Codon, Nonsense ; Epilepsy ; genetics ; Humans ; KCNQ2 Potassium Channel ; genetics

Objective: To analyze the phenotype and genotype of two pedigrees with inherited fibrinogen (Fg) deficiency caused by two heterozygous mutations. We also preliminarily probed the molecular pathogenesis. Methods: The prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and plasma fibrinogen activity (Fg∶C) of all family members (nine people across three generations and three people across two generations) were measured by the clotting method. Fibrinogen antigen (Fg:Ag) was measured by immunoturbidimetry. Direct DNA sequencing was performed to analyze all exons, flanking sequences, and mutated sites of FGA, FGB, and FGG for all members. Thrombin-catalyzed fibrinogen polymerization was performed. ClustalX 2.1 software was used to analyze the conservatism of the mutated sites. MutationTaster, PolyPhen-2, PROVEAN, SIFT, and LRT online bioinformatics software were applied to predict pathogenicity. Swiss PDB Viewer 4.0.1 was used to analyze the changes in protein spatial structure and molecular forces before and after mutation. Results: The Fg∶C of two probands decreased (1.28 g/L and 0.98 g/L, respectively). The Fg∶Ag of proband 1 was in the normal range of 2.20 g/L, while it was decreased to 1.01 g/L in proband 2. Through genetic analysis, we identified a heterozygous missense mutation (c.293C>A; p.BβAla98Asp) in exon 2 of proband 1 and a heterozygous nonsense mutation (c.1418C>G; p.BβSer473*) in exon 8 of proband 2. The conservatism analysis revealed that Ala98 and Ser473 presented different conservative states among homologous species. Online bioinformatics software predicted that p.BβAla98Asp and p.BβSer473* were pathogenic. Protein models demonstrated that the p.BβAla98Asp mutation influenced hydrogen bonds between amino acids, and the p.BβSer473* mutation resulted in protein truncation. Conclusion: The dysfibrinogenemia of proband 1 and the hypofibrinogenemia of proband 2 appeared to be related to the p.BβAla98Asp heterozygous missense mutation and the p.BβSer473* heterozygous nonsense mutation, respectively. This is the first ever report of these mutations.
Humans ; Afibrinogenemia/genetics* ; Codon, Nonsense ; Pedigree ; Phenotype ; Fibrinogen/genetics* ; Genotype

In the past few years, the bone field has witnessed great advances in genome-wide association studies (GWASs) of osteoporosis, with a number of promising genes identified. In particular, meta-analysis of GWASs, aimed at increasing the power of studies by combining the results from different study populations, have led to the identification of novel associations that would not otherwise have been identified in individual GWASs. Recently, the first whole genome sequencing study for osteoporosis and fractures was published, reporting a novel rare nonsense mutation. This review summarizes the important and representative findings published by December 2013. Comments are made on the notable findings and representative studies for their potential influence and implications on our present understanding of the genetics of osteoporosis. Potential limitations of GWASs and their meta-analyses are evaluated, with an emphasis on understanding the reasons for inconsistent results between different studies and clarification of misinterpretation of GWAS meta-analysis results. Implications and challenges of GWAS are also discussed, including the need for multi- and inter-disciplinary studies.
Codon, Nonsense ; Genetics ; Genome ; Genome-Wide Association Study* ; Osteoporosis*

Animals ; Codon, Nonsense ; Disease ; genetics ; Drosophila ; genetics ; metabolism ; Drosophila Proteins ; genetics ; Humans ; Pseudogenes ; Receptors, Odorant ; genetics

OBJECTIVETo analyze clinical symptoms and disease-causing mutations of corneodesmosin (CDSN) gene in a Chinese family affected with hypotrichosis simplex of the scalp and to establish a method for prenatal diagnosis.

METHODSFamily survey and clinical examinations were carried out to determine the inheritance pattern. Three patients and 7 unaffected relatives from the family, in addition with 100 unrelated healthy controls were recruited. Genomic DNA from peripheral blood leukocytes was extracted. Five pairs of primers were designed based on the CDSN gene sequence. Exons and flanking regions of the CDSN gene were amplified using polymerase chain reaction (PCR). Potential mutations were analyzed through direct sequencing and comparison by BLAST.

RESULTSThe type of alopecia of the family was diagnosed as hypotrichosis simplex of the scalp with an autosomal dominant inheritance pattern. A nonsense mutation (C717G) in cDNA sequence of the CDSN gene was identified in all three patients of the family, which resulted in a premature stop codon (Y239X). The same mutation was not found among healthy members of the family and 100 healthy controls.

CONCLUSIONA Chinese family was diagnosed with hypotrichosis simplex of the scalp, which was caused by a novel nonsense mutation (Y239X) in the CDSN gene.

Alopecia ; genetics ; China ; Codon, Nonsense ; Female ; Glycoproteins ; genetics ; Humans ; Hypotrichosis ; genetics ; Male ; Middle Aged ; Pedigree ; Scalp

BACKGROUNDBardet-Biedl syndrome (BBS) is a genetically heterogeneous disease, and information about BBS in Chinese populations is very limited. The purpose of the present study was to determine the genetic cause of BBS in a Chinese Han family.

METHODSClinical data were recorded for the 4-year-old female proband and the available family members. The proband was screened for mutation by Sanger sequencing for a total of 142 exons of the 12 BBS-causing genes (BBS1-BBS12). The variants detected in the proband were further confirmed in the other family members.

RESULTSWe identified a novel homozygous nonsense mutation (c.70A>T, p.K24X) in the BBS4 gene exon 2 in the proband. Such mutant allele was predicted to cause a premature truncation in the N-terminal of the BBS4 protein, and probably induced the nonsense-mediated decay of BBS4 messenger RNAs. The proband's parents and brother were heterozygous for the nonsense mutant allele. It was absent in 50 Chinese control subjects. An additional rare heterozygous missense single nucleotide polymorphism (SNP) named rs200718870 in BBS10 gene was also detected in the proband, her father and her brother. Some manifestations of the proband including atypical retinitis pigmentosa, choroidal sclerosis, high myopia, and early onset of obesity might be associated with this mutation in BBS4 gene. The proband's father also reported surgical removal of an extra finger during childhood.

CONCLUSIONSThe present study described a novel nonsense mutation in BBS4 gene in a Chinese family. This homozygous mutation was predicted to completely abolish the synthesis of the BBS4 protein. We also detected a rare heterozygous missense SNP in BBS10 gene in the family, but did not find sufficient evidence to support the triallelic inheritance.

Bardet-Biedl Syndrome ; genetics ; Child, Preschool ; Codon, Nonsense ; genetics ; Female ; Humans ; Proteins ; genetics

OBJECTIVE: To investigate the relationship between the type of FⅧgene mutation and the development of FⅧ inhibitors in patients with severe haemophilia A (HA). METHODS: The medical records of 172 patients with severe hemophilia A from January 2009 to September 2020 were reviewed. The types of FⅧgene mutations and the production of factor Ⅷ inhibitors were collected and divided into high-risk mutation group ( intron 1 inversions, large deletions, nonsense mutations), low-risk mutation group (missense mutations, small deletions and insertions, splice site mutations) and intron 22 inversions group. The correlation of FⅧgenotype and the production of FⅧ inhibitors in patients with HA were analyzed. RESULTS: Among 172 patients with severe HA, 21 cases(12.21%) developed FⅧ inhibitors. The cumulative incidence of FⅧ inhibitor development was 32%(10/31) in high risk group (75% patients with large deletions, 43% patients with intron 1 inversions, 20% patients with nonsense mutations) and 5%(2/43) in low risk group(6% patients with missense mutations, 5% patients with small deletions or insertions and 0% patient with a splice site mutation) and 9%(9/98) in intron 22 inversions group. Compared with the risk of FⅧ inhibitor development in intron 22 inversions group, the risk of FⅧ inhibitor development in high risk group was higher (OR＝4.7, 95% CI： 1.7-13.0), the risk of FⅧ inhibitor development in low risk group was equal (OR＝0.5, 95% CI： 0.1-2.3). Compared with the risk of inhibitor development in low risk group, the risk of FⅧ inhibitor development in high risk group was higher (OR＝9.8, 95% CI： 2.0-48.7). CONCLUSION Gene mutations of patients with severe HA in high-risk group which include intron 1 inversions, large deletions, nonsense mutations are a risk factor for FⅧ inhibitor production.
Codon, Nonsense ; DNA Mutational Analysis ; Factor VIII/genetics* ; Hemophilia A/genetics* ; Humans ; Introns ; Mutation

OBJECTIVE: To explore the genetic basis for a pedigree affected with hereditary multiple osteochondroma (HMO). METHODS: Peripheral blood samples were collected from the proband and members of his pedigree with informed consent. Following extraction of genomic DNA, all coding exons and flanking intronic sequences (-10 bp) of the EXT1 and EXT2 genes were subjected to targeted capture and next generation sequencing (NGS). Suspected variant was verified by Sanger sequencing. RESULTS: A heterozygous nonsense variant (c.1911C>A) was found in exon 10 of the EXT1 gene in the proband and his affected father but not in a healthy sister and normal controls. The variant was classified as a pathogenic based on the guidelines of the American College of Medical Genetics and Genomics (PVS1+PM2+PP1). Bioinformatic analysis predicted that the c.1911C>A variant may be disease-causing via nonsense-mediated mRNA decay and anomalous splicing. CONCLUSION The c.1911C>A variant probably underlay the disease in this pedigree. Discovery of this variant enriched the variant spectrum of HMO.
Codon, Nonsense ; Exons/genetics* ; Exostoses, Multiple Hereditary/genetics* ; Heterozygote ; Humans ; Pedigree

OBJECTIVE: To analyze the clinical characteristics and ZBTB18 gene variant in a child with epilepsy and global developmental delay. METHODS: Clinical data and laboratory examination of the patient were reviewed. Whole exome sequencing (WES) was also carried out for the family trio. RESULTS: The main manifestations of the child included global developmental delay, short stature, epileptic seizures. EEG revealed frequent occurrence of sharp (slow) waves in the right central region during sleeping, with sharp waves occasionally seen in the frontal and right posterior temporal regions. Cranial MRI has shown no obvious abnormality. WES has identified a de novo pathogenic variant in the ZBTB18 gene [NM_205768.3: exon 2: c.1282_1283del (p.Phe428Leufs*72)]. Based on the guidelines from American College of Medical Genetics and Genomics (ACMG), the variant was classified as pathogenic (PS2+PVS1_Moderate+PM2_Supporting). Following treatment with levetiracetam and rehabilitation, the seizures have been controlled for nearly half a year, with improvement of the psychomotor and language development. So far 28 children have been discovered with ZBTB18 gene mutations, and there was a significant difference in the clinical phenotypes of motor retardation, language retardation and epilepsy between those harboring frameshift/nonsense mutations and missense mutations. CONCLUSION The c.1282_1283del (p.Phe428leufs *72) variant of the ZBTB18 probably underlay the autosomal dominant mental disorder type 22 in this child. Compared with missense mutations, frameshift/nonsense mutations may predispose more to motor retardation, delayed language development and epilepsy.
Codon, Nonsense ; Epilepsy/genetics* ; Humans ; Intellectual Disability/genetics* ; Mutation ; Whole Exome Sequencing

OBJECTIVETo detect the disease-causing mutation in a pedigree affected with autosomal dominant congenital cataract.

METHODSGenomic DNA was extracted and purified from peripheral blood samples from members of the pedigree and 100 healthy controls. Coding regions of 18 candidate genes were screened with PCR and Sanger sequencing. Identified mutations were verified among 100 healthy individuals to exclude single nucleotide polymorphisms.

RESULTSA heterozygous nonsense mutation c.471G>A of the CRYGD gene, which resulted in p.Trp157Term, was identified in all three patients. The same mutation was not found in the two normal individuals from the family and 100 healthy controls. The nonsense mutation was predicted to be "disease causing" by Mutation t@sting program.

CONCLUSIONThe nonsense mutation c.471G>A of the CRYGD gene probably underlies the congenital cataract in the pedigree.

Cataract ; etiology ; genetics ; Child ; Codon, Nonsense ; Humans ; Male ; Sequence Analysis, DNA ; gamma-Crystallins ; genetics