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 characteristics of a child with comorbid 16p11.2 microdeletion syndrome and Rett syndrome (RTT).Methods:A male infant who was admitted to Gansu Provincial Maternity and Child Health Care Hospital in May 2020 was selected as the study subject. Clinical data of the infant was collected. Genomic DNA was extracted from peripheral blood samples from the infant and his parents, and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing.Result:The patient, a 4-day-old male infant, had presented with poor response, poor intake, feeding difficulties, and deceased at 8 months after birth. WES revealed that he has harbored a 0.643 Mb deletion in the 16p11.2 region, which encompassed key genes of the 16p11.2 microdeletion syndrome such as ALDOA, CORO1A, KIFF22, PRRT2 and TBX6. His father has carried the same deletion, but was phenotypically normal. The deletion was predicted to be pathogenic. The child was also found to harbor a maternally derived c. 763C>T (p.R255X) hemizygous variant of the MECP2 gene, which was also predicted to be pathogenic (PVS1+ PS4+ PM2_Supporting). Conclusion:The 16p11.2 deletion and the MECP2: c.763C>T (p.R255X) variant probably underlay the pathogenesis in this infant.

Objective To perform genetic analysis in a family line of a pregnant couple with autosomal reces-sive non-syndromic deafness in order to identify its possible genetic etiology and provide prenatal diagnosis.Methods Whole-exome sequencing(WES)was used to analyze the genes of the proband,and Sanger sequencing was used to verify the suspected pathogenic loci.Prenatal genetic diagnosis was performed after amniotic fluid collection at 18 weeks of pregnancy.Results Autosomal recessive deafness type 3 related gene MYO15A c.10419_10423delCAGCT/c.10294_10308delCCTTGCATCCTTGCC compound heterozygous variant was found in the wife.A compound heterozygous variant of autosomal recessive deafness type 77-related gene LOXHD1:c.6388C＞T/ex-on 33-38 del.Maternal MYO15A c.10294_10308del CCTTGCATCCTTGCC heterozygous variant were detected in the husband and paternal LOXHD1 exon 33-38 del heterozygous variant were detected in the fetus.At the same time,the paternal CDH23 c.6693delT heterozygous mutation and the maternal PCDH15 c.5048_5051dupAGAA heterozygous mutation were detected in the fetus.These two heterozygous mutations lead to the possibility of the fe-tus suffering from ID/F Usher syndrome.Conclusion The deafness of the couple is caused by two different deaf gene mutations,and the probability of the fetus having the same deafness as the couple is very low.However,the fetus has a high possibility of having deafness caused by two gene mutations.Therefore,deafness caused by two gene mutations should be paid attention to in the prenatal diagnosis of families with both deaf parents.

We retrospectively analyzed a child with early-onset globoid cell leukodystrophy(Krabbe's disease)caused by complex heterozygous variations in the GALC gene.The girl was admitted to the hospital at the age of 4 month with main complaints of"No obvious cause of milk refusal,poor mental state,drowsiness,convulsions,fever."Brain MRI showed abnormal symmetric signals changes in bilateral cerebellar hemispheres,bilateral internal capsule hind limbs and bilateral ventricles,thin corpus callosum,myelination process lags behind the level of children of the same age.High-throughput sequencing analysis identified compound heterozygous mutations in GALC gene(NM 000153.4):c.[908+1G>A];[194G>A and the two heterozygous mutations were correspondingly inherited from his father and mother,respectively.The application of high-throughput sequencing technology can diagnose Krabbe disease efficiently and accurately,which assists in clinical identification and diagnosis.

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.

Objective:To observe and determine the gene mutation site and clinical phenotype of a NDP gene mutant family, and provide a basis for the prenatal diagnosis of offspring. Methods:A pedigree investigation study. Two patients and 6 family members of a third-generation Han family with NDP gene mutation who were admitted to the Maternal and Child Health Hospital of Gansu Province from July 2019 to December 2021 were included in the study. The patients and their parents underwent the examination of pupil light reflex, strip light imaging, visual acuity evaluation, fundus color photography, and wide-field fluorescein fundus angiography (FFA). Peripheral blood of all the subjects was collected, the pathogenic genes were screened by whole exome sequencing, and NDP genes were detected by amplification of multiple ligated probes. DNA prenatal diagnosis was performed by amniocentesis at 19th weeks of the mother's third gestation. Results:Proband (Ⅲ1), male, 4 years old, full term natural delivery. At about 40 days after birth, B-mode ultrasonography indicated total retinal detachment in both eyes. Normal hearing and intelligence. Fundus examination was not performed. First sibling of proband (Ⅲ2, big younger brother), ophthalmologic examination 30 days after birth, retinal detachment in both eyes. Proband's mother (Ⅱ2) had unvascularized peripheral temporal retina in both eyes. Wide-angle FFA examination showed no vascularization of the peripheral temporal retina in both eyes, and slight leakage of peripheral vascular fluorescein. The proband's second sibling (Ⅲ3, little younger brother) was screened for neonatal eye disease 1 day after birth. No abnormalities were observed outside both eyes. Cornea and lens transparent. No abnormalities were observed in the optic disc and macula in both eyes. No vascular curvature was observed in the peripheral retina. The results of gene detection showed that there was hemizygote deletion in exon 2 of NDP gene of the proband (Ⅲ1) and its big younger brother (Ⅲ2). His mother (Ⅱ2) had heterozygosity deletion in exon 2 of NDP gene. The phenotype and genetic test results of the proband's father (Ⅱ1), uncle (Ⅱ3), maternal grandfather (Ⅰ1) and maternal grandmother (Ⅰ2) were not abnormal. Conclusions:The hemizygote deletion in exon 2 of NDP gene is a pathogenic variation in the native family. The clinical phenotypes of different genders are different. Prenatal diagnosis is an effective way to block hereditary diseases in families.