Zellweger syndrome caused by PEX6 gene variation in 2 cases and literature review / 中华儿科杂志

Objective: To summarize the clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation. Methods: This was a case series research. Clinical date and genetic results of 2 neonatal cases of Zellweger syndrome caused by PEX6 gene variation in Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology and Affiliated Hospital of Guangdong Medical University from July 2021 to July 2022 were retrospectively collected and analyzed. Literature up to August 2023 was searched from electronic databases of China National Knowledge Infrastructure (CNKI), Wanfang Data and PubMed with the combined keywords of "Zellweger syndrome" "Zellweger spectrum disorder", and "PEX6 gene" both in Chinese and English. The main clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation were summarized. Results: The 2 male neonates both developed clinical manifestations as dyspnea, hypotonia, feeding difficulties, enlarged fontanelle, and high palatine arch after birth. Biochemical parameters indicated elevated bile acids, and the cranial ultrasound showed the enlarged bilateral ventricles and subependymal cyst in both 2 neonates. Zellweger syndrome was confirmed by whole exome sequencing, and the results revealed PEX6 gene variation in the 2 neonates, including compound heterozygous variants c.315G>A and c.2095-3T>G, and homozygous variant c.506_507del. Case 1 was hospitalized for 5 days, and case 2 for 32 days; they both died shortly after being discharged (the specific time is unknown). Literature review found 26 patients, including 2 neonates in this study, with Zellweger spectrum disorder caused by PEX6 gene defect reported in 1 Chinese article and 11 English articles. Clinical features included hearing loss (19 cases), developmental delay (19 cases), vision impairment (19 cases), elevated very long chain fatty acids (17 cases), brain malformations (15 cases), hypotonia (12 cases), hepatic insufficiency (12 cases), distinctive facies (10 cases), and dental impairment (9 cases). Compound heterozygous variations dominated the variation types (15 cases), and the frameshift variations (16 cases) were the main pathogenic variations. Conclusions: Zellweger spectrum disorder should be considered when neonates show hypotonia, feeding difficulty, distinctive facial appearance, brain malformations and failure of hearing screening, or when older children show retinitis pigmentosa, sensorineural hearing loss, amelogenesis imperfecta and developmental delays. Detection of genetic variation in the PEX gene is crucial for definitive diagnosis.

A case of mental retardation caused by a frameshift variant of SYNGAP1 gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a child with mental retardation.@*METHODS@#Whole exome sequencing was carried out for the child. Candidate variant was screened based on his clinical features and verified by Sanger sequencing.@*RESULTS@#The child was found to harbor a c.995_1002delAGACAAAA(p.Asp332AlafsTer84) frameshift variant in the SYNGAP1 gene. Bioinformatic analysis suggested it to be pathogenic. The same variant was not detected in either parent.@*CONCLUSION@#The c.995_1002delAGACAAAA(p.Asp332AlafsTer84) frameshift variant of the SYNGAP1 gene probably underlay the mental retardation in this child. Above finding has expanded the spectrum of SYNGAP1 gene variants and provided a basis for the diagnosis and treatment for this child.

Analysis of clinical features and variants of NF1 gene in 12 patients with Neurofibromatosis type 1 / 中华医学遗传学杂志

OBJECTIVE@#To explore the types of NF1 gene variants and clinical characteristics among patients with Neurofibromatosis type I (NF1).@*METHODS@#Clinical data of 12 patients diagnosed at Ningbo Women and Children's Hospital between December 2019 and May 2022 were retrospectively analyzed. The probands and their family members were subjected to high-throughput sequencing, and candidate variants were verified by Sanger sequencing and chromosome microarray analysis.@*RESULTS@#The 12 patients had ranged from 4 months to 27 years old, with a male-to-female ratio of 2 : 1. Cafè-au-lait spots were found in all patients. 83.3% of them also had axillary and/or inguinal freckling, 58.3% had neurofibromas, and 16.7% had congenital pseudarthrosis of the tibia. Five types of NF1 gene variants were identified in the patients, including 5 nonsense variants, 4 frameshift variants, 1 missense variant, 1 splice variant, 1 large deletion involving the whole gene. Six patients were found to harbor de novo variants, 2 had inherited the variants from their parents, and 4 were not verified for their parental origin. The c.3379del (p.Thr1127Glnfs*15) and c.6628_6629del (p.Glu2210Thrfs*10) variants were unreported in literature and databases.@*CONCLUSION@#Most NF1 patients may present with Cafè-au-lait spots initially and are due to pathogenic variant of the NF1 gene. High-throughput sequencing can efficiently identify such variants among the patients and enable the definite diagnosis.

Genetic testing and clinical analysis of a patient with Dilated cardiomyopathy due to variant of FLNC gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a patient with Dilated cardiomyopathy.@*METHODS@#A patient admitted to Beijing Anzhen Hospital Affiliated to Capital Medical University in April 2022 was selected as the study subject. Clinical data and family history of the patient was collected. Targeted exome sequencing was carried out. Candidate variant was verified by Sanger sequencing and bioinformatic analysis based on guidelines of the American College of Medical Genetics and Genomics (ACMG).@*RESULTS@#DNA sequencing revealed that the patient has harbored a heterozygous c.5044dupG frameshift variant of the FLNC gene. Based on the ACMG guidelines, the variant was predicted to be likely pathogenic (PVS1+PM2_Supporting+PP4).@*CONCLUSION@#The heterozygous c.5044dupG variant of the FLNC gene probably underlay the pathogenesis in this patient, which has provided a basis for the genetic counseling for his family.

Analysis of PKD2 gene variant and protein localization in a pedigree affected with polycystic kidney disease / 中华医学遗传学杂志

OBJECTIVE@#To detect the mutation site in a pedigree affected with autosomal dominant polycystic kidney disease (ADPKD) and verify its impact on the protein function.@*METHODS@#Peripheral blood samples were collected from the proband and his pedigree members for the extraction of genomic DNA. Mutational analysis was performed on the proband through whole-exome sequencing. Suspected variant was verified by Sanger sequencing. A series of molecular methods including PCR amplification, restriction enzyme digestion, ligation and transformation were also used to construct wild-type and mutant eukaryotic expression vectors of the PKD2 gene, which were transfected into HEK293T and HeLa cells for the observation of protein expression and cell localization.@*RESULTS@#The proband was found to harbor a c.2051dupA (p. Tyr684Ter) frame shift mutation of the PKD2 gene, which caused repeat of the 2051st nucleotide of its cDNA sequence and a truncated protein. Immunofluorescence experiment showed that the localization of the mutant protein within the cell was altered compared with the wild-type, which may be due to deletion of the C-terminus of the PKD2 gene.@*CONCLUSION@#The c.2051dupA (p. Tyr684Ter) mutation of the PKD2 gene probably underlay the pathogenesis of ADPKD in this pedigree.

Identification of a novel DGUOK variant in a Chinese family affected with mitochondrial DNA depletion syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the molecular etiology for a Chinese family with mitochondrial DNA depletion syndrome.@*METHODS@#Genomic DNA was extracted from peripheral blood samples of the patient and her parents.Targeted capture and next-generation sequencing was carried out to detect potential variants. Suspected variant was validated by Sanger sequencing.@*RESULTS@#A novel homozygous frameshift variant c.505_508delTATC was identified in the patient, for which both his mother and father were carriers.@*CONCLUSION@#The frameshift variant c.505_508delTATC probably underlies the mitochondrial DNA depletion syndrome in this patient. The result also enriched the variant spectrum of DGUOK gene.

Analysis of AVPR2 variant in a neonate with congenital nephrogenic diabetes insipidus / 中华医学遗传学杂志

OBJECTIVE@#To detect potential variant in a male neonate affected with congenital nephrogenic diabetes insipidus (CNDI).@*METHODS@#Clinical data of the patient was collected. Genomic DNA was extracted from peripheral blood samples from the child and his parents. The whole coding regions of the arginine vasopressin V2 receptor (AVPR2) gene were amplified by PCR and subjected to Sanger sequencing.@*RESULTS@#The patient presented recurrent fever and polyuria after birth. Multiple blood gas analyses indicated hypernatremia. Ultrasound showed bilateral hydronephrosis and hydroureter. The patient was partially responsive to hydrochlorothiazide. DNA analysis identified a hemizygous frameshift variant c.890-899delACCCGGAGGC in exon 2 of the AVPR2 gene in the proband. His mother was heterozygous for the same variant.@*CONCLUSION@#The c.890-899delACCCGGAGGC variant of the AVPR2 gene probably underlies the CNDI in the child. Above discovery has enriched to spectrum of CNDI associated variants.

Genetic analysis and clinical phenotype of a family with lymphedema-distichiasis syndrome / 浙江大学学报·医学版

OBJECTIVE@#To identify the genetic causes of a family with lymphedema-distichiasis syndrome (LDS).@*METHODS@#The whole exome sequencing was performed in a aborted fetus as the proband, and a candidate gene was identified. Peripheral blood of 8 family members were collected. Genotypic-phenotypic analysis were carried out through PCR amplification and Sanger sequencing.@*RESULTS@#The proband, and the mother, grandmother, uncle, granduncle of the proband all had distichiasis or varix of lower limb carried a @*CONCLUSIONS@#The

Founder Mutations for Early Onset Melanoma as Revealed by Whole Exome Sequencing Suggests That This is Not Associated with the Increasing Incidence of Melanoma in Poland / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Germline mutations within melanoma susceptibility genes are present only in minority of melanoma patients and it is expected that additional genes will be discovered with next generation sequence technology and whole-exome sequencing (WES). MATERIALS AND METHODS: Herein we performed WES on a cohort of 96 unrelated Polish patients with melanoma diagnosed under the age of 40 years who all screened negative for the presence of CDKN2A variants. A replication study using a set of 1,200 melanoma patient DNA samples and similarly large series of healthy controls was undertaken. RESULTS: We selected 21 potentially deleterious variants in 20 genes (VRK1, MYCT1, DNAH14, CASC3, MS4A12, PRC1, WWOX, CARD6, EXO5, CASC3, CASP8AP2, STK33, SAMD11, CNDP2, CPNE1, EFCAB6, CABLES1, LEKR1, NUDT17, and RRP15), which were identified by WES and confirmed by Sanger sequencing for an association study. Evaluation of the allele distribution among carriers and their relatives in available family trios revealed that these variants were unlikely to account for many familial cases of melanoma. Replication study revealed no statistically significant differences between cases and controls. CONCLUSION: Although most of the changes seemed to be neutral we could not exclude an association between variants in VRK1, CREB3L3, EXO5, and STK33 with melanoma risk.

Two Compound Heterozygous Were Identified in SLC26A4 Gene in Two Chinese Families With Enlarged Vestibular Aqueduct

OBJECTIVES: To investigate the genetic causes of hearing loss with enlarged vestibular aqueduct (EVA) in two children from unrelated two Chinese families. METHODS: Sanger sequencing of all coding exons in SLC26A4 (encoding Pendrin protein) was performed on the two patients, their sibling and parents respectively. To predict and visualize the potential functional outcome of the novel variant, model building, structure analysis, and in silico analysis were further conducted. RESULTS: The results showed that the proband from family I harbored a compound heterozygote of SLC26A4 c.1174A>T (p.N392Y) mutation and c.1181delTCT (p.F394del) variant in exon 10, potentially altering Pendrin protein structure. In family II, the proband was identified in compound heterozygosity with a known mutation of c.919-2A>G in the splice site of intron 7 and a novel mutation of c.1023insC in exon 9, which results in a frameshift and translational termination, consequently leading to truncated Pendrin protein. Sequence homology analysis indicated that all the mutations localized at high conservation sites, which emphasized the significance of these mutations on Pendrin spatial organization and function. CONCLUSION: In summary, this study revealed two compound heterozygous mutations (c.1174A>T/c.1181delTCT; c.919- 2A>G/c.1023insC) in Pendrin protein, which might account for the deafness of the two probands clinically diagnosed with EVA. Thus this study contributes to improve understanding of the causes of hearing loss associated with EVA and develop a more scientific screening strategy for deafness.

Genetic analysis and prenatal diagnosis of a sporadic family with neurofibromatosis type 1 / 浙江大学学报·医学版

OBJECTIVE@#To identify pathogenic mutation for a family with neurofibromatosis type 1(NF1) and provide prenatal diagnosis for them.@*METHODS@#Mutation analysis of the sporadic family with NF1 was performed with target captured next generation sequencing and Sanger sequencing. RNA samples were extracted from the lymphocytes of NF1 patient and her parents. RT-PCR and Sanger sequencing were performed to analyze the relative mRNA expression in the samples. Prenatal diagnosis of the pathogenic mutation was offered to the fetus.@*RESULTS@#A novel splicing mutation c.1260+4A>T in the gene was found in the proband of the family, but was not found in her parents.cDNA sequencing showed that 13 bases inserted into the 3' end of exon 11 in the gene lead to a frameshift mutation. Prenatal diagnosis suggested that the fetus did not carried the mutant.@*CONCLUSIONS@#The : c.1260+4A>T mutation found in the NF1 patient is considered to be pathogenic, which provides information for family genetic counseling and prenatal diagnosis.

A frameshift mutation in exon 19 of MLH1 in a Chinese Lynch syndrome family: a pedigree study / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Lynch syndrome (LS), an autosomal dominantly inherited disease previously known as hereditary non-polyposis colorectal cancer (HNPCC), leads to a high risk of colorectal cancer (CRC) as well as malignancy at certain sites including endometrium, ovary, stomach, and small bowel (Hampel et al., 2008; Lynch et al., 2009). Clinically, LS is considered the most common hereditary CRC-predisposing syndrome, accounting for about 3% of all CRC cases (Popat et al., 2005). LS is associated with mutations of DNA mismatch repair (MMR) genes such as MLH1, MSH2, MSH6, PMS2, and EPCAM (Ligtenberg et al., 2009; Lynch et al., 2009), which can trigger a high frequency of replication errors in both microsatellite regions and repetitive sequences in the coding regions of various cancer-related genes. Immunohistochemistry (IHC) tests followed by genetic analysis of these mutations play a significant role in diagnosis, treatment determination, and therapeutic response prediction of LS (Lynch et al., 2009; Alex et al., 2017; Ryan et al., 2017). Here, we report substitution of one base-pair in exon 1 of MLH3 (c.1397C>A) and a frameshift mutation in exon 19 of MLH1 (c.2250_2251ins AA) in a 43-year-old Chinese male with an LS pedigree.

Case of D-Variant from a Frameshift Mutation RHD 711delC / 대한수혈학회지

D antigens are clinically significant, and routine tests on the D antigen requires the inclusion of weak D testing, which is performed using indirect antihuman immunoglobulin methods. On the other hand, exact typing of the D type of an individual can be done more precisely with RHD genotyping, which is a useful tool in cases where the RHD gene is intact. The majority of weak-D or partial-D cases are from single nucleotide changes or hybridization of RHD and RHCE genes. Nevertheless, frameshift mutations can also result in weak or partial-D. The characteristics of a frameshift mutation is typically a change in protein product after a problematic mutation and early termination of transcription, leading into truncated protein products. This paper reports a D-variant case with RHD 711delC along with a review of the relevant literature. In addition, the results of software analysis are reported.

Waardenburg Syndrome Type IV De Novo SOX10 Variant Causing Chronic Intestinal Pseudo-Obstruction / 대한소아소화기영양학회지

Waardenburg syndrome (WS) type IV is characterized by pigmentary abnormalities, deafness and Hirschsprung's disease. This syndrome can be triggered by dysregulation of the SOX10 gene, which belongs to the SOX (SRY-related high-mobility group-box) family of genes. We discuss the first known case of a SOX10 frameshift mutation variant defined as c.895delC causing WS type IV without Hirschsprung's disease. This female patient of unrelated Kuwaiti parents, who tested negative for cystic fibrosis and Hirschsprung's disease, was born with meconium ileus and malrotation and had multiple surgical complications likely due to chronic intestinal pseudo-obstruction. These complications included small intestinal necrosis requiring resection, development of a spontaneous fistula between the duodenum and jejunum after being left in discontinuity, and short gut syndrome. This case and previously reported cases demonstrate that SOX10 gene sequencing is a consideration in WS patients without aganglionosis but with intestinal dysfunction.

A novel frameshift mutation of PRRT2 in a family with infantile convulsions and choreoathetosis syndrome: c.640delinsCC (p.Ala214ProfsTer11)

The infantile convulsions and choreoathetosis (ICCA) syndrome is defined when two overlapping clinical features of benign familial infantile epilepsy (BFIE) and paroxysmal kinesigenic dyskinesia (PKD) are present in an individual or a family. Since the gene encoding proline-rich transmembrane protein 2 (PRRT2) was first identified in Han Chinese families with PKD, mutations of PRRT2 have additionally been reported in patients with BFIE and ICCA. We attempted to identify the genetic etiology in an ICCA family where the proband, her elder sister, and a maternal male cousin had BFIE, and her mother had PKD. Whole-exome sequencing performed in the proband and her sister and mother identified a novel pathogenic mutation of PRRT2 (c.640delinsCC; p.Ala214ProfsTer11), which was verified by Sanger sequencing. This frameshift PRRT2 mutation located near the genetic hot spot of base 649_650 results in the premature termination of the protein, as do most previously reported mutations in BFIE, ICCA, and PKD.

Genetic diagnosis of a patient with long-time misdiagnosis of epilepsy / 中华医学遗传学杂志

OBJECTIVE@#To identify pathogenic mutation of TSC1 and TSC2 genes in a patient with long-time misdiagnosis of epilepsy.@*METHODS@#Peripheral blood samples and clinical data of the patient and her 2 parents were collected. Potential mutation of TSC1 and TSC2 genes were detected by direct sequencing.@*RESULTS@#The patient had frequent episodes of epilepsy in addition with Shagreen patches for 10 years. A frame-shifting mutation c.2509_2512delAACA was detected in exon 20 of the TSC1 gene. This same mutation was not found in her unaffected parents.@*CONCLUSION@#The recurrent frame-shifting mutation c.2509_2512delAACA (p.Asn837ValfsX11) of the TSC1 gene probably underlies the disease in this patient.

Tricho-rhino-phalangeal syndrome due to a novel frameshift variation of the TRPS1 gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology of a pedigree affected with tricho-rhino-phalangeal syndrome.@*METHODS@#Next-generation sequencing (NGS) using a gene panel for hereditary osteopathies was carried out for the proband. Suspected mutation was validated in the proband and her parents by Sanger sequencing.@*RESULTS@#A heterozygous frameshift variation c.1995dupA (p.Gly666Argfs*20) of the TRPS1 gene was detected in the proband but not in her parents.@*CONCLUSION@#The novel c.1995dupA (p.Gly666Argfs*20) mutation of the TRPS1 gene probably underlies the disease in the proband.

Clinical features and TRPM6 mutations of an infant with hypomagnesemia with secondary hypocalcemia / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical features and mutations of the TRPM6 gene in an infant featuring hypomagnesemia and secondary hypocalcemia.@*METHODS@#Clinical data of the patient was collected. Genomic DNA was extracted from peripheral blood samples from the patient and her parents. Targeted exome sequencing was carried out to screen the potential mutations. Suspected mutations were verified by Sanger sequencing.@*RESULTS@#A novel homozygous c.5538delA (p.Q1846Qfs*2) mutation in the TRPM6 gene was identified in the proband, for which both of her parents were heterozygous carriers.@*CONCLUSION@#The homozygous frameshift mutation of TRPM6 gene (c.5538delA) probably underlies the disease in the proband. The finding has expanded the mutation spectrum of TRPM6 gene.

Identification of pathogenic variations in two Chinese pedigrees affected with hereditary multiple exostosis / 中华医学遗传学杂志

OBJECTIVE@#To identify pathogenic variations of EXT1 and EXT2 genes in two Chinese pedigrees affected with hereditary multiple exostosis (HME).@*METHODS@#Genomic DNA was extracted from peripheral blood samples using a phenol-chloroform method. PCR and Sanger sequencing was conducted to amplify the exons and the flanking intronic regions of the EXT1 and EXT2 genes.@*RESULTS@#DNA sequencing has revealed a heterozygous missense variation c.812A>G (p.Tyr271Cys) in the exon 1 of EXT1 in pedigree 1, and a heterozygous frameshift variation c.1431dup (p.Ser478Leufs*43) in the exon 6 of EXT1 in the proband from pedigree 2. Both variations have co-segregated with the disease phenotype, which was also consistent with previous report.@*CONCLUSION@#Two heterozygous pathogenic variations underlying HME have been identified. The result has facilitated genetic counseling and prenatal diagnosis for the affected pedigrees.

A frameshift mutation in the TRPS1 gene showing a mild phenotype of trichorhinophalangeal syndrome type 1

Tricho-rhino-phalangeal syndrome (TRPS) is a hereditary disorder characterized by craniofacial and skeletal abnormalities. A mutation of the TRPS1 gene leads to TRPS type I or type III. A 20-year-old male patient visited our neurologic department with chronic fatigue. He presented with short stature, sparse hair, pear-shaped nose, and brachydactyly. Radiologic study showed short metacarpals, metatarsals with cone-shaped epiphyses, hypoplastic femur and hip joint. Panel sequencing for OMIM (Online Mendelian Inheritance in Man) listed genes revealed a de novo heterozygous frameshift mutation of c.1801_1802delGA (p.Arg601Lysfs*3) of exon 4 of the TRPS1 gene. The diagnosis of TRPS can be challenging due to the rarity and variable phenotype of the disease, clinicians should be aware of its characteristic clinical features that will lead a higher rate of diagnosis.