Objective: To investigate the clinical phenotype and genetic diagnosis process of fetuses with 21 hydroxylase deficiency (21-OHD) caused by compound heterozygous variant of the CYP21A2 gene .
Methods: A fetus who was diagnosed at Taizhou Hospital in Zhejiang Province on December 4, 2020 due to unclear characteristics of external genitalia on ultrasound was selected as the study subject. Chromosome copy number variation sequencing (CNV-seq) and whole exome sequencing (WES) were performed on amniotic fluid samples. Candidate variants were validated by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA), and short tandem repeat (STR) analysis was used to exclude maternal blood contamination. The pathogenic mechanism of the variants was further explored. The procedure followed by this study was approved by the Medical Ethics Committee of Taizhou Hospital (Ethics No.: K20201009).
Results: The MRI examination of the fetal external genitalia showed thickening of labia minora and enlargement of the clitoris. The CNV-seq results of the fetus showed no significant abnormality. The WES results showed that the fetus had a homozygous c.293-13C>G variant in the CYP21A2 gene (NM-000500.9). STR testing excluded maternal blood contamination. Sanger sequencing verified the presence of heterozygous c.293-13C>G variant of the CYP21A2 gene in the fetus and its mother, while its father did not detect this mutation. Further MLPA testing results showed that the fetus and its father had heterozygous deletion (I2G-C locus) mutations in exon 1~7 of the CYP21A2 gene. Based on the "Standards and Guidelines for Interpretation of Sequence Variants" jointly developed by the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP), both variants of the CYP21A2 gene carried by the fetus were predicted to be pathogenic. According to the imaging and genetic testing results of the external genitalia of the fetus, the fetus was prenatally diagnosed as 21-OHD caused by the CYP21A2 gene variant. Follow-up after prenatal diagnosis showed that the couple had opted to terminate the pregnancy at a local hospital at 31+ weeks of gestation, and the clinical phenotype of the abortion fetus was consistent with the imaging and molecular genetic diagnosis.
Conclusion: The imaging features of this fetus are suspected to be congenital adrenal hyperplasia (CAH). Combined with WES, Sanger sequencing, and MLPA testing results, the fetus was diagnosed with 21-OHD caused by compound heterozygous variants of the CYP21A2 gene, which provided a basis for prenatal diagnosis.
Objective: To investigate the clinical characteristics and genetic etiology of eight members from a pedigree affected with epidermolysis bullosa (EB).
Methods: A girl presented with recurrent, unexplained blisters on the palmar and plantar skin for 8 years and sought medical care in October 2024 was enrolled as the study subject. A retrospective study was conducted to collect the child's clinical data, and a detailed medical history was taken for her family members. Peripheral venous blood samples were collected from the child and her parents for genomic DNA extraction. Whole-exome sequencing (WES) was performed. Candidate variant was validated by Sanger sequencing. The pathogenicity of the candidate variants was classified in accordance with the Standards and Guidelines for the Interpretation of Sequence Variants issued by the American College of Medical Genetics and Genomics (ACMG, hereinafter referred to as the "ACMG Guidelines"). This study was approved by the Medical Ethics Committee of the 980th Hospital of the Joint Logistics Support Force of the Chinese People's Liberation Army (Ethics No.: 2019-KY-01).
Results: The proband was an 8-year-and-4-month-old female. Four months after birth, she had developed recurrent blisters on the palmar and plantar skin without obvious triggers, accompanied by significant pain. Symptoms were more severe in summer and slightly relieved in winter. Although symptomatic treatment could alleviate the symptoms, she was unable to participate in physical activities. A detailed family history revealed that her great-grandfather, grandfather, father, half-brother, great-aunt, great-aunt's son and two grandsons, as well as her aunt and aunt's son, had similar clinical manifestations. WES revealed that she has harbored a heterozygous c.556-16(IVS1)C>G (NM_000424.4) variant in the KRT5 gene, which was identified as a splice site mutation. Reverse transcription sequencing confirmed that this variant can disrupt normal splicing, resulting in retention of a 15 bp sequence in the first intron. Sanger sequencing demonstrated that the variant was inherited from the father, and the 6 aforementioned relatives with similar phenotypes have all carried the same variant (the great-grandfather, grandfather, and great-aunt had declined genetic testing due to advanced age). Based on the ACMG guidelines, this variant was classified as pathogenic (PS3+PM2_Supporting+PP3+PP1_strong).
Conclusion: Patients with epidermolysis bullosa simplex may exhibit clinical features including blistering on the skin or mucous membranes of friction-prone sites (e.g. hands, feet, elbows, and knees) following minor trauma or friction, as well as increased skin fragility. The c.556-16(IVS1)C>G (rs376462752) variant of the KRT5 gene probably underlay the pathogenesis of EB in this child. Above findings have enriched the mutational spectrum of the KRT5 gene.
Objective: To assess the clinical value of non-invasive prenatal testing (NIPT) for identifying maternal malignant tumors.
Methods: A retrospective analysis was carried out on pregnant women undergoing Non-invasive prenatal testing (NIPT) at Taizhou Hospital in Zhejiang Province from January 2018 to December 2022. The criteria included maternal copy number variations for at least two chromosomes. Clinical follow-up data were obtained for the high-risk population of maternal malignant tumors through telephone follow-up and review of electronic medical records. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: K20250339).
Results: Among 45 141 NIPT samples, 6 (0.013%) were suggested to have maternal malignant tumors. Follow-up information was available for 5 patients (83.3%). Two cases were diagnosed with maternal malignant tumors, including 1 myelodysplastic syndrome and 1 pelvic malignant tumor. Two cases were found to have multiple uterine fibroids and 1 was lost during follow-up.
Conclusion: The abnormal copy number indicated by NIPT may serve as an early signal for maternal malignant tumors. To establish a systematic follow-up protocol and multidisciplinary collaboration are conducive to achieving early diagnosis of tumors and improving the prognosis of patients. Based on the results of this study, it is recommended that for pregnant women with unexplained copy number variations and suspected maternal tumors by NIPT, targeted tumor screening program should be implemented to optimize their clinical management.
Objective: To explore the mechanism and clinical manifestations of a case with complex structural variations involving chromosomes 5, 7, and 14, and assess the value of Chromosome conformation-based karyotyping (C-MoKa) for its diagnosis.
Methods: Two half-sibs by the same father presented at the First Hospital of Lanzhou University in December 2024 for severe multi-system abnormalities were selected as study subjects. Peripheral blood samples from the their parents were subjected to conventional chromosomal karyotyping analysis. The father was further analyzed using C-MoKa, while both siblings underwent copy number variation sequencing (CNV-seq). This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: LDYYSZLLKH2025-05).
Results: Conventional karyotype analysis indicated that the father has a karyotype of 46,XY,add(5)(p15.3). CNV-seq identified multiple chromosomal abnormalities in both siblings, including duplications and deletions of chromosomes 14 and 5. C-MoKa analysis further revealed a complex chromosomal structural variation involving chromosomes 5, 7, and 14 in the father. These variations were closely associated with the severe phenotypes noted in both children.
Conclusion: Complex chromosomal structural variations can lead to multi-system abnormalities and significantly impact reproductive health. Compared to conventional karyotyping, the C-MoKa technique has shown significant advantage in identifying such complex rearrangements. The combined application of multiple techniques can improve the accuracy of diagnosis, enabling genetic counseling for carriers to reduce their risk for producing further affected offspring.
Objective: To analyze the clinical phenotype and genetic basis of four children with CHARGE syndrome.
Methods: A retrospective analysis was conducted on four children diagnosed with CHARGE syndrome at Xiamen Children's Hospital from May 2019 to May 2025. Peripheral venous blood samples were collected from the children and their parents and subjected to trio-whole exome sequencing. Candidate variants were verified by Sanger sequencing. Online tools were used for the conservation analysis and protein structure prediction. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2024-126).
Results: The four children have included two neonates, one infant and one child, with their age at the initial diagnosis ranging from 16 days after birth to 11 years old. Their initial manifestations were not typical of CHARGE syndrome. All children were found to harbor missense variants of the CHD7 gene, including c.3059T>C (p.L1020S), c.3302G>A (p.C1101Y), c.5879C>T (p.S1960F) and c.8093C>T (p.S2698L). Sanger sequencing confirmed that two were de novo variants, and two were inherited from their parents. In child 1, the leucine at position 1020 was highly conserved, and the p.L1020S variant did not alter the spatial structure and hydrogen bond connections of the CHD7 protein, though the shape of the binding cavity and the number and distribution of binding probe clusters have changed. In child 4, an unreported variant in the epilepsy gene SCN9A (c.2152T>C, p.Y718H) was detected, along with bilateral lower limb deformities. Literature review suggested that missense variants of the CHD7 gene were most common (32.1%) among the Chinese population, whilst nonsense variants had the highest lethality rate (41.2%) in neonates.
Conclusion: Variants of the CHD7 gene probably underlay the pathogenesis in the four children. Changes in the binding sites and binding cavity morphology play an important role in CHARGE syndrome. The types of genetic variants in CHARGE patients may vary between different regions and races.
Objective: To explore the clinical and genetic characteristics of a patient with Beck-Fahrner syndrome attributed to a TET3 gene variants.
Methods: A case of Beck-Fahrner syndrome (proband) who was treated at the Children's Hospital of Nanjing Medical University in December 2021 was selected as the study subject. Clinical data of the family were collected. Peripheral blood samples of the proband and his parents were collected, and genomic DNA was extracted for whole exome sequencing (WES). Candidate variants were verified in the family by Sanger sequencing. According to the "Classification Criteria and Guidelines for Genetic Variations" formulated by the American College of Medical Genetics and Genomics (hereinafter referred to as "ACMG guidelines"), the pathogenicity of the TET3 gene variant sites was rated. This study was approved by the Medical Ethics Committee of the Children's Hospital of Nanjing Medical University (Ethics No.: 202402022-1).
Results: The proband was a male, with a age of 9 months at the time of consultation. His clinical manifestations included decreased muscle tone, global developmental delay, long face, and open mouth. WES revealed that he has harbored a c.2811_c.2812insAGAC (p.T938fs*27) (NM_001287491) truncation variant in exon 7 of the TET3 gene. Sanger sequencing showed that neither of his parents has harbored the same variant. According to the ACMG guidelines, the variant was rated as pathogenic (PVS1+PS2+PM2_Supporting).
Conclusion: The TET3 gene c.2811_c.2812insAGAC variant probably underlay the pathogenesis of Beck-Fahrner syndrome in the proband. Above discovery has enriched the mutational spectrum of the TET3 gene and provided a reference for the diagnosis and treatment of this disease.
Objective: To investigate the clinical phenotype and genetic characteristics of an infertile woman carrying a novel PADI6 gene variant.
Methods: An infertile woman who visited the Medical Genetics Center of Henan Provincial People's Hospital on April 29, 2024 was selected as the study subject. Clinical data of the proband and her family members were collected. Peripheral blood samples were obtained from the proband and her husband for genomic DNA extraction. Whole-exome sequencing (WES) was performed. Candidate variant was verified among the family members by Sanger sequencing. The pathogenicity of candidate variant was classified according to the American College of Medical Genetics and Genomics (ACMG) Standards and Guidelines for the Interpretation of Sequence Variants. Relevant literature on the pathogenic variants of the PADI6 gene was reviewed for genotype-phenotype correlation analysis. This study was approved by the Medical Ethics Committee of Henan Provincial People's Hospital (Ethics No.: 2021-171).
Results: The proband was a 35-year-old woman who underwent two oocyte retrieval cycles, yielding a total of five oocytes, with all embryos arrested at day 3 post-fertilization. WES identified a homozygous PADI6 variant, c.367+4_367+7del. In vitro splicing assay confirmed that this variant can cause skipping of exon 3, leading to a frameshift and alterations in the protein structure or premature termination of translation. Literature review identified 12 relevant publications, and the PADI6 c.367+4_367+7del was determined to be a novel variant.
Conclusion: The homozygous PADI6 c.367+4_367+7del variant probably underlay the pathogenesis of infertility in the proband.
Objective: To explore the clinical features and genetic etiology of a child with Hoyeraal-Hreidarsson syndrome (HHS).
Methods: A child with HHS diagnosed at the Affiliated Hospital of Jining Medical University due to "developmental delay and anaemia" on April 27, 2024 was selected as the study subject. Clinical data of the child was collected. Genomic DNA was extracted from peripheral blood samples of the child and his family members. Whole-exome sequencing was carried out, and candidate variant was verified by Sanger sequencing of his family members and bioinformatics analysis using CASAVA v1.8.2. The pathogenicity of the candidate variant was rated according to the Standards and Guidelines for the Interpretation of Sequence Variants released by the American College of Medical Genetics and Genomics (ACMG). Relevant literature on HHS cases reported in China was reviewed to analyze the clinical and genetic characteristics. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2024-10-C003).
Results: The child, a 7-month-old boy, had mainly manifested with growth retardation, developmental delay, microcephaly, cerebellar hypoplasia, immunodeficiency and bone marrow failure. Routine blood test indicated pancytopenia. The immunological workup showed reduction of B cells, NK cells and immunoglobulins. Cranial MRI demonstrated the volume of bilateral cerebellar hemispheres and brainstem and corpus callosum was small. Whole-exome sequencing revealed that he has harbored a hemizygous c.103_105del (p.Glu35del) variant of the DKC1 gene. Sanger sequencing showed that his mother and two sisters have carried the same variant. Based on the ACMG guidelines, the variant was predicted to be likely pathogenic (PM1+PM4+PS4_Supporting+PM2_Supporting). Four relevant literature were retrieved, which has involved 8 HHS cases. Together with the patient from this study, they have consisted of 8 males and 1 females. The most common symptoms of the 9 patients were blood system abnormalities and developmental delay. All patients had shown cerebellar dysplasia and anemia/erythrocytopenia. Among them, 3 cases have harbored TINF2 gene variants, and 6 cases had harbored DKC1 gene variants. The c.103_105del variant has not been reported in China previously.
Conclusion: The hemizygous c.103_105del (p.Glu35del) variant of the DKC1 gene probably underlay the disease in this child. Above finding has expanded the mutational and phenotypic spectra of the DKC1 gene, and has facilitated early diagnosis of HHS in this child.
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