Objective:To explore the clinical phenotype and genetic variant in a Chinese pedigree affected with Hunter syndrome and create immortalized cell lines for the affected pedigree members.Methods:A pedigree of six members who had visited Xi′an Children′s Hospital in July 2022 was selected as the study subject. Clinical data was collected. Whole exome sequencing was carried out for the pedigree members. Candidate variant was verified by Sanger sequencing. In addition, peripheral B lymphocytes were transfected with Epstein-Barr virus to create immortalized cell lines, which were then subjected to enzyme activity analysis.Results:The patient, a five-year-and-seven-month-old boy, had exhibited stiff limbs and enlarged joints. He had developed hernia, scaphocephaly, and barrel chest from 3 months of age. His uncle also had stiff limbs, poor hearing, blindness, and right oblique inguinal hernia. Above features had resembled those of Hunter syndrome. Genetic testing revealed that both the child and his uncle had harbored an IDS (NM_000202.8): c. 823G>A (p.D275N) variant, which was unreported previously. Bioinformatic analysis indicated that the D275 to be a highly conserved site, and the D275N variant may affect the stability of the protein′s spatial conformation, thereby decrease the catalytic activity of the enzyme. The successfully constructed immortalized lymphoblastoid cell lines for the child and his parents showed increased volume, irregular shape, burr structure and cluster growth. And the value of IDS activity of the patient′s immortalized lymphoblastoid cells was below the limit of detection. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as likely pathogenic (PS3+ PM2_Supporting+ PM5+ PP1+ PP3). Conclusion:Above finding has enriched the phenotypic and mutational spectra of Hunter syndrome, and provided a basis for the genetic counseling for this pedigree. The creation of immortalized cell lines has offered a model for further investigation of the impact of variant on the function of IDS and development of targeted drugs.

Objective:To analyze the clinical characteristics of a child with Congenital disorder of glycosylation due to compound heterozygous variants of COG6 gene ( COG6-CDG). Methods:A child who was admitted to Xi′an Children′s Hospital on January 10, 2023 was selected as the study subject. Clinical data were collected. Pathogenic variants were analyzed by whole exome sequencing, and candidate variants were verified by Sanger sequencing, in vitro experiments and bioinformatic analysis. This study was approved by the Medical Ethics Committee of Xi′an Children′s Hospital (No. 20230101). Results:The child, a 1-month-8-day-old male, was admitted for diarrhea and weight loss for one month. He had presented with cholestasis, diarrhea, facial dysmorphism, poor response, bilateral Simian crease, and brain atrophy. After discharge, he had continued to have high fever, feeding difficulty, and deceased finally. Whole exome sequencing results showed that he had harbored compound heterozygous variants of the COG6 gene, namely c. 807delT (p.F269Lfs*37) and c. 1746+ 1G>C (p.Gly565_Met582del). Sanger sequencing verified that the variants were inherited from his father and mother, respectively. In vitro experiments verified that the c. 1746+ 1G>C variant could affect the mRNA splicing and produce a truncated protein, whilst the c. 807delT variant could significantly reduce gene expression at both mRNA and protein levels. Based on the guidelines from the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP), the variants were classified as pathogenic (PVS1+ PM3+ PM2_Supporting) and likely pathogenic (PVS1+ PM2_Supporting), respectively. Conclusion:The c. 807delT (p.F269Lfs*37) and c. 1746+ 1G>C (p.Gly565_Met582del) compound heterozygous variants of the COG6 gene probably underlay the pathogenesis of this child. Above finding has enriched the mutational spectrum of COG6-CDG and provided a basis for the genetic counseling for this family.

Objective:To analyze the gene variants of a patient affected with Duchenne/Becker muscular dystrophy in a pedigree and further explore the genotype-phenotype correlation for providing basis for family genetic counseling.Methods:The clinical features and family history of family members were collected.Multiplex ligation-dependent probe amplification(MLPA)was utilized to detect copy number variation of target genes.The pathogenic variations were ana-lyzed by whole exome sequencing(WES).The suspected gene variations were verified by Sanger sequencing.For the splice site mutations,mini-gene was constructed and expressed in vitro to detect the number of transcript and cDNA se-quence.Results:The proband of this family is a male,with no obvious involvement of the lower limbs.Laboratory tests showed an elevated level of creatine kinase(CK)in peripheral blood(700-1600 U/L),and electromyography showed myogenic damage.MLPA did not detect pathogenic exon copy number variation in dystrophin(DMD)gene.Genetic testing showed the proband carried a maternal hemizygotic splicing variation of DMD gene(NM_004006.2):c.2622+2T＞C.An in vitro mini-gene splicing assay confirmed that this splicing mutation could affect RNA splicing.According to clinical features and genetic testing results,the proband was speculated first proof of Duchenne/Becker muscular dys-trophy(DMD/BMD)caused by DMD gene mutation.Conclusion:This study identified the pathogenic variation of a proband with DMD/BMD of DMD gene,which enriched the variation spectrum of DMD/BMD in China.It was con-firmed that the splicing variation of the DMD gene c.2622+2T＞C can produce multiple transcripts leading to different functional impairments,and based on the specificity of temporal and spatial expression,it corresponded to the mild clin-ical manifestations of the patient,providing some reference value for the correlation between genotype and phenotype.

Objective:To analyze the clinical, genetic, and bioinformatic characteristics of 3 children diagnosed with GM1 gangliosidosis type Ⅰ, and to conduct a literature review.Methods:From January 2020 through December 2022, a detailed examination, encompassing whole-exon sequencing and the evaluation of β-galactosidase enzymatic function, was undertaken for 3 pediatric inpatients at Xi′an Children′s Hospital. Each child presented with distinct clinical features: recurrent seizures, developmental delays, and hypotonia. Concurrently, computational tools MutaBind2 and PyMOL were employed to prognosticate the potential impact of identified genetic mutations.Results:All 3 children experienced severe developmental delay or regression in infancy, accompanied by epilepsy. Serum alkaline phosphatase and aspartate aminotransferase were significantly increased. Furthermore, the serum β-galactosidase activity was 1.59%, 3.47%, 1.96%,respectively. Brain magnetic resonance imaging revealed poor myelination and X-ray examinations demonstrated beak-like changes in the anterior edge of the lumbar spine. All 3 children carried compound heterozygous variants in the GLB1 gene. The c.148T>C variant had not been previously reported, while the c.785G>T, c.1438A>G and c.304C>G variants were only present in 1 case. It was predicted that the mutated protein exhibited reduced binding affinity, with an interrupted hydrogen bond or the formation of a significant steric hindrance with the neighboring residues. Combined with the literature evidence, it was hypothesized that the mutations could potentially impact the overall structure and stability of the GLB protein, leading to a decrease in enzyme activity. Conclusions:The diagnosis and classification of GM1 ganglioside storage disease need to integrate the clinical features, exome sequencing and β-galactosidase activity assay. Bioinformatics analysis is helpful to predict the effect of mutations on protein structure and function.

OBJECTIVE: To analyze the clinical phenotypes and ATP7B gene variants among children patients with Wilson' s disease from Northwestern China. METHODS: The clinical features and variants of the ATP7B gene among 75 children with hepatic Wilson' s disease were retrospectively analyzed. RESULTS: Among the 75 cases, 4 were presymptomatic, 59 had isolated transaminase elevation, 12 had acute and/or chronic liver diseases. Nine children were found to harbor homozygous variants, 64 harbored compound heterozygous variants, and two only had heterozygous variants of the ATP7B gene. In total 49 variants were detected, with common variants including c.2333G>T (p.Arg778Leu), c.2621C>T (p.Ala874Val) and c.2975C>T (Pro992Leu), which yielded allelic frequencies of 28.7%, 12.7% and 9.3%, respectively. Six novel variants were detected, which included c.1908dupC (p.Asn637Glnfs*118), c.4179_4180insC (p.Pro1394Profs*15), c.1604A>G (p.Glu535Gly), c.2278C>T (p.Pro760Ser), c.3008C>A (p.Ala1003Glu) and c.3532A>C (p.Thr1178Pro). Except for c.1604A>G (p.Glu535Gly), the remainder five were all predicted to be likely pathogenic. No significant correlation was found between genotype and phenotype among the patients. CONCLUSION The common mutation types of the ATP7B gene among patients with hepatic Wilson disease in Northwestern China are c.2333G>T (p.Arg778Leu), c.2621C>T (p.Ala874Val) and c.2975C>T (p.Pro992Leu), there is no significant correlation between their genotypes and phenotypes.
Copper-Transporting ATPases/genetics* ; Genotype ; Hepatolenticular Degeneration/genetics* ; Humans ; Mutation ; Phenotype ; Retrospective Studies

OBJECTIVE: To analyze the clinical features and genetic variants in two unrelated patients with psychomotor retardation and facial abnormalities, and to explore their genotype-phenotype correlation. METHODS: Clinical data and family history of the two pedigrees were collected. Whole exome sequencing (WES) and Sanger sequencing were carried out to detect the potential variants. RESULTS: Both patients had presented with mental and language retardation, along with growth delay and facial anomalies. They were both found to harbor de novo loss-of-function variants in exon 12 of the ASXL3 gene, namely c.3096dup (p.Pro1033Thrfs*2) and c.3253G>T (p.Gly1085*). Neither variant was reported previously. Combined with their clinical features and genetic finding, both patients were diagnosed with Bainbridge-Ropes syndrome due to pathogenic variants of the ASXL3 gene. CONCLUSION Diagnosis of Bainbridge Ropes syndrome in the two pedigrees has enriched the genotypic and phenotypic spectrum of this disorder and enabled genetic counseling for them.
Child ; China ; Developmental Disabilities/genetics* ; Humans ; Language ; Mutation ; Pedigree ; Phenotype ; Transcription Factors/genetics*

OBJECTIVE: To explore the genetic basis for two unrelated patients with global developmental delay and coarse facial features. METHODS: Clinical data and family history of the two pedigrees were collected. Whole exome sequencing and Sanger sequencing were carried out to detect potential variants. RESULTS: The two patients have presented with global developmental delay, coarse facies, muscular hypotonia, congenital heart disease, and pectus excavatum, and were found to harbor two de novo loss-of-function variants of the ARID1B gene, namely c.3586delC (p.Gln1196Serfs*15) and c.4954_4957delACGT (p.Thr1652Glyfs*31). Both variants were unreported previously. CONCLUSION The nonsense variants of the ARID1B gene probably underlay the etiology in these patients. Above finding has enriched the genotypic and phenotypic spectrum of the disease and provided a basis for prenatal diagnosis.
Abnormalities, Multiple ; China ; DNA-Binding Proteins/genetics* ; Face/abnormalities* ; Facies ; Hand Deformities, Congenital/genetics* ; Humans ; Intellectual Disability/genetics* ; Micrognathism/genetics* ; Neck/abnormalities* ; Transcription Factors/genetics*

OBJECTIVE: To analyze the clinical characteristics and genetic variant of a child featuring X-linked mental retardation. METHODS: Whole exome sequencing and Sanger sequencing were used for the detection of variant and pedigree validation, respectively. Clinical manifestation of patients with DDX3X gene variants were also reviewed. RESULTS: The child was found to harbor a heterozygous NM_001193416.3: c.1332_1333delCT (p.Leu445Serfs*19) variant of the DDX3X gene. The same variant was not found in either of her parents. CONCLUSION The child was diagnosed with X-linked mental retardation due to variant of the DDX3X gene. Above finding has enriched the spectrum of DDX3X gene variants and provided a basis for clinical diagnosis and prenatal diagnosis for this pedigrees.
Child ; DEAD-box RNA Helicases/genetics* ; Female ; Heterozygote ; Humans ; Intellectual Disability/genetics* ; Mental Retardation, X-Linked/genetics* ; Mutation ; Pedigree ; Pregnancy ; Exome Sequencing

OBJECTIVE: To analyze the clinical features and genetic variants of two patients from a pedigree affected with Smith-Lemli-Opitz syndrome and explore their genotype-phenotype correlation. METHODS: Clinical data and family history of the pedigree were collected. Whole exome sequencing was carried out to identify the potential variants. Suspected variants were verified by Sanger sequencing of the family members. RESULTS: The proband and her sister both presented with feeding difficulty, facial dysmorphism, seizures, and mental and speech retardation. The third child of this family presented with feeding difficulty, poor weight gain and severe malnutrition after birth. He had died of unknown cause at 6 months without genetic testing. The fourth child was a healthy boy. Genetic testing showed that both the proband and her sister have carried c.127G>T (p.Val43Phe) and c.820_825del (p.Asn274_Val275del) compound heterozygous variants of the DHCR7 gene (NM_001360.2), but the fourth child carried neither of the variants. The two variants were unreported in the literature and disease-related databases, and were not included in the 1000G and gnomAD databases. The c.820_825del variant may affect the sterol-sensitive region of the DHCR7 protein, which can lead to deletion of two amino acids at positions 247 and 275, causing truncation of the DHCR7 protein. It is speculated that this may affect the stability of protein's spatial conformation, thereby decrease the activity of the enzyme. The c.127G>T variant may affect the first transmembrane region of the protein, which is involved in the transmembrane transport of proteins. Multiple software predicted it to be harmful. Conservation analysis suggested that the three amino acids all locate in a highly conserved region of the protein. In consideration of the clinical phenotype, family history and result of genetic testing, we speculated that both patients had Smith-Lemli-Opitz syndrome due to variants of the DHCR7 gene. CONCLUSION This pedigree has enriched the phenotypic and genotypic data of Smith-Lemli-Opitz syndrome, which clarified the genetic etiology of the patients and provided a basis for genetic counseling of this pedigree.
China ; Female ; Genetic Testing ; Humans ; Male ; Mutation ; Oxidoreductases Acting on CH-CH Group Donors/genetics* ; Pedigree ; Smith-Lemli-Opitz Syndrome/genetics*

OBJECTIVE: To explore the clinical characteristics and genetic basis of a child with 5α-reductase type 2 deficiency. METHODS: Clinical data of the child was retrospectively analyzed. Targeted capture-next generation sequencing and Sanger sequencing were carried out to detect potential variants. RESULTS: The patient's main features included micropenis and hypospadia. He was found to harbor compound heterozygous c.680G>A (p.R227Q) and c.3G>T (p.M1I) variants of the SRD5A2 gene. Among these, c.680G>A (p.R227Q) was inherited from his father and was a known pathogenic mutation, while c.3G>T (p.M1I) was inherited from his mother and was unreported previously. CONCLUSION The compound heterozygous variants of the SRD5A2 gene probably underlay the disease in this child, who was eventually diagnosed with 5α-reductase 2 deficiency.
3-Oxo-5-alpha-Steroid 4-Dehydrogenase/genetics* ; Child ; Disorder of Sex Development, 46,XY ; Female ; Humans ; Hypospadias ; Male ; Membrane Proteins/genetics* ; Mutation ; Retrospective Studies ; Steroid Metabolism, Inborn Errors ; Steroids