The distal arthrogryposis-linked p.R63C variant promotes the stability and nuclear accumulation of TNNT3.

BACKGROUND: Distal arthrogryposis (DA) is comprised of a group of rare developmental disorders in muscle, characterized by multiple congenital contractures of the distal limbs. Fast skeletal muscle troponin-T (TNNT3) protein is abundantly expressed in skeletal muscle and plays an important role in DA. Missense variants in TNNT3 are associated with DA, but few studies have fully clarified its pathogenic role. METHODS: Sanger sequencing was performed in three generation of a Chinese family with DA. To determine how the p.R63C variant contributed to DA, we identified a variant in TNNT3 (NM_006757.4): c.187C>T (p.R63C). And then we investigated the effects of the arginine to cysteine substitution on the distribution pattern and the half-life of TNNT3 protein. RESULTS: The protein levels of TNNT3 in affected family members were 0.8-fold higher than that without the disorder. TNNT3 protein could be degraded by the ubiquitin-proteasome complex, and the p.R63C variant did not change TNNT3 nuclear localization, but significantly prolonged its half-life from 2.5 to 7 h, to promote its accumulation in the nucleus. CONCLUSION: The p.R63C variant increased the stability of TNNT3 and promoted nuclear accumulation, which suggested its role in DA.

[Analysis of SACS mutation in a family affected with autosomal recessive spastic ataxia of Charlevoix-Saguenay].

OBJECTIVE: To carry out mutation analysis for a Chinese family affected with autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). METHODS: Whole exome sequencing (WES) was used to screen potential mutations within genomic DNA extracted from the proband. Suspected mutation was validated by combining clinical data and results of Sanger sequencing. RESULTS: A homozygous deletional mutation c.3665_3675delGTGCTGTCTTA (p.S1222fs) was found in the proband, for which her parents were both heterozygous carriers. CONCLUSION: WES is capable of detecting mutation underlying this disorder and facilitating genetic counseling and prenatal diagnosis for the affected family. A novel pathogenic mutation of the SACS gene was discovered.

[Variant analysis for a pedigree affected with limb-girdle muscular dystrophy type 2D].

OBJECTIVE: To analyze variant of SGCA gene in a Chinese pedigree affected with limb-girdle muscular dystrophy type 2D with whole exome sequencing (WGS). METHODS: Multiplex ligation-dependent probe amplification (MLPA) was employed to detect large fragment deletion or duplication of the DMD gene. FastTargetTM next generation sequencing was used to detect variants of the DMD gene, and the result was verified by Sanger sequencing. After excluding the diagnosis of DMD for the proband, WGS was applied to test the proband and his parents. Suspected pathogenic variants were validated by Sanger sequencing. RESULTS: No variant, deletion or duplication of the DMD gene was detected. Whole exome sequencing showed that the proband has carried compound heterozygous missense variants c.409G>A (p.Glu137Lys) and c.409G>C (p.Glu137Gln) in exon 5 of the SGCA gene, which were respectively inherited from his mother and father. Neither variant was found in DNA derived from the cord blood sample. CONCLUSION: The c.409G>A (p.Glu137Lys) and c.409G>C (p.Glu137Gln) compound heterozygous missense variants probably underlie the disease in the proband. Above finding has facilitated genetic counseling and prenatal diagnosis for the family.

[Whole exome sequencing analysis for a Chinese pedigree affected with X-Linked intellectual disability].

OBJECTIVE: To explore the clinical features and genetic mutation in a family affected with non-syndrome X-linked intellectual disability (NS-XLID) using whole exome sequencing (WES). METHODS: Multiplex ligation-dependent probe amplification (MLPA) was applied to screen potential mutations of Fragile X syndrome (FXS). Whole exome sequencing (WES) and Sanger sequencing were screen for pathological mutations. RESULTS: FXS was excluded by MLPA analysis. WES has discovered in the proband an ARX gene mutation c.88G>T, which was confirmed by Sanger sequencing. Combining his clinical phenotype with information from the OMIM database, it was inferred that the ARX mutation probably underlies the NS-XLID in the proband. The same mutation was found in his mother and two uncles but not in his father and sister. CONCLUSION: WES is capable of revealing the mutation underlying NS-XLID and can facilitate genetic counseling for the affected families.

[Mutation analysis for a Chinese family affected with Escobar syndrome by whole exome sequencing].

OBJECTIVE: To carry out mutation analysis for a Chinese family affected with Escobar syndrome. METHODS: Whole exome sequencing (WES) was employed to detect potential mutation in the proband. Suspected mutations were validated by combining clinical data and result of Sanger sequencing. RESULTS: A homozygous missense mutation c.715C>T (p.R239C) was detected in the proband and his brother who was also affected. The parents and the daughters of the proband carried the heterozygous mutation c.715C>T, while other family members did not carry the mutation. CONCLUSION: Escobar syndrome is a rare genetic disorder. WES is able to discover genetic mutation underlying this disorder and facilitate genetic counseling and prenatal diagnosis for the affected family.

[Mutational analysis and prenatal diagnosis in a family affected with hypophosphatemic rickets].

OBJECTIVE: To explore the clinical characteristics and genetic mutation in a family affected with hypophosphatemic rickets. METHODS: Whole exome sequencing (WES) was used to screen potential mutations in genomic DNA extracted from peripheral venous blood sample from the proband. Suspected mutation was confirmed with Sanger sequencing. Amniotic fluid was sampled from the proband for prenatal diagnosis. Potential maternal contamination was excluded by analysis of short tandem repeat (STR) markers. RESULTS: WES has identified a heterozygous c.2058_2059insAGTT (p.L686fs) mutation of the PHEX gene in the proband, which was confirmed by Sanger sequencing in other affected individuals from the family. The mutation was detected in the amniotic fluid sample from the fetus but not among healthy members from the family. CONCLUSION: Identification of the PHEX mutation by WES has facilitated genetic counseling and prenatal diagnosis for the family affected with hypophosphatemic rickets.

Predictive Modelling of Overall Survival in Adult Patients with Primary Diffuse Large B-cell Lymphoma of the Breast Using the Surveillance, Epidemiology, and End Results (SEER) Database.

OBJECTIVE: We aimed to identify critical clinical features to develop an accurate webbased prediction model for estimating the overall survival (OS) of primary breast diffuse large Bcell lymphoma (PB-DLBCL) adult patients. METHODS: We first included all PB-DLBCL cases with available covariates retrieved from the Surveillance, Epidemiology, and End Results database. We sequentially performed univariate and multivariate Cox regression approaches to identify the predictors independently associated with prognosis, and all the predictors that passed these tests were then constructed to build a nomogram for predicting 3-, 5-, and 10-year survival rates of patients. The C-index and the receiver operating characteristic curve (ROC) were used to evaluate the prediction discrimination, and the calibration curve was applied to estimate the calibration. RESULTS: A total of PB-DLBCL adult patients were included (median age was 69 with the interquartile range [IQR] of 57-79 years), of which 466 (70%) were randomly allocated to the development cohort, and the remaining cases were collected for validation. Using three identified independent predictors (i.e., age, stage, and radiation), an accurate nomogram for predicting OS was developed and validated. The C-indices of our nomogram were both relatively acceptable, with 0.74 (95% CI: 0.71-0.78) and 0.72 (95% CI: 0.70-0.75) for the development and validation cohorts, respectively. The calibration curves also accurately predicted the prognosis of PB-DLBCL in all cases. In addition, ROC curves showed our nomogram to possess superior predictive ability compared to any single variable. To visually present this prediction model, a convenient webbased tool was implemented based on our prognostic nomogram. CONCLUSION: For patients with PB-DLBCL, a more convenient and accurate web-based prediction model was developed and validated, which showed relatively good performances in both discrimination and calibration during model development and validation. External evaluation and validation are warranted by further independent studies.

Mutation analysis and prenatal diagnosis of a family with congenital contractural arachnodactyly.

BACKGROUND: Congenital contractural arachnodactyly (CCA) is a rare autosomal dominant condition caused by mutations in the fibrillin 2 gene (FBN2). The primary clinical symptoms of CCA include multiple flexion contractures, arachnodactyly, dolichostenomelia, scoliosis, abnormal pinnae, muscular hypoplasia, and crumpled ears. METHODS: We used whole-exome sequencing technology to examine an arthrogryposis multiplex congenita and used Sanger sequencing technology to genetically confirm its family. RESULTS: FBN2 c.3344A>T(p.D1115V) was identified in this family with CCA in a pedigree. Prenatal diagnosis and counseling were carried out simultaneously to avoid the birth of the sick fetus. CONCLUSION: The study is on FBN2 variant in CCA, which potentially having implications for genetic counseling and clinical management, our study may provide new insights into the cause and diagnosis of CCA.