中华医学遗传学杂志最新文献

Objective: To investigate the clinical characteristics and genetic etiology of a Chinese pedigree affected with Hereditary dentin dysplasia type II (DD-II) due to variant of dentin sialophosphoprotein (DSPP) gene.

Methods: A child diagnosed with DD- II at the Third Clinical Division of Peking University Hospital of Stomatology in December 2021 and her family members were selected as study subjects. Clinical data were retrospectively analyzed. Saliva samples were collected from the proband, her parents and sister for genomic DNA extraction. Whole exome sequencing (WES) was carried out. Candidate variant was verified by Sanger sequencing and TOPO-TA cloning sequencing. The candidate variant was also subjected to bioinformatics analysis using Mutation Taster v2021. Secondary and tertiary structures of the wild-type and variant DSPP proteins were predicted with psipred v4.0 and PyMOL v2.3 software, respectively. The pathogenicity of the variant was classified based on the guidelines from American College of Medical Genetics and Genomics (ACMG). This study was approved by the Medical Ethics Committee of Peking University Hospital of Stomatology (Ethics No.: PKUSSIRB-202162021).

Results: The proband and her mother and sister had all exhibited typical clinical manifestations of hereditary DD-II. The primary dentition of the proband displayed yellowish brown discoloration, wear, and obliteration in the chamber and root canal, while the permanent teeth of the proband's sister and mother appeared nearly normal in both color and appearance, though with obliteration in the chamber and root canal. Her father showed normal dentition. WES identified a heterozygous c.1915_1918delAAGT, p.(Lys639Glnfs*674) frameshift variant in the DSPP gene. Sanger sequencing and TOPO-TA cloning sequencing confirmed the presence of this variant in the proband, the proband's sister, and the mother, while the proband's father was negative for the variant, indicating an autosomal dominant inheritance pattern. The variant was predicted to be pathogenic by Mutation Taster v2021. Prediction of the secondary structure of the DSPP protein showed that the variant has changed it from coil to helix. The tertiary structure prediction of the DSPP protein showed change of the spatial structure of the variant DSPP, with the loops in the variant region replaced by helices at multiple sites. Based on the guidelines from the ACMG, the variant was classified as pathogenic (PVS1+PM2_Supporting+PP1+PP4).

Conclusion: Phenotypic analysis and genetic testing of this family has clarified the clinical diagnosis of hereditary DD- II. The c.1915_1918delAAGT variant probably underlay the pathogenesis of DD-II in this family. Above results have expanded the phenotypic spectrum of the disease and may contribute to further clinical and genetic research on this disease.

Objective: To explore the genetic etiology of a Chinese pedigree affected with Primary ciliary dyskinesia (PCD).

Methods: A child who presented at the ENT Department of Zhengzhou University Children's Hospital in March 2024 due to secretory otitis media, chronic sinusitis, adenoid hypertrophy, dextrocardia, and bronchiectasis was selected as study subject. Relevant clinical data were collected. Peripheral blood samples from the child and her family members were collected. Following DNA extraction, whole exome sequencing was carried out. Candidate variants were validated by Sanger sequencing, and the correlation between the variants and phenotype was analyzed. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2024-K-135).

Results: The child and her elder siblings exhibited similar clinical manifestations including recurrent cough, secretory otitis media, chronic sinusitis, tracheobronchitis, and pneumonia. The child also presented with bronchiectasis and visceral situs inversus. Genetic testing results indicated that the child and her elder siblings had all harbored compound heterozygous variants of the DNAH11 gene, namely c.3000 1G>A and c.5775C>G (p.Tyr1925*), which were respectively inherited from their phenotypically normal parents. Both variants can affect mRNA splicing and protein translation integrity. Based on the guidelines from the American College of Medical Genetics and Genomics, both variants were classified as likely pathogenic. It was predicted that they may jointly lead to a functional defect in axonemal dynein, resulting in the phenotype of PCD, conforming to an autosomal recessive inheritance.

Conclusion: The compound heterozygous variants c.3000 1G>A and c.5775C>G (p.Tyr1925*) of the DNAH11 gene probably underlay the pathogenesis of PCD in this pedigree. The same variant in different individuals may lead to different clinical phenotypes, which has reflected significant heterogeneity in genetic background and clinical phenotype. Above findings have enriched the mutational spectrum of PCD gene and have important implications for the accurate diagnosis, treatment, prognosis, and genetic counseling.

Objective: To carry out pathological and genetic analyses on a fetus with intrauterine growth restriction and death during second trimester after induced abortion.

Methods: A fetus undergone induced abortion due to intrauterine growth restriction and death during second trimester at the the Seventh Affiliated Hospital of Sun Yat-Sen University in 2024 was selected as the study subject. Clinical data of the pregnancy were collected. DNA was extracted from tissues from the aborted fetus and peripheral blood samples from its parents. Chromosomal microarray analysis and whole exome sequencing were carried out. Candidate variants were verified by Sanger sequencing. Following abortion, routine autopsy and pathological analysis were conducted. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: KY-2025-334-01).

Results: The aborted fetus was a male and harbored compound heterozygous nonsense variants of the TH gene (c.457C>T/p.Arg153* and c.694C>T/p.Gln232*), for which both parents were heterozygous carriers. Autopsy and pathological analysis revealed that the fetus had pathological features including loose arrangement of myocardial fibers and congestion in the liver.

Conclusion: Biallelic null variants of the TH gene may cause heart failure by affecting the development of cardiovascular system, which in turn may lead to intrauterine death. This study has provided new clues for the molecular diagnosis of stillbirth and recurrent pregnancy loss.

Objective: To explore the genetic basis for a boy affected with Cohen syndrome.

Methods: A boy admitted to Children's Hospital of Nanjing Medical University in January 2021 was selected as the study subject. Genome DNA was extracted from peripheral blood samples from the child and his parents. Whole exome sequencing (WES) was carried out. And candidate variants were verified by Sanger sequencing. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 202106060-1).

Results: WES revealed that the child has harbored compound heterozygous variants of the VPS13B gene, namely c.1563+1G>A and c.3007insC (p.A1003Afs*13), which were inherited from his mother and father, respectively. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were rates as pathogenic. The c.3007insC (p.A1003Afs*13) was unreported previously.

Conclusion: The compound heterozygous variants c.1563+1G>A and c.3007insC (p.A1003Afs*13) of the VPS13B gene probably underlay the pathogenesis of Cohen syndrome in this child. Above finding has enriched the mutational spectrum of VPS13B gene.

Objective: To explore the prenatal features and genetic etiology of a fetus with Short-rib cage dysplasia (SRTD) due to variants of DYNC2H1 gene.

Methods: A pregnant women presented at Xinxiang Central Hospital in June 2020 for abnormal prenatal ultrasound findings was selected as the study subject. With informed consent obtained, amniotic fluid sample was extracted from the woman, and clinical data of the fetus were collected. Whole exome sequencing (WES) was carried out, and candidate variants were verified by Sanger sequencing. This study was approved by the Medical Ethics Committee of Xinxiang Central Hospital [Ethics No.: 2025-214-01(K)].

Results: At 25⁺⁶ weeks gestation, genetic testing revealed that the fetus has harbored compound heterozygous variants of the DYNC2H1 gene, namely c.10585C>T (p.Arg3529Ter) and c.8954T>G (p.Val2985Gly), which were derived from its father and mother, respectively. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.10585C>T (p.Arg3529Ter) and c.8954T>G (p.Val2985Gly) variants were classified as pathogenic (PVS1+PM2_supporting+PM3+PP5) and likely pathogenic (PM1+PM2_supporting+PM3+PP3), respectively. Bioinformatics analysis suggested that both variants may affect the 3D structure of the DYNC2H1 protein.

Conclusion: The compound heterozygous variants of c.10585C>T (p.Arg3529Ter) and c.8954T>G (p.Val2985Gly) of the DYNC2H1 gene probably underlay the pathogenesis of SRTD in the fetus. Above findings had facilitated prenatal diagnosis and genetic counseling for the couple.

Objective: To explore the genetic etiology of a Chinese boy affected with Oculo-facio-cardio-dental syndrome (OFCD).

Methods: A child diagnosed with OFCD at West China Hospital of Sichuan University on September 21, 2024 was selected as the study subject. Clinical phenotype of the child was collected through ophthalmologic examination, cardiac ultrasonography, and X-ray imaging. Potential pathogenic variants were detected by trio-whole exome sequencing (Trio-WES). Candidate variant was validated with TA-cloning followed by Sanger sequencing. Mosaic variant was analyzed by ultra-deep sequencing (10,000-fold) and quantitative PCR. This study was approved by the Medical Ethics Committee of the West China Hospital of Sichuan University (Ethics No.: 2019-772 ).

Results: The proband had presented with congenital cataracts, mitosis, atrial and ventricular septal defects, dental abnormalities, and right radioulnar synostosis. His mother also exhibited congenital cataracts and dental anomalies, suggesting a diagnosis of OFCD. Trio-WES revealed an novel heterozygous 14-bp deletion (c.4724_4737del) in exon 12 of the BCOR gene in the proband. Deep sequencing identified a mosaic BCOR c.4724_4737del mutation in approximately 3.4% of peripheral leukocytes from his mother. Quantitative PCR analysis also confirmed the presence of this low-level mosaicism. The 14-bp deletion was predicted to cause a frame shift and premature termination (p.Met1575AsnfsTer6). Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as pathogenic (PVS1+PM2+PP1).

Conclusion: Above findings have expanded the spectrum of BCOR mutations associated with OFCD, which highlighted the role of low-level mosaicism with maternal transmission and provided a basis for genetic counseling and reproductive guidance for the family.

Objective: To explore the clinical features and genetic etiology in a child with Hereditary hemorrhagic telangiectasia (HHT) complicated by growth hormone deficiency.

Methods: A child presented at Yantai Yuhuangding Hospital in October 2014 for "short stature for over 4 years" was selected as the study subject. Peripheral venous blood samples were collected from the child and his parents for genomic DNA extraction and whole-exome sequencing (WES). The pathogenicity of the candidate variants was assessed by following the guidelines from the American College of Medical Genetics and Genomics (ACMG). This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 2025-003).

Results: The patient, a 4-year-and-2-month-old male, presented with short stature and recurrent epistaxis since early childhood. Initial diagnosis of GHD was made via growth hormone stimulation testing. During follow-up, telangiectatic macules and polycythemia gradually appeared. WES revealed that he has harbored a heterozygous c.1807G>A (p.Gly603Arg) variant of the ENG gene, which was absent in both parents and classified as likely pathogenic based on ACMG guidelines. Sanger sequencing confirmed the candidate variant to be de novo.

Conclusion: Patients with HHT combined with GHD may exhibit clinical features such as short stature, telangiectasia, and arteriovenous malformations. The heterozygous c.1807G>A (p.Gly603Arg) variant of the ENG gene probably underlay the pathogenesis of the disease in the proband. Above finding has expanded the mutational spectrum of the ENG gene.

Objective: To explore the clinical and genetic characteristics of five fetuses with Harlequin ichthyosis (HI).

Methods: Five fetuses with HI diagnosed at Guangdong Women and Children Hospital between 2017 and 2024 were selected as study subjects. Clinical and laboratory data were collected and reviewed. Whole exome sequencing (WES) was carried out, and candidate variants were verified by bioinformatic analysis. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 202401024).

Results: The five fetuses had presented with ectropion, eclabium and contracture and flexion of fingers and toes. WES revealed that all had harbored compound heterozygous or homozygous variants of the ABCA12 gene. Among the eight types of variants, five were unreported previously.

Conclusion: The compound heterozygous or homozygous variants of the ABCA12 gene probably underlay the HI in the five fetuses. Clinicians should be vigilant about the possibility of HI in fetus with ectropion, eclabium, and contracture and flexion of fingers and toes.

Objective: To investigate the clinical characteristics and genetic etiology in a fetus with 12q14 microdeletion syndrome.

Methods: A fetus diagnosed with 12q14 microdeletion syndrome at Wenzhou People's Hospital in July 2019 was selected as the study subject. The fetus was from a twin pregnancy by in vitro fertilization-embryo transfer, with ultrasound findings including growth restriction, cleft lip/palate, ventricular septal defect, tricuspid regurgitation, and pericardial effusion. Clinical data and family history were collected. Amniotic fluid sample was collected from both twins, and peripheral blood samples were obtained from their parents. Amniocytic karyotyping analysis and chromosomal microarray analysis (CMA) were performed, and familial validation was conducted. This study was approved by the Medical Ethics Committee of Wenzhou People's Hospital (Ethics No.: KY-202408-034).

Results: Prenatal ultrasound showed no significant abnormality in one of the twins, whilst the other twin exhibited severe growth restriction accompanied by cleft lip/palate, ventricular septal defect, tricuspid regurgitation, and pericardial effusion. Karyotyping and CMA analyses of first twin showed no abnormalities, whilst the second twin had a chromosomal karyotype of 46,XN,t(3;12)(q26.3;q14), and CMA revealed a 4.9 Mb deletion in the 12q14.3-q15 region (arr[hg19]12q14.3q15(65,574,059_70,488,106)x1). Karyotyping and CMA analyses of both parents revealed no abnormalities, confirming that the fetus deletion was de novo in origin. Literature review suggested that prenatal diagnosis of 12q14 microdeletion syndrome has been extremely rare.

Conclusion: The fetus was diagnosed with 12q14 microdeletion syndrome. This de novo deletion may have dervied from chromosomal translocation. As a first-tier prenatal diagnostic technique, CMA can effectively detect microdeletion/microduplications missed by conventional karyotyping analysis.

Objective: To determine the carrier rate for thalassemia mutations in the ethnic Miao population of Qianxinan Prefecture.

Methods: Ethnic Miao people suspected for thalassemia trait at the People's Hospital of Qianxinan Prefecture, Guizhou Province between November 2020 to September 2024 were selected as the study subjects. Gap-PCR technology combined with high-throughput sequencing was used to screen a total of 666 individuals. ArcMap v10.8.2 was used to create a spatial distribution map of thalassemia based on the screening results. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 2016-01).

Results: In total 254 positive cases were detected, with an overall positive rate of 38.14%. Among these, 173 cases were α-thalassemia (25.98%), 77 cases were β-thalassemia (11.56%), and 4 cases were αβ compound thalassemia (0.60%). The most common genotypes for α-thalassemia were αα/--^SEA (positive rate = 10.06%, accounting for 38.73%), αα/-α^3.7 (positive rate = 8.86%, accounting for 34.10%), and α^CSα/αα (positive rate = 4.95%, accounting for 19.08%). The most common genotypes for β-thalassemia were β^41/42(-TTCT)/β^A (positive rate = 5.11%, accounting for 44.16%) and β^{17 (A>T)}/β^A(positive rate = 4.20%, accounting for 36.36%), with these two genotypes accounting for as much as 80.52%. The spatial distribution map indicated that the highest overall detection rate of thalassemia and α-thalassemia in the Miao population of Qianxinan Prefecture was in Xingyi City. The highest detection rate of β-thalassemia was in Zhenfeng County, and the highest detection rate of αβ compound thalassemia was in Wangmo County.

Conclusion: The detection rate of thalassemia among the ethnic Miaos from Qianxinan Prefecture is relatively high, which primarily consisted of α-thalassemia. Regular monitoring and educational outreach should be conducted.