OBJECTIVE: To explore the genetic basis for a Chinese pedigree affected with Branchio-Oto syndrome (BOS). METHODS: A pedigree with BOS which had presented at the Genetics and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University in May 2021 was selected as the study subject. Clinical data of the pedigree was collected. Peripheral blood samples of the proband and her parents were collected. Whole exome sequencing (WES) was carried out for the proband. Multiplex ligation-dependent probe amplification (MLPA) was used to verify the result of WES, short tandem repeat (STR) analysis was used to verify the relationship between the proband and her parents, and the pathogenicity of the candidate variant was analyzed. RESULTS: The proband, a 6-year-old girl, had manifested severe congenital deafness, along with inner ear malformation and bilateral branchial fistulae. WES revealed that she has harbored a heterozygous deletion of 2 466 kb at chromosome 8q13.3, which encompassed the EYA1 gene. MLPA confirmed that all of the 18 exons of the EYA1 gene were lost, and neither of her parents has carried the same deletion variant. STR analysis supported that both of her parents are biological parents. Based on the guidelines from the American College of Medical Genetics and Genomics, the deletion was classified as pathogenic (PVS1+PS2+PM2_Supporting+PP4). CONCLUSION The heterozygous deletion of EYA1 gene probably underlay the pathogenicity of BOS in the proband, which has provided a basis for the clinical diagnosis.
Humans ; Female ; Pregnancy ; Child ; Pedigree ; Family ; Parents ; Chromosomes, Human, Pair 3 ; Exons ; Nuclear Proteins/genetics* ; Protein Tyrosine Phosphatases ; Intracellular Signaling Peptides and Proteins/genetics*

OBJECTIVE: To investigate the genetic characteristics and cause of death for an infant with alveolar capillary dysplasia and pulmonary vein misalignment (ACD/MPV). METHODS: An infant with ACD/MPV diagnosed at the Affiliated Maternity and Child Health Care Hospital of Nantong University in September 2022 was selected as the study subject. Clinical data of the infant were collected. Whole exome sequencing (WES) was carried out to detect genetic variants in the skin tissue, and Sanger sequencing was performed for verifying the candidate variants in the parents. Droplet digital PCR (ddPCR) was used to determine the mosaicism ratio of the variant in different germ layer-derived samples from the father. RESULTS: The infant had died within 2 days after birth due to hypoxemia and respiratory distress. WES revealed that she has harbored a c.433C>T nonsense variant in exon 1 of the FOXF1 gene, which was unreported previously. Sanger sequencing has verified the variant in the infant, with her mother's locus being the wild-type and a minor variant peak noted in her father. ddPCR indicated that the mosaic ratio of the c.433C>T variant in the father's sperm was 27.18%, with the mosaic ratios of the variant in tissues originating from the three germ layers ranging from 11% to 28%. CONCLUSION The c.433C>T variant derived from the paternal germline and somatic mosaicism of the FOXF1 gene had probably predisposed to the neonatal death of this infant. ddPCR is an effective method for detecting mosaic variants.
Female ; Humans ; Pregnancy ; Child ; Infant ; Infant, Newborn ; Male ; Semen ; Infant Death ; Exons ; Mosaicism ; Forkhead Transcription Factors/genetics*

OBJECTIVE: To explore the laboratory phenotype and molecular pathogenesis in a Chinese pedigree affected with Hereditary coagulation factor Ⅻ (FⅫ) deficiency. METHODS: A male proband admitted to Ningbo No.2 Hospital on July 17, 2021 due to chronic gastritis and members of his pedigree (7 individuals from three generations) were selected as the study subjects. Prothrombin time (PT), activated partial thromboplastin time (APTT), FⅧ activity (FⅧ: C), FⅨ activity (FⅨ: C), FⅪ activity (FⅪ: C), FⅫ activity (FⅫ: C), and FⅫ antigen (FⅫ: Ag) were determined. All of the exons, exon-intronic boundaries, as well as the 5'- and 3'-untranslated regions of the F12 gene were subjected to Sanger sequencing. Candidate variants were verified by cloning sequencing. The effect of candidate variants on the protein function was analyzed by bioinformatics software. RESULTS: The proband, a 47-year-old male, had significantly prolonged APTT (180.0 s) and decreased FⅫ:C and FⅫ:Ag levels (< 1%). His father, mother, brother and two sons also showed certain degrees of reduction. Genetic testing revealed that the proband has harbored compound heterozygous variants of the F12 gene, namely c.1092_1093insC (p.Lys365Glnfs*69) in exon 10 and c.1792_1796delGTCTA (p.Val579Hisfs*32) in exon 14. His mother and elder son were heterozygous for the c.1092_1093ins variant, whilst his father, brother, and younger son were heterozygous for the c.1792_1796delGTCTA variant. Analysis of the promoter region of exon 1 also showed that the proband and both sons had harbored a 46T/T polymorphism, whilst other family members were 46C/T. Bioinformatic analysis suggested that the p.Val579 is a highly conserved site. Protein model analysis showed that, with the p.Val579Hisfs*32 variant, a benzene ring was added and the hydrogen bond of surrounding amino acids was changed. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.1792_1796delGTCTA was classified as a pathogenic variant (PVS1+PM2_Supporting+PM4). CONCLUSION The c.1092_1093insC (p.Lys365Glnfs*69) and c.1792_1796delGTCTA (p.Val579Hisfs*32) compound heterozygous variants of the F12 gene probably underlay the decreased FXII levels in this pedigree. Above finding has also enriched the mutational spectrum for FⅫ deficiency.
Male ; Humans ; Aged ; Middle Aged ; Pedigree ; East Asian People ; Exons ; Introns ; Family ; Factor XII Deficiency/genetics* ; 3' Untranslated Regions ; Factor XII/genetics*

OBJECTIVE: To explore the genetic basis for a patient with Alport syndrome (AS) and confirm the existence of a splicing variant. METHODS: An AS patient diagnosed at the Affiliated Hospital of Inner Mongolia Medical University on January 8, 2021 for significant proteinuria and occult hematuria was selected as the study subject. Clinical data was collected. Peripheral blood samples were collected for the extraction of genomic DNA. Whole exome sequencing and Sanger sequencing were carried out to identify potential genetic variants. An in vitro experiment was also conducted to verify the abnormal mRNA splicing. Bioinformatic software was used to analyze the conservation of amino acids of the variant sites and simulate the 3D structure of the variant collagen IV protein. Immunofluorescence and immunohistochemistry were carried out on renal tissues from the patient to confirm the presence of AS kidney injury. RESULTS: The patient, a 21-year-old male, had a 24-hour urine protein of 3.53 g/24 h, which fulfilled the diagnostic criteria for proteinuria. His blood uric acid has also increased to 491 μmol/L. DNA sequencing revealed that he has harbored a c.835-9T>A splice variant of the COL4A5 gene, which was not found in either of his parents. In vitro experiment confirmed that the variant has removed 57 bp from the exon 15 of the mRNA of the COL4A5 gene. The deletion may cause loss of amino acid residues from positions 279 to 297, which in turn may affect the stability of the secondary structure of the α5 chain encoded by the COL4A5 gene. The amino acids are conserved across various species. The result of homology modeling indicated that the trimerization of Col-IV with the mutated α5 chain could be achieved, however, the 3D structure was severely distorted. The AS kidney damage was confirmed through immunofluorescence assays. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.835-9T>A variant was classified as likely pathogenic (PVS1_Moderate+PS3_Moderate+PM2_Supporting+PS2+PP3+PP4). CONCLUSION The c.835-9T>A variant of the COL4A5 gene probably underlay the AS in this patient. In vitro experiment has confirmed the abnormal splicing caused by the variant. Histopathological examination of the kidney tissue has provided in vivo evidence for its pathogenicity. Above finding has expanded the mutational spectrum of the COL4A5 gene.
Humans ; Male ; Young Adult ; Amino Acids ; China ; Collagen Type IV/genetics* ; Exons ; Nephritis, Hereditary/genetics* ; RNA Splicing

OBJECTIVE: To explore the genetic basis of a child with Very early onset inflammatory bowel disease (VEOIBD). METHODS: A female child who had presented at the Children's Hospital of Fudan University on May 23, 2018 due to occurrence of diarrhea and fever 6 days after birth was selected as the study subject. Clinical data of the child was collected. Family-based whole-exome sequencing (WES) was carried out. Candidate variant was verified by Sanger sequencing and PCR of the patient and her parents. RESULTS: The child had developed the symptoms 6 days after birth, with main manifestations including diarrhea, fever, failure to thrive, rectovestibular fistula and hypothyroidism. An enterostomy was performed at the age of 3.5 months due to severe intestinal adhesion and obstruction. Based on her clinical manifestations, colonoscopic finding, and results of biopsies, she was diagnosed with VEOIBD in conjunct with congenital hypothyroidism. Replacement treatment of levothyroxine was given since one month of age. Family-based WES revealed that the child has harbored compound heterozygous variants of the DUOX2 gene, namely c.2654G>T (p.R885L) and c.505C>T (p.R169W), in addition with a heterozygous c.301C>T (p.R101W) variant of the IL10RA gene. Re-analysis of the WES data revealed that the patient also had a 333 bp deletion spanning exon 1 of the IL10RA gene (Chr11: 117857034_117857366). CONCLUSION For patients with VEOIBD, genetic testing is recommended. Presence of additional DUOX2 gene variants might have exacerbated the clinical symptoms in this patient. Above finding has facilitated genetic counseling and prenatal diagnosis for this family, and raised clinicians' awareness of this rare disease.
Female ; Humans ; Infant ; Pregnancy ; Diarrhea ; Dual Oxidases/genetics* ; Exons ; Failure to Thrive ; Inflammatory Bowel Diseases/genetics*

Objective: To analyze the clinical and molecular diagnostic status of Fanconi anemia (FA) in China. Methods: The General situation, clinical manifestations and chromosome breakage test and genetic test results of 107 pediatric FA cases registered in the Chinese Blood and Marrow Transplantation Registry Group (CBMTRG) and the Chinese Children Blood and Marrow Transplantation Registry Group (CCBMTRG) from August 2009 to January 2022 were analyzed retrospectively. Children with FANCA gene variants were divided into mild and severe groups based on the type of variant, and Wilcoxon-test was used to compare the phenotypic differences between groups. Results: Of the 176 registered FA patients, 69 (39.2%) cases were excluded due to lack of definitive genetic diagnosis results, and the remaining 107 children from 15 hospitals were included in the study, including 70 males and 37 females. The age at transplantation treatment were 6 (4, 9) years. The enrolled children were involved in 10 pathogenic genes, including 89 cases of FANCA gene, 7 cases of FANCG gene, 3 cases of FANCB gene, 2 cases of FANCE gene and 1 case each of FANCC, FANCD1, FANCD2, FANCF, FANCJ, and FANCN gene. Compound heterozygous or homozygous of loss-of-function variants account for 69.2% (72/104). Loss-of-function variants account for 79.2% (141/178) in FANCA gene variants, and 20.8% (37/178) were large exon deletions. Fifty-five children (51.4%) had chromosome breakage test records, with a positive rate of 81.8% (45/55). There were 172 congenital malformations in 80 children.Café-au-Lait spots (16.3%, 28/172), thumb deformities (16.3%,28/172), polydactyly (13.9%, 24/172), and short stature (12.2%, 21/172) were the most common congenital malformations in Chinese children with FA. No significant difference was found in the number of congenital malformations between children with severe (50 cases) and mild FANCA variants (26 cases) (Z=-1.33, P=0.185). Conclusions: FANCA gene is the main pathogenic gene in children with FA, where the detection of its exon deletion should be strengthened clinically. There were no phenotypic differences among children with different types of FANCA variants. Chromosome break test is helpful to determine the pathogenicity of variants, but its accuracy needs to be improved.
Male ; Female ; Humans ; Child ; Fanconi Anemia/genetics* ; Chromosome Breakage ; Retrospective Studies ; Exons ; China/epidemiology*

OBJECTIVE: To explore the molecular mechanism for an individual with Bweak subtype. METHODS: Serological methods were used to identify the proband's phenotype. In vitro enzyme activity test was used to determine the activity of B-glycosyltransferase (GTB) in her serum. The genotype was determined by PCR amplification and direct sequencing of exons 5 to 7 and flanking sequences of the ABO gene. T-A cloning technology was used to isolate the haploids. The primary physical and chemical properties and secondary structure of the protein were analyzed with the ProtParam and PSIPRED software. Three software, including PolyPhen-2, SIFT, and PROVEAN, was used to analyze the effect of missense variant on the protein. RESULTS: Serological results showed that the proband's phenotype was Bweak subtype with anti-B antibodies presented in her serum. In vitro enzyme activity assay showed that the GTB activity of the subject was significantly reduced. Analysis of the haploid sequence revealed a c.398T>C missense variant on the B allele, which resulted in a novel B allele. The 398T>C variant has caused a p.Phe133S substitution at position 133 of the GTB protein. Based on bioinformatic analysis, the amino acid substitution had no obvious effect on the primary and secondary structure of the protein, but the thermodynamic energy of the variant protein has increased to 6.07 kcal/mol, which can severely reduce the protein stability. Meanwhile, bioinformatic analysis also predicted that the missense variant was harmful to the protein function. CONCLUSION The weak expression of the Bweak subtype may be attributed to the novel allele of ABO*B.01-398C. Bioinformatic analysis is helpful for predicting the changes in protein structure and function.
Female ; Animals ; ABO Blood-Group System/genetics* ; Phenotype ; Genotype ; Exons ; Alleles

OBJECTIVE: To explore the genetic basis for three Chinese patients with McCune-Albright syndrome (MAS). METHODS: Three children who had respectively presented at Shandong Provincial Hospital in April 2019 and Peking Union Medical College Hospital in August 2020 and May 2021 were selected as the research subjects. Peripheral blood samples of the probands and their family members were taken for the extraction of genomic DNA. Potential variants were screened by whole exome sequencing (WES), and candidate variants were validated by Sanger sequencing of the patients and their family members. RESULTS: The proband from family 1 was found to harbor a heterozygous c.601C>T (p.R201C) missense variant in exon 8 of the GNAS gene, whilst the probands from families 2 and 3 were both found to harbor a heterozygous c.602G>A (p.R201H) missense variant in exon 8 of the GNAS gene. Both variants were known to be pathogenic, and all probands were found to be mosaics for the corresponding variants but with various degrees. CONSLUSION WES can effectively diagnose MAS and other somatic genetic disorders. In this study, the combined WES and Sanger sequencing have verified the degree of mosaicisms of pathogenic variants in the three MAS patients, albeit no apparent correlation was found between the degree of mosaicisms and the phenotype of patients. Above finding has provided a basis for genetic counseling and prenatal diagnosis for the affected families.
Humans ; Mutation ; Fibrous Dysplasia, Polyostotic/genetics* ; East Asian People ; Exons ; Phenotype ; Pedigree

OBJECTIVE: To retrospectively analyze the clinical phenotypes and genetic variants in two Chinese pedigrees affected with Hereditary hypofibrinemia (IFD) and explore their molecular pathogenesis. METHODS: Two probands and their pedigree members were admitted to the First Affiliated Hospital of Wenzhou Medical University on March 30, 2021 and May 27, 2021, respectively. Clinical phenotypes of the probands were collected, and blood clotting indexes of the probands and their pedigree members were determined. Variants of the FGA, FGB and FGG genes were analyzed by Sanger sequencing, and candidate variants were verified by sequence comparison. Bioinformatic software was used to analyze the conservation of the amino acids and pathogenicity of the proteins. Alteration in protein structure and intermolecular force before and after the variant was analyzed by simulating the protein model. RESULTS: Proband 1, a 18-year-old male, had significantly low plasma fibrinogen activity (Fg:C) and plasma fibrinogen antigen (Fg:Ag), respectively at 0.80 g/L and 1.00 g/L. Proband 2, a 43-year-old male, had slightly low Fg:C and Fg:Ag at 1.35 g/L and 1.30 g/L, respectively. The Fg:C and Fg:Ag of proband 1's father, proband 2's father and son were also below the normal level. Genetic testing showed that proband 1 had harbored a heterozygous missense variant of c.688T>G (p.Phe230Val) in exon 7 of the FGG gene, which was inherited from his father. Proband 2, his father and son all had harbored a heterozygous variant of c.2516A>C (p.Asn839Thr) in exon 6 of the FGA gene. Homology analysis showed that the Phe230 and Asn839 residues were highly conserved among homologous species. Bioinformatic analysis predicted that both p.Phe230Val and p.Asn839Thr were pathogenic variants. CONCLUSION Analysis of protein simulation model showed that the p.Asn839Thr variant has changed the hydrogen bo`nd between the amino acids, thus affecting the stability of the protein structure. The heterozygous missense variants of p.Phe230Val and p.Asn839Thr probably underlay the IFD in the two pedigrees.
Humans ; Male ; Amino Acids ; East Asian People ; Exons ; Pedigree ; Retrospective Studies ; Afibrinogenemia/genetics* ; Mutation, Missense ; Fibrinogen/genetics*

OBJECTIVE: To analyze the clinical manifestation and genetic basis for four children with delayed onset Ornithine transcarbamylase deficiency (OTCD). METHODS: Clinical data of four children with OTCD admitted to the Children's Hospital of the First Affiliated Hospital of Zhengzhou University from January 2020 to April 2021 were reviewed. Peripheral blood samples of the children and their parents were collected and subjected to whole exome sequencing (WES). Bioinformatic analysis and Sanger sequencing verification were carried out to verify the candidate variants. Impact of the candidate variants on the protein structure was also predicted. RESULTS: The clinical manifestations of the four children included vomiting, convulsion and disturbance of consciousness. WES revealed that the child 1 was heterozygous for a c.421C>T (p.R141X) variant in exon 5, children 2 and 3 were hemizygous for a c.119G>A (p.R40H) variant in exon 2, and child 4 was hemizygous for a c.607T>A (p.S203T) variant in exon 5 of the OTC gene. Among these, the c.607T>A variant was unreported previously and predicted to be pathogenic (PM1+PM2_Supporting+PP3+PP4). Bioinformatic analysis has predicted that the variant may result in breakage of hydrogen bonds and alter the protein structure and function. Sanger sequencing confirmed that the variants in children 2 to 4 have derived from their mothers. CONCLUSION The pathogenic variants of the OTC gene probably underlay the delayed OTCD in 4 children. The discovery of the c.607T>A variant has enriched the mutational spectrum of the OTC gene.
Child ; Humans ; Ornithine Carbamoyltransferase Deficiency Disease/genetics* ; Exons ; Seizures ; Computational Biology ; Heterozygote