children have included growth delay, mental retardation, peculiar facies and other accompanying symptoms. Based on the criteria proposed by the International Diagnostic Consensus, all three children were suspected for CdLS. As revealed by whole exome sequencing, child 1 has harbored NIPBL gene c.5567_5569delGAA insTAT missense variant, child 2 has harbored SMC1A gene c.607A>G missense variant, and child 3 has harbored HDAC8 gene c.628+1G>A splicing variant. All of the variants were de novo in origin. CONCLUSION All of the children were diagnosed with CdLS due to pathogenic variants of the associated genes, among which the variants of NIPBL and HDAC8 genes were unreported previously. Above finding has enriched the spectrum of pathogenic variants underlying CdLS.
Humans ; Cell Cycle Proteins/genetics* ; De Lange Syndrome/diagnosis* ; Genotype ; Phenotype ; Genetic Testing ; Histone Deacetylases/genetics* ; Repressor Proteins/genetics*

OBJECTIVE: To analyze the clinical phenotype and genetic basis for a child with acute form of tyrosinemia type I (TYRSN1). METHODS: A child with TYRSN1 who presented at the Gansu Provincial Maternal and Child Health Care Hospital in October 2020 was selected as the subject. The child was subjected to tandem mass spectrometry (MS-MS) and urine gas chromatography-mass spectrometry (GC-MS) for the detection of inherited metabolic disorders, in addition with whole exome sequencing (WES). Candidate variants were validated by Sanger sequencing. RESULTS: The child's clinical features included abdominal distension, hepatomegaly, anemia and tendency of bleeding. By mass spectrometry analysis, her serum and urine tyrosine and succinylacetone levels have both exceeded the normal ranges. WES and Sanger sequencing revealed that she has harbored c.1062+5G>A and c.943T>C (p.Cys315Arg) compound heterozygous variants of the FAH gene, which were inherited from her father and mother, respectively. Among these, the c.943T>C was unreported previously. CONCLUSION Considering her clinical phenotype and result of genetic testing, the child was diagnosed with TYRSN1 (acute type). The compound heterozygous variants of the FAH gene probably underlay the disease in this child. Above finding has further expanded the spectrum of FAH gene variants, and provided a basis for accurate treatment, genetic counseling and prenatal diagnosis for her family.
Female ; Humans ; Gas Chromatography-Mass Spectrometry ; Genetic Testing ; Mutation ; Phenotype ; Prenatal Diagnosis ; Tyrosinemias/genetics* ; Child

OBJECTIVE: To explore the clinical features and genetic basis for a child with 3-methylglutaconic aciduria type VII. METHODS: A child who was diagnosed at the Gansu Provincial Maternity and Child Health Care Hospital on August 9, 2019 was selected as the study subject. Clinical data of the child, including urine gas chromatography and mass spectrometry, were collected. The child and her parents were subjected to whole exome sequencing. RESULTS: The child, a female neonate, had presented mainly with intermittent skin cyanosis, convulsions, hypomagnesemia, apnea, neutropenia after birth. Her urine 3-methylpentenedioic acid has increased to 17.53 μmol/L. DNA sequencing revealed that she has harbored compound heterozygous variants of the CLPB gene, namely c.1016delT (p.L339Rfs*5) and c.1087A>G (p.R363G), which were respectively inherited from her mother and father. Both variants were unreported previously. Based on the standards from the American College of Medical Genetics and Genomics (ACMG), the variants were respectively predicted to be pathogenic and likely pathogenic. CONCLUSION The child was diagnosed with 3-methylglutenedioic aciduria type VII. Discovery of the c.1016delT and c.1087A>G variants has enriched the mutational spectrum of the CLPB gene.
Female ; Humans ; Infant, Newborn ; Pregnancy ; Base Sequence ; Metabolism, Inborn Errors/diagnosis* ; Mutation ; Neutropenia/genetics* ; Sequence Analysis, DNA

Objective:To summarize the clinical features and gene variations in children with Townes-Brocks syndrome (TBS).Methods:The clinical data of a female infant diagnosed with TBS caused by human spalt-like transcription factor 1 ( SALL1) gene mutation in Gansu Maternal and Child Health Hospital in May 2022 were analyzed retrospectively. Relevant articles up to July 2022 were retrieved from several databases including CNKI, VIP, Wanfang, Chinese Medical Journal Network and PubMed with the terms of " SALL1 gene" and "Townes-Brocks syndrome". Patients diagnosed with TBS caused by SALL1 gene mutation were retrieved and the clinical phenotype-genotype correlations in patients with TBS caused by frameshift mutation in SALL1 gene were analyzed and summarized. Descriptive statistical analysis was applied. Results:(1) Clinical data: The index patient was a 40-day-old girl exhibiting major clinical manifestations of polycystic kidney dysplasia, congenital external ear deformity, preaxial polydactyly and recto-perineal fistula. Whole exome sequencing and Sanger sequencing revealed a heterozygous variation of c.420delC (p.S141fs*42) in the SALL1 gene, while the same gene was found to be wild type in her parents and sister. The variant was predicted to be pathogenic (PVS1+PS2+PM2). (2) Literature review retrieved 161 cases of TBS, of which 71 were attributable to a frameshift mutation in SALL1 gene. Clinical phenotypes of the 71 cases and the index case were summarized. TBS was mainly characterized by external ear, hand and anal deformities, sometimes accompanied by hearing loss, abnormal kidney development and foot deformity. A small number of affected cases presented with rare clinical phenotypes such as abnormal eyes, hypothyroidism and abnormal development. At present, the human gene mutation database records 110 variations in the SALL1 gene, with a majority located in exon 2. The most common mutation type was frameshift variation, accounting for 52%, followed by missense variation and nonsense variation. Conclusion:TBS should be considered in children with ear, hand and anal malformations, accompanied by renal dysfunction and hearing loss, and genetic testing is recommended for timely diagnosis.