中华医学遗传学杂志最新文献

Objective: To analyze the correlation between variants in the start codon of the α-globin gene and phenotypes of thalassemia, so as to provide a basis for the diagnosis and prevention of α-thalassemia.

Methods: A retrospective study was conducted on 7 patients diagnosed by Yangjiang People's Hospital and Guangzhou Hybribio Co. Ltd., from June 2019 to October 2022. Routine blood tests and hemoglobin electrophoresis were carried out. Potential variants were identified through polymerase chain reaction (PCR) combined with Reverse dot blotting (RDB), Gap-PCR, and Sanger sequencing. This study has been approved by the Medical Ethics Committee of People's Hospital of Yangjiang (Ethics No: 20240001).

Results: For the 7 patients, results of blood routine test of one case was unknown, and that of another was normal. The remaining 5 cases had presented with microcytic hypochromic anemia. The results of hemoglobin electrophoresis showed that one case had normal Hb A and slightly lower Hb A2, whilst another had significantly decreased Hb A and Hb A2, in addition with the appearance of a Hb H band. The content of Hb Bart's in four neonates was ≥ 0.4%. The remaining one case had no result. Genetic testing has identified 4 rare start codon mutations, namely HBA2: c.2delT, HBA2: c.1A>G, HBA2: c.1A>T, and HBA1: c.2T>C. Among these, Patient 1 had harbored compound heterozygous variants of HBA2: c.427T>C (Hb CS) and HBA2: c.2delT. Patient 4 had harbored compound heterozygous variants of HBA2: c.1A>G and Southeast Asian type deletion.

Conclusion: Heterozygotes with HBA start codon variants usually present as silent or mild thalassemia, and the symptoms of anemia may deteriorate when combined with other α-thalassemia variant. The HBA2: c.1A>T start codon variant was unreported previously in China. The detection of start codon variants has helped to clarify the causes of anemia, genetic counseling, and guidance for reproduction.

Antisense oligonucleotide (ASO) was discovered several decades ago and initially used only as a research tool in the laboratory. In recent years, several ASO therapeutics have been developed for neurological disorders. Some of these therapeutics, including eteplirsen, golodirsen, viltolarsen, nusinersen and inotersen, have been approved by the Food and Drug Administration (FDA) and begun to draw the public's attention as an effective therapeutic approach. These novel therapeutics have shown great performance, while many similar therapeutics are under investigation and in clinical trials. This n-of-1 precision medicine may start a new chapter in the paradigm of therapeutics. Clinicians, clinical geneticists, and genetic counselors may know about this novel therapy, but very few may understand the background in details. During genetic counseling, they have the responsibility to convey the effectiveness, side effects and cost of such therapies to patients and their families. As these target therapies will require precise genetic diagnosis before treatment, healthcare professionals and genetic counselors play a vital role in relating the patients to the corresponding ASO drugs. This review has elaborated the mechanism of ASO therapies, including basic rationales, modifications, side effects and delivery routes. It also systemically summarized the FDA-approved ASO therapeutics and their applications for various neurological disorders, and discussed the limitations and challenges the real-world market may face and issues genetic counselor should take into consideration in the near future.

Objective: To explore the clinical manifestations and genetic characteristics of a child with Leukoencephalopathy with ataxia (LKPAT) caused by a CLCN2 gene variant.

Methods: A retrospective analysis was conducted on the clinical data of a child admitted to Hunan Children's Hospital in June 2024 due to "intermittent convulsions for 13 days". Peripheral blood samples were collected from the child and his parents for whole exome sequencing, followed by Sanger sequencing validation and pathogenicity analysis of candidate variants. Literature searches were performed using the keywords "CLCN2 gene" "chloride channel-2" "leukoencephalopathy with ataxia/LKPAT" "leukoencephalopathy" in both Chinese and English on CNKI, Wanfang, and PubMed databases. The search time was set from the establishment of the databases to July 31, 2024. Childhood-onset LKPAT literature was screened and analyzed. This study was approved by the Medical Ethics Committee of Hunan Children's Hospital (Ethics No. HCHLL-2024-351).

Results: The child was a 7-month-and-26-day-old male infant born to consanguineous parents, presenting with epileptic seizures and borderline development. Cranial MRI revealed symmetrical long T₂ signal shadows in the posterior limb of the internal capsule, cerebral peduncle, pons, and middle peduncle of the cerebellum. Video electroencephalogram (EEG) showed an abnormal childhood EEG with one focal seizure. Whole exome sequencing revealed a homozygous c.2201dup (p.Glu735Ter) variant in the CLCN2 gene of the child. Sanger sequencing confirmed that the variant was inherited from both parents. According to the guidelines of the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP), this variant was classified as pathogenic (PVS1+PM3_Supporting+PM2_Supporting). A total of 8 relevant literature were retrieved, together with the present case, 16 childhood-onset LKPAT patients were cumulatively reported, which consisted of 9 males and 7 females. Twelve CLCN2 gene variants were involved, including 2 nonsense variants, 3 missense variants, 7 frameshifting variants, 2 c.61dup variants, and 5 c.1709G>A variants. The initial symptoms of the 16 patients included headache, ataxia, epileptic seizures, spasticity, developmental delay, lower back pain, hearing impairment, and intention tremor. Three patients had onset of the disease before the age of one, of which 2 had epileptic seizures as the initial symptom.

Conclusion: The homozygous variant CLCN2: c.2201dup (p.Glu735Ter) is considered the pathogenic cause of LKPAT in this child, marking the first childhood-onset case reported in China. Genetic testing has facilitated the diagnosis of childhood-onset LKPAT and expanded the spectrum of CLCN2 gene mutations.

Objective: To explore the genotype-phenotype correlation in a Charcot-Marie-Tooth type 2A2A (CMT2A2A) pedigree and to provide genetic counseling for its subsequent pregnancies.

Methods: A Chinese pedigree presenting with "lower limb muscle atrophy and movement disorders" at the Prenatal Diagnosis Center of Xuzhou Central Hospital between January and August 2024 was selected as the study subject. Relevant clinical data were collected from the pedigree members. Peripheral blood samples from affected individuals, and amniotic fluid and/or chorionic villus samples were obtained for DNA extraction. Whole exome sequencing (WES) was carried out. Candidate variants were verified by Sanger sequencing. Pathogenicity assessment and bioinformatic analysis were conducted. This study was approved by the Medical Ethics Committee of Xuzhou Central Hospital (Ethics No. XZXY-LK-20240111-0019).

Results: All affected individuals in this pedigree were females, whom included the proband, her mother, and her first daughter. Earlier age of onset was associated with more severe lower limb atrophy. A heterozygous missense variant of the MFN2 gene, namely c.314C>T (p.Thr105Met), was identified in the proband, her mother, daughter, and the third fetus from a re-marriage. The same variant was absent in her elder brother, current husband, and her fourth fetus. Based on the guidelines from American College of Medical Genetics and Genomics (ACMG) and recommendations from Clinical Genome Resources (ClinGen), the variant was classified as pathogenic (PP1_Strong+PM1+PS3+PS4_Moderate+PP3_Moderate+PM2_Supporting). Analyses with PROVEAN and Mutation Taster had categorized the variant as "deleterious" and "disease-causing", respectively. Analysis with Uniprot and Jalview showed that the affected amino acid residue is conserved across multiple species. ChEBI software predicted that the variant may alter the polarity of the 105th amino acid residue.

Conclusion: The c.314C>T (p.Thr105Met) missense variant of the MFN2 gene probably underlie the CMT2A2A in this pedigree. Above finding has enabled prenatal diagnosis and genetic counseling for its subsequent pregnancies.

Objective: To explore the clinical significance of trisomy 7 signaled by non-invasive prenatal testing (NIPT).

Methods: Pregnant women with high risk for trisomy 7 by NIPT from January 2017 to December 2023 were selected as the study subjects, and the results of prenatal diagnosis and follow-up were analyzed. Literature related to pregnant women with a high risk for trisomy 7 by NIPT from January 2016 to July 2024 was retrieved from China Biomedical Literature Database, Wanfang Database, China National Knowledge Infrastructure and PubMed database. Relevant information such as the incidence of trisomy 7 by NIPT, positive predictive value (PPV), and pregnancy outcomes were collected. This study has been approved by the Medical Ethics Committee of Lianyungang Maternal and Child Health Care Hospital (Ethics No. JS2022010).

Results: A total of 51 women with a high risk for trisomy 7 by NIPT were identified. Thirty-two of them had chosen chromosomal microarray analysis (CMA) of amniotic fluid cells, and 1 case of mosaic trisomy 7 was detected, which had yielded a PPV of 3.13%. Four women had opted termination of pregnancy, 1 had miscarriage, 4 had pre-term and/or low weight birth, whilst the remaining 42 (82.4%) had full-term delivery. In total 19 literature were retrieved, which had involved 278 cases of trisomy 7 signaled by NIPT, among which 5 fetuses with mosaic trisomy 7 (3.14%) were confirmed. Among the 211 women with follow-up outcomes, 2 (0.95%) had intrauterine growth restriction, 3 (1.42%) had abnormal fetal structure detected by ultrasound, 2 (0.95%) had miscarriage, 9 (4.27%) underwent pregnancy termination, 28 (13.27%) had preterm and/or low weight birth, whilst 167 (79.14%) had normal delivery. In 18 cases, chromosomal analysis of placental tissue was carried out, and 17 were confirmed to have mosaicism trisomy 7.

Conclusion: The PPV for trisomy 7 signaled by NIPT is extremely low. Although most of such women had a full term delivery, adverse pregnancy outcomes may still occur in a minority of cases. Clinicians should provide adequate genetic counseling for such women and recommend appropriate prenatal diagnosis strategies and optimal perinatal management plans.

Epigenetics is the link between the genome and environment, which can respond to physiological (such as age) or environmental factors (such as diet, stress, and pollution) and induce changes in epigenetic modifications (such as DNA methylation, non-coding RNA, and histone modifications). It can also serve as cellular memory transmitted from generation to generation. Sperm is highly responsive to such environmental changes and has unique epigenetic profiles. The paternal inter-/trans-generational inheritance mediated by sperm epigenetic changes is closely related to the health of offspring, which is an issue of great concern. This review has summarized the epigenetic mechanisms of paternal inter-/trans-generational inheritance and recent studies on the paternal inheritance mediated by sperm epigenetic changes in human and mice, which may facilitate understanding of the relationship between paternal epigenetic changes and the health of offspring caused by physiological or environmental changes and provide a basis for genetic counseling and clinical intervention.

Objective: To explore the results of four types of Urea cycle disorders (UCDs) in newborns from the Xuzhou region, assess the efficacy of newborn screening by tandem mass spectrometry (MS/MS), and analyze their genetic characteristics.

Methods: A retrospective analysis was performed using tandem mass spectrometry to screen for inherited metabolic disorders in 691 712 newborns at the Maternal and Child Health Care Hospital of Xuzhou from November 2015 to December 2023. Ten children (cases 1-10) were diagnosed with Ornithine transcarbamylase deficiency (OTCD), Carbamoylphosphate synthase 1 deficiency (CPS1D), Arginase deficiency (ARGD), and Argininosuccinate synthase deficiency (ASSD) based on MS/MS and genetic testing. This study was approved by the Medical Ethics Committee of Xuzhou Maternity and Child Health Care Hospital (Ethics No.XZFY2024-051K-01J).

Results: A total of 691 712 neonates were screened for UCDs using MS/MS, which identified 1 237, 1 237, 510, and 1 009 initial positive cases for OTCD, CPS1D, ASSD, and ARGD, respectively. After genetic testing, 1 case of OTCD, 1 case of CPS1D, 1 case of ASSD, and 7 cases of ARGD were confirmed. The overall positive predictive value for these four UCDs was 0.362%. Among the 10 diagnosed UCD cases, four novel variants were identified, which included OTC: c.1024C>A (p.L342M) and ASS1: c.826A>G (p.M276V), c.695C>T (p.P232L) and c.694C>T (p.P232S). Bioinformatic analysis has rated these as variants of uncertain clinical significance or likely pathogenic based on guidelines from the American College of Medical Genetics and Genomics (ACMG).

Conclusion: The incidence of four UCDs in neonates from the Xuzhou area is relatively low, and there is a correlation between genetic variants and clinical phenotypes. For novel variants with uncertain clinical significance or suspected pathogenicity, their pathogenicity should be clarified in conjunction with clinical and biochemical indicators. The four novel pathogenic variants of UCDs identified in this study have enriched the mutational spectrum of UCDs-associated genes in the Xuzhou region.

Objective: To explore the clinical features of a child with Lamb-Shaffer syndrome (LAMSHF) due to a variant of SOX5 gene.

Methods: A child who was admitted to Children's Hospital Affiliated to Zhengzhou University in July 2022 was selected as the study subject. Clinical data of the child was collected. Whole exome sequencing (WES) was carried out on peripheral blood samples from the child and his parents, and candidate variant was verified by Sanger sequencing and bioinformatic analysis. The study has been approved by the Medical Ethics Committee of the Children's Hospital Affiliated to Zhengzhou University (Ethics No. 2024-K-100).

Results: The child, an one-year-and-seven-month-old male, has manifested delayed development in speech and language, intelligence and movement, in addition with mild facial deformities and eye signs. Whole exome sequencing revealed that he has harbored a heterozygous c.1828_1829insGACT (p.Y610fs*1) frameshifting variant of the SOX5 gene. Sanger sequencing confirmed the variant to be de novo in origin. The variant was also unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was rated as pathogenic (PVS1+PS2+PM2_supporting).

Conclusion: The c.1828_1829insGACT (p.Y610fs*1) variant of the SOX5 gene probably underlay the pathogenesis of LAMSHF in this child. For children with delayed mental, language, intellectual, and motor development, genetic testing should be conducted to facilitate early diagnosis. Above finding has enriched the mutational spectrum of the SOX5 gene.

Pancreatitis is an inflammatory disease influenced by both environmental and genetic factors. It has a high prevalence and mortality rate worldwide, with no radical cure. Breakthroughs have been recently made in genetic research of pancreatitis. Susceptibility genes and pathways have been continuously discovered, which highlighted the roles of genetic factors in hypertriglyceridemic and chronic pancreatitis. Gene therapy may offer radical cure for pancreatitis, though it has remained at the research phase. This article has reviewed the genetic pathogenesis of pancreatitis and current status of gene therapy research, with an aim to provide a reference for attaining definitive cure for the disease.