中华医学遗传学杂志最新文献

Objective: To explore the genetic characteristics of a Chinese pedigree with rare mosaic 11q partial duplication and its pathogenetic mechanisms.

Methods: A pedigree which underwent prenatal diagnosis at Wenzhou Central Hospital between September 25, 2015 and November 30, 2023 was selected for the study. Clinical data were collected from the pedigree. Peripheral blood samples from the parents, amniotic fluid from the fetus, and peripheral blood sample from the neonate were obtained. Genetic testing was carried out by using G-banded chromosomal karyotyping and single nucleotide polymorphism array (SNP-array) technology. Relevant literature was searched in the CNKI, Wanfang Data Knowledge Service Platform, and PubMed databases to summarize the clinical phenotypes of patients with 11q partial duplication. This study was approved by the Medical Ethics Committee of Wenzhou Central Hospital (Ethics No. L2024-07-080).

Results: The pregnant woman (G₃) had a history of adverse pregnancy outcomes. During her first pregnancy (G₁), prenatal ultrasound indicated intrauterine growth restriction and a Dandy-Walker variant. Follow-up at 8 years of age showed developmental delays and mild intellectual disability. During her second pregnancy (G₂), prenatal ultrasound revealed nasal bone hypoplasia, and the pregnancy was terminated at 23rd gestational week. During her third pregnancy (G₃), all prenatal tests were normal, and the neonate showed normal growth and development at 4 months of age. The karyotype of amniotic fluid of her first pregnancy was 46,X?, and the SNP-array analysis of neonatal peripheral blood showed arr[GRCh37/hg19]11q13.4q25(70432450_134607121)×2~3, with a mosaicism rate being approximately 40%. The karyotype for her second pregnancy was 46,X?,rec(11)dup(11q)inv(11)(p15q13)dmat[6]/46,X?[27], and the SNP-array result was arr[GRCh38]11q13.4q25(71406636_135067522)×2~3, with a mosaicism rate being approximately 75%. The karyotype for her third pregnancy was 46,X?,inv(11)(p15q13)mat, and the SNP-array result was arr(XN)×1,(1~22)×2. The karyotype of the woman was 46,XX,inv(11)(p15q13), and that of her husband was 46,XY. A review of 12 similar cases (including G₁) from the literature revealed that the common clinical phenotypes of 11q partial duplication included intellectual disability (12/12), developmental delay (12/12), ear abnormalities (12/12), microcephaly (10/12), seizures (8/12), hypotonia (8/12), and congenital heart malformations (7/12).

Conclusion: Mosaic partial duplication of 11q may underlie the genetic etiology of this pedigree. The pregnant woman is a carrier of an inversion on chromosome 11, which might have formed the mosaic 11q partial duplication through meiotic errors and mitotic trisomy rescue mechanisms during reproduction.

Next generation sequencing (NGS) technology is playing an increasingly important role in the diagnosis of genetic diseases. Whole exome sequencing (WES) which targets the coding regions of the genome has been widely used in the diagnosis of genetic diseases for its low cost and high efficiency. However, compared to conventional methods, the NGS process is intricate, and there is variability in the expertise of data analysts and variant interpreters, which may lead to inconsistencies in the outcomes. To ensure the quality of testing and enhance the diagnostic rate of diseases, this consensus has provided recommendations regarding the laboratory setup, operational procedures, data analysis, result interpretation, and quality control for WES, with an aim to standardize its application in the detection of genetic disorders.

Objective: To explore the clinical phenotype, pregnancy outcome and follow-up of fetuses with 15q11.2BP1-BP2 microdeletions in order to provide a basis for prenatal and reproductive consultation.

Methods: From March 2019 to December 2023, 20 fetuses who were diagnosed with 15q11.2BP1-BP2 microdeletion syndrome at the Prenatal Diagnosis Center of General Hospital of Ningxia Medical University were selected as the study subjects. Results of genetic testing and ultrasound examination, outcome of pregnancy, and postnatal follow-up were retrospectively analyzed. This study has been approved by the Ethics Committee of General Hospital of Ningxia Medical University ([2020]0520B).

Results: None of the 20 fetuses was found to have chromosomal abnormality, whilst all were found to harbor a 15q11.2 BP1-BP2 microdeletion by low-depth whole genome sequencing (CNV-seq). The range of deletions was determined as 0.26 ~ 0.87 Mb, and all were rated as pathogenic CNVs. Three fetuses had abnormal ultrasound findings, including 1 with widened renal pelvis, 1 with agenesis of corpus callosum, and 1 with nuchal fold thickening. Parental verification in 10 couples verified that two fetal deletions were de novo, whilst the remaining eight were inherited from a phenotypically normal parent. Following genetic counseling, three couples had opted to terminate the pregnancy, whilst the remaining 17 had continued with the pregnancy until delivery. The 17 liveborns were followed up for 2 months to 5 years, with no obvious abnormality in growth and development noted.

Conclusion: CNV-seq plays an important role in the prenatal diagnosis of 15q11.2 BP1-BP2 microdeletions. Such deletions may not always lead to disease phenotypes. Individualized consultation and long-term follow-up, in combination with intrauterine ultrasound and parental verification are necessary.

Objective: To explore the genetic etiology of a child with Nemaline myopathy (NM).

Methods: A child who had visited Fujian Children's Hospital on January 28, 2023 due to "phlegm in the throat for more than a month" was selected as the study subject. Clinical data of the child was collected, in addition with peripheral blood samples from her and her parents. Following extraction of genomic DNA, trio-whole exome sequencing (WES) was carried out. Candidate variants was verified by Sanger sequencing and bioinformatic analysis. This study has been approved by the Medical Ethics Committee of Fujian Children's Hospital (Ethic No. 2023ETKLRK2004).

Results: The patient, a 2-month-old female, had presented with persistent phlegm in the throat, recurrent severe pneumonia, swallowing difficulty, and decreased muscle tone. WES results revealed that she has harbored compound heterozygous variants of the NEB (NM_001271208.1) gene, namely c.4611+2T>A and c.12961del (p.Ser4321ALafs*21), and the associated disease is rod-like myopathy. Sanger sequencing confirms that the variants were respectively inherited from her mother and father, both of whom had normal phenotypes. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were rated as likely pathogenic (PVS1_Moderate+PM2_Supporting+PM3; PVS1+PM2_Supporting).

Conclusion: The c.4611+2T>A/c.12961del (p.Ser4321ALafs*21) compound heterozygous variants of the NEB gene probably underlay the pathogenesis in this child. Above findings has facilitated the diagnosis, genetic counseling, and guidance for reproductive decision of her family.

Objective: To report on the phenotype of an adult patient with 2p23.2p22.1 duplication and explore its genotype-phenotype correlation.

Methods: A pregnant woman who had presented at the Affiliated Drum Tower Hospital of Nanjing University Medical School on January 12, 2024 for a high risk signaled by NIPT was selected as the study subject. Amniotic fluid and peripheral blood samples were collected and subjected to chromosomal microarray analysis (CMA). The phenotype of the patient was observed, the medical history was taken, combined with the result of CMA assay, relevant database was searched for similar cases reported in the literature, and the correlation between genotype and phenotype was analyzed.

Results: The CMA result of the patient was arr[GRCh38]2p23.2p22.1(27961669_39280633)×3, which indicated a 11.31 Mb duplication. The woman was found to have short stature, learning disability, visual deficit, sleep disorder and other disorders.

Conclusion: The duplication of PPP1CB and SOS1 genes within the 2p23.2p22.1 region can result in Noonan syndrome-like clinical manifestations such as short stature and reduced visual acuity. The duplication of the PPP1CB gene may be associated with the abnormal visual phenotype.

Objective: To explore the clinical phenotype and genetic characteristics of two siblings with intellectual disability.

Methods: Clinical data and peripheral blood samples were collected from the proband, his younger sister and parents whom had presented at Wenzhou Central Hospital in February 2024. Low-coverage massively parallel copy number variation sequencing (CNV-seq) and whole exome sequencing (WES) were carried out for the family. Candidate variants were verified by Sanger sequencing. Prenatal diagnosis was performed on a fetus upon the couple's subsequent pregnancy. The study was approved by the Medical Ethics Committee of Wenzhou Central Hospital (Ethic No. L2024-07-001).

Results: The proband was a 12-year-old boy who had presented with mental retardation and language delay. His 10-year-old sister also manifested delayed mental and motor development. Whole exome sequencing revealed that the proband and his sister had respectively harbored a novel heterozygous c.3549_3550del (p.Glu1183Aspfs*29) variant of the TRIP12 gene and a novel heterozygous c.99del (p.Ser34Alafs*38) variant of the GRIN2B gene. Sanger sequencing confirmed that both variants had a de novo origin. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were classified as pathogenic (PVS1+PS2_Supporting+PM2_Supporting). Neither variant was found to be carried by the fetus upon prenatal diagnosis.

Conclusion: Above variants probably underlay the mental disorders in the two siblings, and the concurrent occurrence of two novel pathogenic variants in a family has been extremely rare.

Objective: To summarize the results of prenatal diagnosis and outcome of pregnancy of fetuses with a high risk for 6p22.1.1-p21.32 duplication signaled by non-invasive prenatal screening (NIPS).

Methods: Clinical information, results of prenatal diagnosis and pregnancy for fetuses with a high risk for 6p22.1-p21.32 duplication were collected and analyzed. This study has been approved by the Medical Ethics Committee of the First Affiliated Hospital of Zhengzhou University (Ethic No. 2018-YB-08).

Results: Forty three pregnant women with a high risk for 6p22.1-p21.32 duplication were identified by NIPS, among whom 30 had accepted invasive prenatal diagnosis, and 27 fetuses were verified to be false positive. Three fetuses were found to have other chromosomal abnormalities, among whom two were rated to be likely benign CNV and 1 was rated to be likely pathogenic. Follow up of the 43 pregnant women revealed that 35 fetuses were normal after birth, 1 pregnancy was terminated, and 7 were lost to follow up.

Conclusion: For pregnant women with a high risk for 6p22.1-p21.32 duplication signaled by NIPS, genetic counselor need to inform them the high false positive rate and recommend invasive prenatal diagnosis and/or ultrasound examination in order to reduce the psychological and economic burdens.

Optical genome mapping (OGM) is an emerging technology for the detection of genetic diseases based on physical mapping, which can detect numerical chromosomal abnormalities, copy number variation (CNV) and structural variation (SV) on a genome-wide scale. In recent years, a number of studies have proved that OGM, as a new generation of cytogenomic technique, has higher resolution and stronger ability to discover genomic variants compared with conventional genetic techniques. This article has systematically reviewed the principles, characteristics, advantages and limitations of OGM technology, and its applications in the diagnosis of genetic disorders.

Objective: To explore the clinical phenotypes and genetic variant in a neonatal case of Mitochondrial DNA depletion syndrome type 13 (MTDPS13).

Methods: Clinical data and results of genetic testing of a neonate admitted to the Children's Hospital of Zhejiang University School of Medicine in January 2023 was retrospectively analyzed. The study was approved by the Medical Ethics Committee of the Children's Hospital of Zhejiang University.

Results: The male infant was admitted to the NICU due to tachypnea and persistent lactic acidosis 6 hours after birth. At admission, distinctive facial features were noted. Laboratory tests showed elevated lactic acid (< 30 mmol/L). Whole-exome sequencing revealed that he has harbored homozygous c.141del frameshift mutation of FBXL4 gene, which was unreported previously. The mutation was inherited from both of his parents and classified as likely pathogenic based on the guidelines from the American College of Medical Genetics and Genomics (ACMG).

Conclusion: The clinical phenotypes of this case of MTDPS13 is characterized by lactic acidosis, distinctive facial features, growth retardation and developmental delay, for which the homozygous c.141del variant of the FBXL4 gene may be accountable.