[Genetic analysis of a case of mild epilepsy due to variant of SCN9A gene].

OBJECTIVE: To explore the genetic etiology of a patient with epilepsy and provide genetic counseling. METHODS: A patient who had visited the Center for Reproductive Medicine of Shandong University on November 11, 2020 was selected as the study subject, and her clinic information was collected. Candidate variant was identified through whole exome sequencing (WES), and Sanger sequencing was used for validation. Possible transcriptional changes caused by the variant was detected by reverse transcription-PCR and Sanger sequencing. RESULTS: The patient was a 35-year-old female with no fever at the onset, loss of consciousness and abnormal firing in the temporal lobe, manifesting predominantly as convulsions and fainting. WES revealed that she had harbored a heterozygous c.2841+5G>A variant of the SCN9A gene, which was verified by Sanger sequencing. cDNA sequencing confirmed that 154 bases were inserted between exons 16 and 17 of the SCN9A gene, which probably produced a truncated protein and affected the normal function of the SCN9A protein. Based on the guidelines from the American College of Medical Genetics and Genomics, the c.2841+5G>A variant was classified as likely pathogenic (PVS1_Strong+PM2_Supporting). CONCLUSION: The c.2841+5G>A variant of the SCN9A gene probably underlay the epilepsy in this patient. Above finding has enriched the variant spectrum of the SCN9A gene and provided a basis for the prenatal diagnosis and preimplantation genetic testing for this patient.

Carbon Transfer Decision Model Based on LMDI Method.

Establishing a coordinated governance mechanism for regional carbon emissions is an essential way to achieve carbon peak and carbon neutrality, while the study of interprovincial carbon emissions transfer is one of the important foundations of regional carbon emissions coordinated governance research. Based on the multiregional input-output (MRIO) model, this study calculated the carbon emissions from both the producers' perspective and the consumers' perspective and analyzed the interprovincial net carbon emissions transfer decision. Furthermore, the logarithmic mean Divisia index (LMDI) method was adopted to decompose the factors that affect the province's net carbon emissions into technological effect, structural effect, input-output effect, and scale effect. It was revealed that the input-output effect was the primary influencing factor of the net carbon transfer at the provincial level.

[Identification of a novel variant of NHS gene underlying Nance-Horan syndrome].

OBJECTIVE: To explore the genetic basis for a pedigree affected with Nance-Horan syndrome. METHODS: Clinical manifestation of the patients was analyzed. Genomic DNA was extracted from peripheral blood samples of the pedigree members and 100 unrelated healthy controls. A panel of genes for congenital cataract was subjected to next-generation sequencing (NGS), and candidate variant was verified by Sanger sequencing and bioinformatic analysis based on guidelines of American College of Medical Genetics and Genomics (ACMG). mRNA expression was determined by reverse transcriptase-PCR (RT-PCR). Linkage analysis based on short tandem repeats was carried out to confirm the consanguinity. RESULTS: A small insertional variant c.766dupC (p.Leu256Profs*21) of the NHS gene was identified in the proband and his affected mother, but not among unaffected members and the 100 healthy controls. The variant was unreported in Human Gene Mutation Database (HGMD) and other databases. Based on the ACMG guideline, the variant is predicted to be pathogenic (PVS1+PM2+PM6+PP4). CONCLUSION: The novel variant c.766dupC of the NHS gene probably underlay the X-linked dominant Nance-Horan syndrome in this pedigree.

[A case of tuberous sclerosis complex due to a novel splicing variant of TSC2 gene].

OBJECTIVE: To explore the genetic basis for a patient with tuberous sclerosis complex. METHODS: Genomic DNA was extracted from peripheral blood samples from members of his family and 100 unrelated healthy controls. The proband was subjected to next-generation sequencing, and candidate variant was confirmed by multiple ligation-dependent probe amplification (MLPA) and Sanger sequencing. Reverse transcription-PCR (RT-PCR) was carried out to determine the relative mRNA expression in the proband. RESULTS: The patient was found to harbor a c.2355+1G>C splicing variant of the TSC2 gene. Sequencing of cDNA confirmed that 62 bases have been inserted into the 3' end of exon 21, which has caused a frameshift producing a truncated protein. CONCLUSION: The novel splicing variant c.2355+1G>C of the TSC2 gene probably underlay the TSC in the proband. Above finding has expanded the variant spectrum of TSC2 and provided a basis for preimplantation genetic testing and/or prenatal diagnosis.

A nonsense variant in FBN1 caused autosomal dominant Marfan syndrome in a Chinese family: a case report.

BACKGROUND: Marfan syndrome (MFS) is a common autosomal dominant inherited disease, and the occurrence rate is around 0.1-0.2‰. The causative variant of FNB1 gene accounts for approximately 70-80% of all MFS cases. In this study, we found a heterozygous c.3217G > T (p.Glu1073*) nonsense variant in the FBN1 gene. This finding extended the variant spectrum of the FBN1 gene and will provide a solution for patients to bear healthy offspring by preimplantation genetic testing or prenatal diagnosis. CASE PRESENTATION: The patient was treated due to tachycardia during excitement in a hospital. Echocardiography showed dilatation of the ascending aorta and main pulmonary artery, mitral regurgitation (mild), tricuspid regurgitation (mild), and abnormal left ventricular filling. Electrocardiograph showed sinus rhythm. In addition, flutters of shadows in front of his eyes and vitreous opacity were present in the patient. Genomic DNA was extracted from peripheral blood samples from members of the family and 100 unrelated controls. Potential variants were screened out by next-generation sequencing and confirmed by MLPA & Sanger sequencing. Real-time fluorescence quantitative PCR (RT-qPCR) was performed to detect the relative mRNA quantitation in the patient. A heterozygous nonsense variant c.3217G > T of the FBN1 gene, which resulted in p. Glu1073Term, was identified in both patients. Only wild type bases were found in the cDNA sequence of the patient. Real-time fluorogenic quantitative PCR results showed that the relative expression level of FBN1 cDNA in the patient was only about 21% compared to that of normal individuals. This variant c.3217G > T of the FBN1 gene introduces a Stop codon in the cb-EGF12 domain. We speculated that a premature translational-termination codon (PTC) was located in the mRNA and the target mRNA was disintegrated through a process known as nonsense-mediated mRNA decay (NMD), which led to a significant decrease of the fibrillin-1 protein, eventually causing clinical symptoms in the patient. CONCLUSIONS: In this study, we found a heterozygous c.3217G > T (p.Glu1073*) nonsense variant in the FBN1 gene, which eventually led to Marfan syndrome in a Chinese family.

[Analysis of MECP2 gene variants in three pedigrees affected with Rett syndrome].

OBJECTIVE: To detect potential variants of MECP2 gene in three pedigrees affected with Rett syndrome (RTT). METHODS: All exons and their flanking regions of the MECP2 gene were subjected to Sanger sequencing and multiplex ligation-dependent probe amplification assay. RESULTS: The probands of pedigrees 1 and 2 have respectively carried a c.965C>G and a c.1157_1197del41 variant of the MECP2 gene, while the proband of pedigree 3 carried a heterozygous deletional variant in exon 4 of the MECP2 gene. CONCLUSION: Variants of the MECP2 gene probably underlay the RTT in the three pedigrees. Above finding has enriched the spectrum of MECP2 gene variants, and provided a guidance for the patients upon preimplantation genetic testing and prenatal diagnosis.

[Identification of a novel variant of COL4A5 gene in a pedigree affected with Alport syndrome].

OBJECTIVE: To explore the genetic basis for a pedigree affected with Alport syndrome. METHODS: Next generation sequencing and Sanger sequencing was carried out to detect potential variant of the COL4A5 gene among members from the pedigree and 100 unrelated healthy controls. RESULTS: A novel missense c.3293G>T (p.Gly1098Val) variant was found in the COL4A5 gene among 6 affected members but not the unaffected members of the pedigree or the 100 healthy controls. According to the American College of Medical Genetics and Genomics standards and guidelines, the c.3293G>T variant was classified as pathogenic (PP1-strong+PM1+PM2+PP3+PP4). CONCLUSION: By destructing the Gly-X-Y structure of its protein product, the c.3293G>T variant of the COL4A5 gene probably underlies the Alport syndrome in this pedigree. Above finding has enriched the spectrum of COL4A5 variants.

[Identification of a novel splicing variant of IDS gene in a pedigree affected with type II glycosaminoglycan product storage disease].

OBJECTIVE: To analyze variant of IDS gene in a pedigree affected with mucopolysaccharidosis type II (MPS II). METHODS: The proband was subjected to next generation sequencing and Sanger sequencing to identify potential variants. Suspected variant was analyzed by its co-segregation with the disease in the pedigree. Its impact on mRNA splicing was analyzed by using reverse transcription PCR (RT-PCR). RESULTS: A hemizygous IVS1-3T>G variant was found in the IDS gene in the proband. RT-PCR results revealed two abnormal cDNA fragments of 600 bp and 300 bp. The 600 bp fragment had inserted 216 nucleotides at the 3' end of intron 1, while the 300 bp fragment had lost 109 nucleotides at the 5' end of exon 2, which resulted in two truncated proteins comprising 38 and 92 amino acids, respectively, instead of the normal product (550 amino acids). The proband and his mother were respectively hemizygous and heterozygous for the variant. The same variant was not found among 100 normal controls. CONCLUSION: The IVS1-3T>G variant of the IDS gene probably underlies the MPS II in this pedigree by causing reduction or elimination of the IDS protein.

Complex preimplantation genetic tests for Robertsonian translocation, HLA, and X-linked hyper IgM syndrome caused by a novel mutation of CD40LG gene.

PURPOSE: To perform complex preimplantation genetic tests (PGT) for aneuploidy screening, Robertsonian translocation, HLA-matching, and X-linked hyper IgM syndrome (XHIGM) caused by a novel mutation c.156 G>T of CD40LG gene. METHODS: Reverse transcription PCR (RT-PCR) and Sanger sequencing were carried out to confirm the causative variant of CD40LG gene in the proband and parents. Day 5 and D6 blastocysts, obtained by in vitro fertilization (IVF) with intracytoplasmic sperm injection, underwent trophectoderm (TE) biopsy and whole genomic amplification (WGA) and next generation sequencing (NGS)-based PGT to detect the presence of a maternal CD40LG mutation, aneuploidy, Robertsonian translocation carrier, and human leukocyte antigen (HLA) haplotype. RESULTS: Sanger sequencing data of the genomic DNA showed that the proband has a hemizygous variant of c. 156 G>T in the CD40LG gene, while his mother has a heterozygous variant at the same position. Complementary DNA (cDNA) of CD40LG amplification and sequencing displayed that no cDNA of CD40LG was found in proband, while only wild-type cDNA of CD40LG was amplified in the mother. PGT results showed that only one of the six tested embryos is free of the variant c.156 G>T and aneuploidy and having the consistent HLA type as the proband. Meanwhile, the embryo is a Robertsonian translocation carrier. The embryo was transplanted into the mother's uterus. Amniotic fluid testing results are consistent with that of PGT. A healthy baby girl was delivered, and the peripheral blood testing data was also consistent with the testing results of transplanted embryo. CONCLUSIONS: The novel mutation of c. 156 G>T in CD40LG gene probably leads to XHIGM by nonsense-meditated mRNA decay (NMD), and complex PGT of preimplantation genetic testing for monogenic disease (PGT-M), aneuploidy (PGT-A), structural rearrangement (PGT-SR), and HLA-matching (PGT-HLA) can be performed in pedigree with both X-linked hyper IgM syndrome and Robertsonian translocation.

A Novel Splicing Mutation in the FBN2 Gene in a Family With Congenital Contractural Arachnodactyly.

Congenital contractural arachnodactyly (CCA) is an extremely rare monogenic disorder in humans, and the prevalence of CCA is estimated to be less than 1 in 10,000 worldwide. CCA is characterized by arachnodactyly, camptodactyly, the contracture of major joints, scoliosis, pectus deformities, and crumpled ears. Mutations in FBN2 (which encodes fibrillin-2) are responsible for causing this disease. A family with CCA was investigated in this study, and a novel variant, c.3724+3A > C (also identified as IVS28+3A > C), in FBN2 was found in nine patients from the family but was not found in seven unaffected relatives. Reverse transcription-PCR (RT-PCR) and complementary DNA (cDNA) sequencing data showed that exon 28 was skipped in the FBN2 gene. The FBN2 c.3724+3A > C variant led to an in-frame deletion during transcription, which eventually triggered CCA in the Chinese family.

[Novel mutations of XPC gene detected in a family affected with xeroderma pigmentosum group C].

OBJECTIVE: To detect mutations of the XPC (XPC complex subunit, DNA damage recognition and repair factor) gene in a family affected with xeroderma pigmentosum group C (XP-C). METHODS: The patient was subjected to next-generation sequencing and Sanger sequencing. Suspected mutations were validated by Sanger sequencing. Effect of splicing mutation was confirmed by reverse transcription-PCR (RT-PCR). RESULTS: Compound heterozygous mutations of c.2098G to T and c.2034-7_2040del were found in the XPC gene in the proband. Among these, c.2098G to T (p.G700X) is a nonsense mutation resulting in a truncated XPC protein. C.2034-7_2040del involves the -1 position, which may alter the splice donor site of the intron 11 of XPC and result in a truncated XPC protein with loss of amino acids from 940 to 679 positions. The two mutations were not detected among 100 unrelated healthy controls. CONCLUSION: Mutations of c.2098 G to T and c.2034-7_2040del of the XPC gene may lead to abnormal XPC expression and reduction or elimination of normal XPC functions, which may underlie the disease in this family.