中华医学遗传学杂志最新文献

Objective: To explore the clinical phenotype and genetic characteristics in two children with Knobloch syndrome (KNO) due to variants of COL18A1 gene.

Methods: Two children presented at the Genetic Eye Disease Clinic of the Eye Hospital of Wenzhou Medical University in October 2023 for ocular lesions were selected as the study subjects. Relevant clinical data and peripheral venous blood samples were collected from the children and their parents. Following genomic DNA extraction, whole-exome sequencing (WES) was carried out. Candidate variants were verified by Sanger sequencing of the family members. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 2021-212-K-185).

Results: Both children exhibited characteristic ocular features of KNO including nystagmus, high myopia, and leopard spot fundus. Additionally, child 1 also presented with congenital occipital bone dysplasia and occipital encephalocele, while child 2 was diagnosed with vitreoretinochoroidopathy and bilateral high myopia. WES has identified compound heterozygous variants of the COL18A1 gene in both children, including a c.3013+3A>C splice-site variant and a c.2743C>T (p.Arg915Ter) nonsense variant in child 1, and a novel c.1702-1G>A splice-site variant and a c.3836C>T (p.Ser1279Leu) missense variant in child 2. A comprehensive literature review has identified 63 domestic and international articles involving 167 patients with KNO whom can be classified into three subtypes, with KNO type I being the most common and caused by pathogenic variants in the COL18A1 gene. Both probands in this study were children with KNO type I. Analysis of the genotype-phenotype correlations and population distribution characteristics revealed that the KNO patients exhibited significant clinical and genetic heterogeneity, along with a broad geographic distribution, with a relatively greater number of cases reported in Brazil and China. and a broad geographic distribution, with the highest numbers reported in Brazil and China. While no significant difference in genotype distribution was observed between Chinese and non-Chinese patients, phenotypic disparities were noted, with the non-Chinese cohort showing significantly higher rates of retinal detachment and developmental delay (P < 0.05), whereas Chinese patients exhibited a greater proportion of macular hypoplasia (P < 0.05).

Conclusion: The main clinical manifestations of KNO include high myopia, vitreoretinal dystrophy, and occipital encephalocele. The novel c.1702-1G>A splice-site variant identified in the COL18A1 gene has expanded the mutational spectrum of KNO type I and provided valuable insights for genetic diagnosis, counseling, and clinical management of the disease.

Objective: To analyze the clinical manifestations and genotype of a child with You-Hoover-Fong syndrome (YHFS) to enhance clinical understanding of this disease.

Methods: Clinical data of a child who visited the Department of Pediatric Neurorehabilitation of the Women's and Children's Hospital Affiliated to Xiamen University in March 2025 for global developmental delay was collected. Peripheral blood samples of the child and his parents were collected for chromosomal microarray analysis and whole exome sequencing (WES). Sanger sequencing was performed for parental validation, and candidate variant was assessed for pathogenicity. Clinical and genetic analyses were conducted based on the child's phenotype. A literature review was performed by retrieving previously reported cases of YHFS due to TELO2 gene variants. This study was approved by the Medical Ethics Committee of the Women's and Children's Hospital Affiliated to Xiamen University (Ethics No.: KY-2023-044-K02).

Results: The child was a 1-year-and-2-month-old male presenting with global developmental delay, encephalodysplasia, congenital heart disease and distinctive facial features. WES revealed that the child has harbored compound heterozygous variants of the TELO2 gene, namely c.1826G>A (p.Arg609His) and c.1514_1515delAG (p.Glu505Alafs21). Sanger sequencing confirmed that his mother carried a heterozygous c.1826G>A variant and his father carried a heterozygous c.1514_1515delAG variant. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were classified as likely pathogenic (PM2_Supproting+PM3_Strong+PP1+PP3; PVS1+PM2_Supproting). Literature review has identified 9 articles reporting 31 cases of YHFS due to TELO2 gene variants, with primary clinical manifestations including developmental delay, intellectual disability, distinctive facial features, and congenital heart disease.

Conclusion: The c.1826G>A (p.Arg609His) and c.1514_1515delAG (p.Glu505Alafs*21) compound heterozygous variants of the TELO2 gene probably underlay the pathogenesis of this child. Above finding has provided a basis for the clinical and genetic diagnosis of the child, which also enriched the mutational spectrum of the TELO2 gene, and improved understanding of YHFS.

Objective: To explore the reasons for false negative results by Optical genome mapping (OGM) analysis of three cases and propose strategies for handling them.

Methods: Three patients presented at the Affiliated Hospital of Nantong University between July 2022 and July 2024 were selected as study subjects. The patients included a 37-year-old female with two miscarriages, a 1.5-year-old boy with delayed motor development, and a 35-year-old male whose son had intellectual disability. The patients had undergone comprehensive evaluation with chromosomal karyotyping analysis, single nucleotide polymorphism microarray (SNP array) assay, fluorescence in situ hybridization (FISH), and methylation-specific multiple ligation-dependent probe amplification (MS-MLPA). A retrospective analysis was also carried out on the results of OGM testing. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2020-K004).

Results: The chromosomal karyotype of patient 1 was 46,XX,4qs, and no abnormality was found by SNP array, FISH, and OGM testing. Patient 2 had a normal chromosomal karyotype, and SNP array analysis did not reveal any copy number abnormalities of chromosomal fragments but the presence of a homozygous region of approximately 79.58 Mb at 15q11.2-q26.3 (chr15: 22817871_102397317). MS-MLPA detection indicated that the copy number of the 15q11.2-q13 region was 2, and the degree of methylation was relatively high (average ratio = 1.0). OGM detection confirmed the presence of approximately 67.97 Mb of homozygosity in the chr15:33814680_101787650 [hg38] region of 15q14-q26.3. Patient 3 had a chromosomal karyotype of 46,XY,t(9;14)(q13;q11.2). No abnormality was found by OGM testing for patients 1 and 3.

Conclusion: As a novel cytogenetic technique, OGM can achieve high-resolution and high-precision analysis for numerical and structural genomic abnormalities. Nevertheless, it also has certain limitations, as its false negative results are related to factors such as the type of genomic variation, the chromosomal regions involved in the variation, the type of disease, and the version of human reference genome. Currently, it cannot be used as an independent method for the diagnosis of genetic diseases.

Objective: To analyze the ABO serological and molecular characteristics of a Chinese pedigree carrying an ABO*cisAB.01 allele for the blood subgroup.

Methods: A proband undergoing blood preparation for a surgery due to an open rupture of the extensor hallucis longus tendon in the left thumb on September 5, 2024 at Weihai Central Hospital and his family members were selected as study subjects. ABO serological type of six individuals from three generations was determined by serological methods. PCR was carried out to amplify exons 6 and 7 of the ABO gene, and the amplified products were directly sequenced. Samples of the proband and his mother, son, and daughter were subjected to clone sequencing analysis. This study was approved by the Medical Ethics Committee of Weihai Central Hospital (Ethics No.: LL-2024-269-01).

Results: Serological testing showed that the proband and his mother were of the AB subtype, whilst his daughter was A subtype B, his father was of O, his wife was AB, and his son was A. Direct sequencing showed that the proband's genotype was ABO*cisAB.01/O.01.02, and his mother, son, and daughter had all carried an ABO*cisAB.01 allele. There were significant differences in allelic competition when the A, B and O genes were co-dominant with the cisAB.01 allele, respectively.

Conclusion: There is allelic competition between the cisAB.01 allele and different ABO alleles. Blood type serological tests combined with molecular methods and family investigations can help ascertain and interpret the ABO blood type phenotypes.

Objective: To assess the value of Optical genome mapping (OGM) for the verification of chromosomal structural variations among patients undergoing assisting reproduction.

Methods: A retrospective analysis was carried out on the clinical data of 12 patients presented at the Reproductive Center of Ningbo University Women and Children's Hospital from October 2022 to October 2024. All patients had undergone OGM testing due to suspection of structural variants by chromosomal karyotyping or a suggestive medical history. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: EC2024-148).

Results: Among the 12 patients verified by OGM, one (8.3%) was in keeping with the result of chromosomal karyotyping. Revised karyotypes were confirmed in seven cases (58.3%), including four with complex chromosomal rearrangements. Structural variation was excluded in three cases (25.0%). Of note, OGM has identified a previously undetected cryptic balanced translocation, i.e., ogm[GRCh38] t(7;12)(q36.3;q24.23)(157511190_157523142;119205703_119198409).

Conclusion: OGM can serve as an auxiliary diagnostic technique to conventional karyotyping and enable validation of suspected structural variations in those with ambiguous karyotype results or a history of adverse pregnancies. This can provide more precise genetic diagnosis for patients undergoing assisted reproduction and selection of clinical intervention strategies.

Objective: To investigate the characteristics of chromosomal abnormalities in amniotic fluid among pregnant women in Liangshan Prefecture and explore strategies for optimizing prenatal diagnosis.

Methods: A retrospective analysis was conducted on 1 024 amniocentesis samples collected at the Prenatal Diagnosis Center of Liangshan Prefecture Maternal and Child Health Care Hospital between February 2022 and December 2024. Chromosome karyotyping analysis (3 cases had failed culture, 1 021 valid samples) was combined with high-throughput chromosome sequencing analysis (CNV-seq) for the detection. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 2023-07).

Results: The overall detection rate of chromosomal karyotype abnormalities in the amniotic fluid cells was 4.02% (41/1 021), with numerical abnormalities accounting for 80.49% (33/41) and structural abnormalities for 19.51% (8/41). Numerical abnormalities were primarily trisomy 21 (16/41, 39.02%) and 47,XXY (6/41, 14.63%). Structural abnormalities included translocations (6 cases) and mosaicism (2 cases). CNV-seq detected 22 pathogenic or likely pathogenic copy number variations, whilst the undetection rate for balanced translocations reached 100% (7/7). The combined application of karyotyping and CNV-seq, leveraging complementary strengths, can enhance the overall detection rate.

Conclusion: The distribution characteristics of chromosomal abnormalities in amniotic fluid from pregnant women in Liangshan exhibit regional specificity. A combined testing strategy significantly optimizes prenatal diagnosis efficacy, providing crucial evidence for enhancing the effectiveness of prenatal diagnosis in ethnic minority regions.

Objective: To explore the clinical presentation and genetic etiology of a case with Xeroderma pigmentosum in conjunct with basal cell carcinoma and melanoma.

Methods: A male patient with Xeroderma pigmentosum treated at Xinxiang Central Hospital in October 2022 was selected as study subject. Whole exome sequencing (WES) was carried out. Candidate variants were verified by Sanger sequencing of his family members. This study was approved by the Ethics Committee of the hospital (Ethics No.: 2021-167).

Results: Magnetic resonance imaging showed that the patient has a solid soft tissue mass in the anterior and lower part of his right eyeball and a small nodule on the left nasal wing. Histopathological biopsy showed that the periocular tumor was basal cell carcinoma in conjunct with malignant melanoma, and the nasal wing tumor was basal cell carcinoma. WES and Sanger sequencing revealed that he has harbored compound heterozygous variants of the XPC gene, namely c.2391delT (p.F797Lfs*11) and IVS1+1G>A, which were inherited from his father and mother, respectively. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variants were rated as likely pathogenic (PVS1+PM2_Supporting+PM3) and pathogenic (PVS1+PM2_Supporting+PM3+PP5), respectively. The c.2391delT variant was unreported previously. Bioinformatic analysis suggests that it could significantly affect the tertiary structure of XPC protein.

Conclusion: The c.2391delT(p.F797Lfs*11) and IVS1+1G>A compound heterozygous variants probably underlay the pathogenesis in this patient. The detection of the novel variant has enriched the mutational spectrum of the XPC gene.

Objective: To analyze the phenotype and genotype of a family with hereditary coagulation factor Ⅹ (FⅩ) deficiency and preliminarily explore its molecular pathogenesis.

Methods: A hereditary FⅩ deficiency pedigree presented at the First Affiliated Hospital of Wenzhou Medical University on August 13, 2024 was selected as the study subject. Coagulation parameters of the proband and her family members (7 individuals from 3 generations) were measured using a one-stage clotting assay. All of the 8 exons and flanking sequences of the F10 gene were amplified by PCR and directly sequenced. Bioinformatics software was used to analyze the functional impact and pathogenicity of the variant proteins, as well as the spatial conformational changes and evolutionary conservation of the mutation sites. This study has been approved by the Medical Ethics Committee of the First Affiliated Hospital of Wenzhou Medical University (Ethics No.: KY2022-R193).

Results: The proband exhibited significantly abnormal prothrombin time (PT, 33.3 s), activated partial thromboplastin time (APTT, 47.7 s), and FⅩ activity (FⅩ:C, 3%), while other coagulation parameters remained normal. The plasma thromboplastin generation test (PTGT) demonstrated that the proband and her children had lower thromboplastin generation levels compared with the healthy control group, and the proband's thromboplastin generation capacity was more severely impaired. Genetic analysis revealed that the proband, her daughter, and grandson have all harbored a heterozygous missense variant c.212T>C (p.Phe71Ser) in exon 2 of the F10 gene, which was located in the β-sheet core region of the Gla domain. The variant has altered surrounding hydrogen bonds and disrupted calcium-binding sites. Additionally, the proband, her son, and granddaughter have all carried a heterozygous missense variant c.1270G>T (p.Val424Phe) in exon 8, which increased the side-chain volume, leading to steric hindrance in the catalytic domain and impaired coagulation function. Bioinformatics analysis confirmed that both p.Phe71Ser and p.Val424Phe were pathogenic variants, with Phe71 and Val424 being highly conserved residues.

Conclusion: The reduced FⅩ levels in this hereditary FⅩ-deficient family may be attributed to the heterozygous missense variants c.212T>C (p.Phe71Ser) in the exon 2 and c.1270G>T (p.Val424Phe) in the exon 8 of the F10 gene.

Objective: To explore the clinical and genetic characteristics of a child with intellectual development disorder and seizures due to a variant of AP2M1 gene.

Methods: Clinical data of a child with intellectual development disorder and epilepsy who was admitted to the Department of Pediatric Neurology of the Third Affiliated Hospital of Zhengzhou University in January 2021 were retrospectively analyzed. Peripheral blood samples of the child and his parents were collected for whole exome sequencing. Candidate variant was verified by Sanger sequencing and pathogenicity analysis. The three-dimensional structure of the AP2M1 protein was visualized using Chimera v1.10.1 software. Pathogenicity of candidate variant was classified according to the Standards and Guidelines for the Interpretation of Sequence Variants from the American College of Medical Genetics and Genomics American College of Medical Genetics (ACMG). With "AP2M1 gene" "epilepsy" "intellectual disability" as the keywords, relevant cases were searched from CNKI, Wanfang Data knowledge service platform and PubMed databases with the search time spanning from the establishment of the database to September 2024. This study was approved by the Medical Ethics Committee of the Third Affiliated Hospital of Zhengzhou University (Ethics No.: 2020-57).

Results: The child was a 8-years-and-6-months-old boy, who could raise his head at 3 months and sit alone at 8 months old. He could not walk alone at 1 year old and underwent 2 months' rehabilitation treatment, and could walk alone and call his parents at 1-and-a-half-years-old. At 4-years-and-10-months-old, he started to have frequent seizures, manifesting as low level of consciousness, body shaking, accompanied by blinking, lasting about a few seconds several times a day and could be relieved. With the treatment of sodium valproate combined with lamotrigine, the convulsions were controlled, but his movement and cognition were lagged behind. DNA sequencing revealed that he has harbored a novel variant of the AP2M1 gene (NM_004068.3) c.508C>T (p.Arg170Trp). Sanger sequencing confirmed that both of his parents were of the wild-type. According to the guidelines from the American College for Medical Genetics and Genomics (ACMG), the variant was rated as pathogenic (PS2+PS4+PM1+PM2+PP2+PP3). The difference between the wild-type and mutant AP2M1 proteins can be clearly viewed through its three-dimensional structure. Two previous reports have included 5 cases due to the same variant. Common manifestations have included seizures (100%, 5/5), motor retardation (100%, 5/5), intellectual impairment (100%, 5/5), autism spectrum disorder (60%, 3/5), ataxia (100%, 5/5), and special facial features (20%, 1/5).

Conclusion: The c.508C>T (p.Arg170Trp) variant of the AP2M1 gene may underlie the intellectual retardation and seizure in this child.