Pontocerebellar hypoplasia type 2D caused by compound heterozygous variants in the SEPSECS gene: A case report and literature review

The use of fetal exome sequencing in prenatal diagnosis: a points to consider document of the American College of Medical Genetics and Genomics (ACMG)

ACMG SF v3.0 list for reporting of secondary findings in clinical exome and genome sequencing: a policy statement of the American College of Medical Genetics and Genomics (ACMG)

DNA-based screening and population health: a points to consider statement for programs and sponsoring organizations from the American College of Medical Genetics and Genomics (ACMG)

Updated recommendations for CFTR carrier screening: A position statement of the American College of Medical Genetics and Genomics (ACMG)

One is the loneliest number: genotypic matchmaking using the electronic health record

To explore the genetic etiology of a fetus with cryptophthalmos detected by prenatal ultrasonography. A fetus undergoing induced labor at 32nd gestational week due to absence of bilateral eye fissures detected by prenatal ultrasonography in January 2017 was selected as the study subject. Umbilical cord blood sample from the fetus and peripheral blood samples from its parents were collected for the extraction of genomic DNA. Pathogenic variants were screened through whole exome sequencing (WES) and verified by Sanger sequencing. Pathogenicity of candidate variants was verified by bioinformatic analysis and protein structure simulation. Based on the results of genetic testing, prenatal diagnosis was provided to the couple upon their subsequent pregnancy. The couple had four adverse pregnancies previously. The aborted fetus was the fifth, with fused bilateral upper and lower eyelids, poorly developed eyeballs, adhesion of the cornea with the upper eyelid, low-set ears, and abnormal plantar creases, and was diagnosed with cryptophthalmos. WES and Sanger sequencing revealed that the fetus has harbored compound heterozygous variants of the FREM2 gene, namely c.4537G>A (p.D1513N) and c.7292C>T (p.T2431M). Both variants were unreported associated with cryptophthalmos previously. Protein structure simulation showed that they may lead to loss of hydrogen bonds in the protein product. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were predicted to be likely pathogenic (PM1_Supporting+PM2_Supporting+PM5+PP3+PP4; PM2_Supporting+PM3+PP3+PP4). The mother was performed prenatal diagnosis in her sixth pregnancy based on the variants detected in this family, and delivered a daughter with normal phenotype. The FREM2: c.4537G>A and c.7292C>T compound heterozygous variants probably underlay the pathogenesis of cryptophthalmos in this fetus. Above finding has enriched the mutational spectrum of the FREM2 gene.

The use of ACMG secondary findings recommendations for general population screening: a policy statement of the American College of Medical Genetics and Genomics (ACMG)

Autosomal recessive non-syndromic hearing loss (ARNSHL) is a highly heterogeneous disease, for which more than 70 genes have been identified. MYO15A mutations have been reported to cause congenital severe-to-profound HL. In this study, we applied the whole exome sequencing (WES) to find the cause of HL in an Iranian family. A proband from an Iranian non-consanguineous family with hearing impaired parents, was examined via WES, after excluding GJB2 mutations as the most common ARNSHL gene via Sanger sequencing. Co-segregation analysis of the candidate variant was done in the family members. Interpretation of variants was according to the American College of Medical Genetics and Genomics (ACMG) guidelines. WES results showed novel compound heterozygous variants (p.Arg1507Ter and p.Val2815Valfs*10) in the MYO15A gene. These two variants, residing in highly conserved regions, were found to be co-segregating in the family and fulfill the criteria of being categorized as pathogenic, according to the ACMG guidelines. Here, we report successful application of WES to identify the molecular pathogenesis of ARNSHL in a patient with ARNSHL, as an example of an extremely heterogeneous disease. In agreement with previous studies, MYO15A is regarded to be important in causing HL in Iran.

To explore the clinical phenotype and genetic characteristics of a child with Hypotrichosis 14. A child who had presented at the Henan Provincial People's Hospital on May 4, 2020 due to hair thinning was selected as the study subject. Clinical data of the child was collected. Peripheral venous blood samples were collected from the child and her parents. Genomic DNA was extracted and subjected to whole exome sequencing. Candidate variants were validated by Sanger sequencing and bioinformatic analysis. The child, a 5-year-old female, had presented with thin, soft lanugo-like hair which was easy to fall off. The child was found to harbor compound heterozygous missense variants of the LSS gene, namely c.1609G>A (p.V537M) in exon 17 and c.802T>G (p.F268V) in exon 8, which were respectively inherited from her father and mother. Both variant sites were highly conserved, though based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were rated as variants of unknown significance (PM2_Supporting+PP3+PP4). The c.1609G>A (p.V537M) and c.802T>G (p.F268V) compound heterozygous variants of the LSS gene probably underlay the clinical phenotype in this patient.

To carry out prenatal diagnosis for a fetus with Meckel syndrome (MKS) and explore its genetic basis. A pregnant woman presented at Suzhou Municipal Hospital in February 2018 was selected as the study subject. Clinical data was collected. Muscle tissue sample from the abortus and peripheral blood samples from the couple were collected. Genomic DNA was extracted and subjected to chromosomal microarray analysis (CMA) and whole exome sequencing. Candidate variant was verified by Sanger sequencing. The fetus was found to have microcephaly, oligohydramnios, polycystic kidneys and banana-shaped cerebellum at 18 weeks of gestation. After induction of labor, it was found to have encephalocele, renal cysts and polydactyly. CMA has found no abnormality. Whole exome sequencing revealed novel compound heterozygous variants c.296delA (p.Lys99SerfsTer6) and c.1243G>A (p.Val415Met) in the TMEM67 gene. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.296delA variant was predicted to be pathogenic (PVS1+PM2_Supporting+PP4), whilst the c.1243G>A variant was predicted to be likely pathogenic (PM2_Supporting+PM3+PP3_Moderate+PP4). The c.296delA and c.1243G>A compound heterozygous variants of the TMEM67 gene probably underlay the MKS in this fetus.

To explore the clinical characteristics and variant of FBP1 gene in a child with Fructose-1,6-bisphosphatase deficiency (FBP1D), and review the literature on the clinical characteristics and gene mutations of FBP1D in the Chinese population. A FBP1D proband due to variant of FBP1 gene who was admitted to Women and Children's Hospital of Ningbo University on August 10, 2021 due to "vomiting for 1 day" was selected as the study subject. Clinical data of the child were retrospectively collected. Whole exome sequencing (WES) was performed on the child, and candidate variants identified in the child were validated by Sanger sequencing in both the child and his parents. The difference between wild type and variant FBP1 protein were compared using AlphaFold v3.0.1 and PyMOL v2.5.6. The pathogenicity of candidate variant was rated according to the Standards and Guidelines for the Interpretation of Sequence Variants released by American College of Medical Genetics and Genomics (ACMG) (hereinafter referred to as ACMG guidelines). Using keywords such as "FBP1 gene" and "fructose-1,6-bisphosphatase deficiency" both in Chinese and English, relevant literature on FBP1D patients caused by FBP1 gene variants in the Chinese population were retrieved from the PubMed database, CNKI, and Wanfang Data Knowledge Service Platform, and the genetic variant and clinical phenotypes of FBP1D patients reported in the literature were analyzed. The literature retrieval time was set from the establishment of each database to October 31st, 2024. This study was approved by the Women and Children's Hospital of Ningbo University (Ethics No.: 2020-048). The proband was presented with repeated infections, nausea, vomiting, and mental illness. The auxiliary examination revealed hypoglycemia, acidosis, liver and kidney dysfunction, hyperlipidemia and hepatomegaly. WES and Sanger sequencing revealed that the child has harbored compound heterozygous variants of the FBP1 gene, including a de novo nonsense variant c.778G>T (p.G260*) in exon 6 and a maternally derived missense variant c.923C>G (p.P308R) in exon 7. The c.923C>G was known as a likely pathogenic variant, while c.778G>T has not been included in the databases such as HGMD, ClinVar, 1000 Genomes, ExAC, dbSNP, and gnomAD. Protein structure prediction shows that the c.778G>T (p.G260*) variant may result in a premature termination codon, resulting in loss of a β-fold in a core region, which may significantly reduce the stability of its protein product and affect its function. Based on the ACMG guidelines, the c.778G>T (p.G260*) variant was rated as likely pathogenic (PVS1_Strong+PM2_Supporting+PP4+PM6). Literature review has identified 32 patients from 23 Chinese families with FBP1D due to FBP1 gene variants. Together with the case reported in this study, in total 33 patients were analyzed. Among them, 22 cases were males (66.7%) with hypoglycemia, metabolic acidosis, vomiting, seizures, hyperlactatemia, and ketosis as the primary clinical phenotypes. After treatment, only 1 case (3.0%) died due to cerebral hernia, while the remaining 32 (97.0%) had favorable outcomes. Four cases (12.1%) exhibited developmental delay. A total of 66 FBP1 gene variant sites were identified, which involved 22 variant types, predominantly missense mutations (31 gene variant sites). These variants were mainly located in exon 7 of the gene (25 variant sites), with c.490G>A (16.7%, 11/66), c.960_961insG (19.7%, 13/66), c.355G>A (12.1%, 8/66), and c.704delC (9.1%, 6/66) being the most common variants. The heterozygous variant of the FBP1 gene probably underlay the FBP1D in this child. Above finding has enriched the phenotypic and mutational spectrum of the FBP1 gene and provided a basis for genetic counseling and clinical decision-making.

To explore the clinical phenotype and variants of KIF4A gene associated with X-linked intellectual disability type 100 (XLID100) in a child by whole-exome sequencing (WES). A child presented at the Children's Hospital Affiliated to Nanjing Medical University in September 2023 was selected as the study subject. Clinical data of the child was retrospectively analyzed. Peripheral blood samples were collected from the child and his family members for WES analysis. Candidate variant was verified by Sanger sequencing. Pathogenicity of the candidate variant was rated based on the guidelines from the American College of Medical Genetics and Genomics (ACMG). The variant was also searched in dbSNP, OMIM, HGMD, ClinVar and gnomAD databases. Amino acid sequences of the KIF4A protein across various species were retrieved from the Ensembl Genome Browser Database and analyzed using Clustal Omega software. Relevant literature on KIF4A gene mutations associated with XLID100 was reviewed. This study has been approved by the Medical Ethics Committee of the Hospital (Ethics No. 202402022-1). The child, a 3-year-6-month-old male, had manifested intellectual impairment, language delay, autism, and choroid cyst revealed by cranial magnetic resonance imaging. No facial dysmorphism, tooth anomaly, gross motor development delay or regression, and history of seizure and febrile convulsion was noted. WES revealed that he has harbored a c.3385delinsTATC (p.Thr1129delinsTyrPro) variant of the KIF4A gene. Sanger sequencing confirmed that his mother and sister have harbored the same variant, whilst his father was of the wild type. Both of his parents had a normal phenotype. The variant was classified as of uncertain significance based on the guidelines from the ACMG. It was not recorded by the dbSNP, OMIM, HGMD, ClinVar and the gnomAD database. Conservative analysis suggested that the variant site, which normally encodes a cysteine, is highly conserved among various species. A review of the literature had retrieved 6 relevant articles documenting a total of 27 cases of KIF4A gene mutations, with only one case from China. The c.3385delinsTATC (p.Thr1129delinsTyrPro) variant of the KIF4A gene probably underlay the XLID100 in this child. Above finding has provided a reference for the clinical diagnosis and genetic counseling and enriched the mutation spectrum of the KIF4A gene.

To investigate the clinical phenotype and genetic basis of a child with epilepsy and global developmental delay. A child with epilepsy and global developmental delay who had visited West China Second University Hospital, Sichuan University on April 1, 2021 was selected as the study subject. Clinical data of the child were reviewed. Genomic DNA was extracted from peripheral blood samples of the child and his parents. Whole exome sequencing (WES) was carried out for the child, and candidate variant was verified by Sanger sequencing and bioinformatic analysis. A literature review was also carried out by searching databases such as Wanfang data knowledge service platform, China National Knowledge Infrastructure, PubMed, ClinVar and Embase to summarize the clinical phenotypes and genotypes of the affected children. The child was a 2-year-and-2-month-old male with epilepsy, global developmental delay and macrocephaly. Results of WES showed that the child has harbored a c.1427T>C variant of the PAK1 gene. Sanger sequencing confirmed that neither of his parents has carried the same variant. Only one similar case had been recorded by the dbSNP, OMIM, HGMD, and ClinVar databases. No frequency for this variant among Asian population was available in the ExAC, 1000 Genomes, and gnomAD databases. Prediction with IFT, PolyPhen-2, LRT, Mutation Taster, and FATHMM online software suggested that this variant is deleterious to the function of encoded protein. Based on the Standards and Guidelines for the Interpretation of Sequence Variants: A Joint Consensus Recommendation of the American College of Medical Genetics and Genomics (ACMG), the PAK1 gene c.1427T>C variant was determined to be likely pathogenic. The PAK1 gene c.1427T>C variant probably underlay the epilepsy and global developmental delay in this child, which has provided a reference for the clinical diagnosis and genetic counseling in children with similar disorders.

Does the law require reinterpretation and return of revised genomic results?

To explore the genetic etiology of a child with Spastic paraplegia and psychomotor retardation with or without seizures (SPPRS). A child who was admitted to the Children's Hospital Affiliated to Nanjing Medical University in April 2022 for motor developmental delay, intellectual disability, and hypertonia was selected as the study subject. Relevant clinical data were retrospectively analyzed. Whole exome sequencing (WES) was carried out for the child and his parents. Candidate variants were searched in the Single Nucleotide Polymorphism Database (dbSNP) and Online Mendelian Inheritance in Man (OMIM) database. Pathogenicity of the variants was assessed based on guidelines from the American College of Medical Genetics and Genomics (ACMG). Using key words such as "HACE1 gene" "Spastic paraplegia and psychomotor retardation with or without seizures" and "SPPRS", previous reports on SPPRS patients due to HACE1 gene variants were retrieved from the CNKI, Wanfang Data Knowledge Service Platform, CQVIP, and PubMed databases, with the time set from January 1, 2000 to April 7, 2024. A mutation map for the HACE1 protein in the patients was created. This study was approved by the Ethics Committee of the Children's Hospital Affiliated to Nanjing Medical University (Ethics No. 202404008-1). The clinical manifestations of the child had included motor developmental delay, intellectual disability and hypertonia. Magnetic resonance imaging revealed hypoplasia of posterior corpus callosum and splenium, with slight enlargement of lateral ventricles. WES revealed that the child has harbored compound heterozygous variants of the HACE1 gene, namely c.535(exon7)_c.538(exon7)delACAG (p.T179fs*5) and c.1678+2(IVS15)T>C, which were respectively inherited from his parents. Based on the guidelines from the ACMG, the variants were respectively rated as likely pathogenic (PVS1 + PM2_Supporting) and pathogenic (PVS1 + PM2_Supporting + PM3). Literature search has identified 8 papers, which reported 23 SPPRS cases due to HACE1 gene variants. All patients exhibited psychomotor developmental delay, among whom 18 HACE1 gene variants were identified. The c.535(exon7)_c.538(exon7)delACAG (p.T179fs*5) and c.1678+2(IVS15)T>C compound heterozygous variants of the HACE1 gene probably underlay the pathogenesis of SPPRS in this child. Above discovery has enriched the mutational and phenotypic spectrum of the HACE1 gene and provided a reference for clinical diagnosis and genetic counseling.