中华医学遗传学杂志最新文献

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.

Objective: To investigate the clinical phenotype and genetic etiology of a patient with primary infertility accompanied by Oocyte maturation defect (OOMD).

Methods: A 24-year-old female patient who visited the Reproductive Medicine Center of Gansu Provincial Maternity and Child Care Hospital in April 2024 was selected as the study subject. Whole-exome sequencing (WES) was performed on the proband and her husband. Candidate gene variants were validated in the family using Sanger sequencing, and compound heterozygous variants were confirmed through vector construction. Candidate variants were classified for pathogenicity according to the "Standards and Guidelines for the Interpretation of Sequence Variants" established by the American College of Medical Genetics and Genomics (ACMG). This study was approved by the Medical Ethics Committee of the Hospital [Ethics No.: (2023) GSFYLS(78)].

Results: The proband, a 24-year-old female, had been unable to conceive for four years without contraception after marriage. She had undergone two ovarian stimulation cycles using the antagonist protocol and the PPOS protocol, respectively. A total of 74 oocytes were retrieved, with all showing OOMD and some oocytes exhibiting abnormal morphology and poor quality. WES results revealed two heterozygous missense variants in exons 14 and 16 of the PATL2 gene: c.1127G>A (p.R376Q) and c.1388C>G (p.A463G). Family validation results indicated that the missense variant in exon 14 was inherited from the proband's father, while the variant in exon 16 was de novo.

Conclusion: The compound heterozygous variants of the PATL2 gene probably underlay the OOMD and infertility in this proband. Further analysis based on the variant sites and protein structures is needed to determine whether PATL2 gene variants can fully affect oocyte development, thereby providing a personalized treatment plan for the proband.

Objective: To assess the value of combined detection strategies using multiple technologies for the genetic testing and prenatal diagnosis for pedigrees affected with Duchenne muscular dystrophy (DMD) for optimizing genetic counseling and reproductive guidance.

Methods: This study has involved 142 subjects from 65 suspected DMD families who had visited the First Affiliated Hospital of Chongqing Medical University from January 2018 to December 2023. A combination of multiple ligation-dependent probe amplification (MLPA), quantitative fluorescence PCR, and next-generation sequencing (NGS) was used. After confirming the genetic diagnosis of the probands, prenatal diagnosis was provided for carrier mothers. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 2021-264).

Results: Among the 142 subjects tested, 73 cases of large deletions/duplications and 15 cases of small variants of the DMD gene were detected. The hotspot regions for the variants were exons 45 to 55. A total of 41 variant types were identified, of which 3 were previously unreported. In 19 families with suspected patients, 7 exonic deletions, 2 exonic duplications, and 3 small variants were identified. Prenatal diagnosis was performed on 48 fetuses from 46 families, revealing 16 affected male fetuses (including 12 with deletion variants, 2 with duplication variants, and 2 with small variants). Seven carrier females were identified among the 16 female fetuses (including 6 with deletions and 1 with duplication). Among the couples with an affected fetus, 16 had opted to terminate the pregnancy, while the parents of 32 fetuses had chosen to continue with the pregnancy. In families undergoing prenatal diagnosis, 53 (79.1%) pregnant women and their family members were found to carry mutations of the DMD gene.

Conclusion: The combined detection strategy of MLPA, qPCR, and NGS can encompass large deletions/duplications and small variants of the DMD gene, providing timely and accurate prenatal diagnosis for families affected by DMD. In conjunction with genetic counseling, this can effectively reduce the risk of producing affected offspring, which is crucial for the prevention and control of this disease.

Objective: To evaluate the clinical significance of a hemizygous c.1042-10G>C variant of the SLC9A7 gene NM_001257291.2) previously identified in individuals with neurodevelopmental disorders, and to provide an evidence-based guidance for prenatal genetic counseling.

Methods: Four families presented at the Medical Genetics Center of Henan Provincial People's Hospital between December 2022 and July 2024 were included in this study. Phenotypic information and biological samples were collected from family members. Genomic DNA was extracted and subjected to whole-exome sequencing and copy number variation analysis to identify candidate pathogenic variants. Sanger sequencing was performed for familial co-segregation analysis. Reverse-transcription PCR was used to assess the RNA splicing pattern of the variant in peripheral blood samples. Quantitative PCR was employed to analyze the expression profiles of various SLC9A7 transcripts in fetal brain tissue and peripheral blood samples. Pathogenicity of the variant was classified based on guidelines from the American College of Medical Genetics and Genomics (ACMG). This study was approved by the Medical Ethics Committee of Henan Provincial People's Hospital (Ethics No.: 2021-171).

Results: Six hemizygous males carrying the SLC9A7 c.1042-10G>C variant were identified among the four families, which included three adult males and two male infants with normal phenotypes. Only one affected male from family 3 exhibited global developmental delay, short neck, webbed neck, ocular dysplasia, and congenital corneal leukoma. He also had a history of perinatal asphyxia and carried an additional hemizygous variant HUWE1 c.12283C>G. Reverse-transcription PCR showed no aberrant splicing in heterozygous or hemizygous carriers compared to healthy controls, suggesting that the variant does not affect RNA splicing. Quantitative PCR revealed that NM_001257291.2 is the predominant transcript expressed in fetal brain tissue and peripheral blood.

Conclusion: The SLC9A7 c.1042-10G>C variant does not alter RNA splicing and is present in multiple phenotypically normal males, which supported its classification as a benign variant.

Objective: To explore the genetic etiology of four fetuses with Uniparental disomy (UPD), and analyze their causes.

Methods: Four fetuses undergoing prenatal diagnosis at Wenzhou Central Hospital between November 2021 and July 2024 were selected as the study subjects. Genetic testing and diagnosis were carried out through G-banded chromosomal karyotyping, single nucleotide polymorphism array (SNP-array) and methylation multiplex ligation-dependent probe amplification (MS-MLPA). This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: L2024-11-028).

Results: The four cases of pathogenic UPD had involved chromosomes 2, 11, 15 and 16, respectively, of which 2 cases were accompanied by fetal ultrasound abnormalities, One fetus was shown a high risk by serological screening, while another showed a high risk by non-invasive DNA testing. The karyotype of fetus 1 was 45,X?,rob(13;15)(q10;q10), and its parents had both carried a Robertsonian translocation involving chromosomes 13 and 15, whilst the karyotypes of other three fetuses were all normal. Pedigree analysis indicated that the UPDs in three cases were paternally derived, and the remaining one was unknown. The causes of the four cases included imprinting syndrome in two cases, autosomal recessive disorder in one case, and cryptic mosaic trisomy in one case.

Conclusion: The clinical phenotypes of UPD are diverse, and the mechanisms are complex. Combined chromosomal karyotyping, SNP-array, MS-MLPA and other technologies are required to make a clear diagnosis for prenatal genetic counseling and postnatal management.

Objective: To explore the clinical features and genetic etiology of two Chinese patients with Cowden syndrome (CS).

Methods: Two patients diagnosed with multiple gastrointestinal polyps by gastroenteroscopy at Henan Provincial People's Hospital in September and November 2023 were selected as the study subjects. Clinical data of the patients were collected. Whole exome sequence (WES) was carried out. Candidate variants were verified by Sanger sequencing. This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2018-03-01).

Results: The patients were diagnosed with multiple gastrointestinal polyps in addition with polypoid changes of the gallbladder. Genetic testing revealed that patient 1 has harbored a heterozygous c.738dupG (p.Leu247Valfs*6) variant of the PTEN gene, which was unreported previously. Patient 2 has harbored a heterozygous c.469G>T (p.Glu157Ter) variant of the PTEN gene, which was known to be pathogenic. None of their family members was found to harbor the above variants. Based on the guidelines from the American College of Medical Genetics and Genomics, both variants were rated as pathogenic (PVS1+PM2_Supporting+PP3+PP4). Bioinformatic analysis suggested that both variants can significantly affect the tertiary structure of the PTEN protein.

Conclusion: The heterozygous variants of the PTEN gene probably underlay the CS in both patients. Discovery of the novel variant has enriched the mutational spectrum of the PTEN gene.

Objective: To explore the clinical characteristics and genetic etiology of a child with Osteopathia striata with cranial sclerosis (OSCS) due to variant of AMER1 gene.

Methods: A child presented at the Affiliated Children's Hospital of Zhengzhou University in July 2024 due to growth and development retardation was selected as the study subject. A retrospective study was conducted to collect the child's clinical data. Peripheral blood samples (2 mL each) were collected from the child and her parents, and genomic DNA was extracted for whole exome sequencing (WES). Sanger sequencing was used for the verification of candidate variants. The pathogenicity of variant was rated according to the guidelines from American College of Medical Genetics and Genomics (ACMG). The study has been approved by the Medical Ethics Committee of the Children's Hospital Affiliated to Zhengzhou University (Ethics No.: 2024-108-001).

Results: The patient, a 4-year-and-10-month-old girl, presented with global developmental delay, short stature, cleft palate, distinct facial features, and hearing impairment. WES revealed that she has harbored a heterozygous c.790_794dup (p.Cys265Trpfs*19) variant of the AMER1 gene, which was not detected in either parent. Based on the guidelines from ACMG, the gene variant was classified as pathogenic (PVS1 + PS2 + PM2_supporting). As the result of a non-triplet base insertion in the coding region of the AMER1 gene, it has converted a codon originally encoding an amino acid into a stop codon, and led to a truncated protein, causing severe alteration and dysfunction of the protein.

Conclusion: The child was diagnosed with OSCS for clinical features such as global developmental delay, short stature, cleft palate, distinctive facial features, and hearing impairment, for which the de novo heterozygous frameshift variant AMER1: c.790_794dup (p.Cys265Trpfs*19) may be accountable. Above finding has expanded the mutational spectrum of OSCS and provided a basis for genetic counseling and prenatal diagnosis for the family.

Objective: To assess the association of single nucleotide polymorphisms (SNP) of the cell division cycle 42 (CDC42) gene with Pulmonary artery systolic pressure (PASP) among patients with Congenital heart disease (CHD).

Methods: In this observational study, clinical data and blood samples were collected from 579 CHD patients with left-to-right shunt who presented to our hospital between January 2012 and January 2017. SNPs of the CDC42 gene were genotyped using an improved multiple ligase detection reaction. Multiple linear regression was applied to evaluate the association of CDC42 gene variants with PASP. This study was approved by the Medical Ethics Committee of the First Affiliated Hospital of Xinjiang Medical University (Ethics No.: 20180222-102).

Results: Polymorphisms at rs2501256 and rs34896897 of the CDC42 gene were significantly associated with PASP. Compared with the CC genotype at rs2501256, TT and CT carriers displayed higher PASP [TT vs. CC: B (95%CI) = 4.01 (1.95, 6.07), P < 0.001; CT vs. CC: B (95%CI) = 2.91 (0.63, 5.19), P < 0.001]. Similarly, GG and GA genotypes at rs34896897 were associated with higher PASP compared to the AA genotype [GG vs. AA: B (95%CI) = 26.15 (20.45, 31.84), P < 0.001; GA vs. AA: B (95%CI) = 7.19 (4.31, 10.08), P < 0.001]. Genetic model analyses demonstrated significant differences for both rs2501256 and rs34896897 under dominant, additive, and recessive models (P < 0.05). TT carriers at rs2501256 exhibited larger left-and right-atrial diameters, whereas GG carriers at rs34896897 showed greater right-atrial and right-ventricular end-diastolic dimensions. Subgroup analyses revealed no association between rs2501256 and PASP in males, individuals younger than 18 years, Uyghur ethnicity, or those with ventricular septal defects.

Conclusion: CHD patients carrying the minor alleles of rs2501256 and rs34896897 in the CDC42 gene present higher incidence of PASP compared to those carrying the common alleles.