A Chinese homozygote of familial hypercholesterolemia: identification of a novel C263R mutation in the LDL receptor gene

Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by mutations in the low-density lipoprotein receptor (LDLR) gene; it is characterized by a high concentration of LDL, which frequently gives rise to tendon xanthomas and premature coronary artery disease (CAD). Individuals with heterozygous FH in China often exhibit a milder phenotype than those in other countries. The diagnosis of heterozygous FH relies on the clinical phenotype and this does not always permit unequivocal diagnosis of the disease. In the course of investigation of FH in a Chinese population sample, we found a family whose proband showed a markedly raised concentration of LDL cholesterol in plasma, and the presence of skin and tendon xanthomata. We used single-strand conformation polymorphism (SSCP) analysis to screen all the 18 exons and the exon-intron boundaries of the LDLR gene. One novel homozygous mutation, replacing T by C at nucleotide 850 in exon 6 was identified. This change substituted cysteine for arginine at codon 263 (C263R) of the LDLR. By means of mutant allele-specific amplification, we unequivocally diagnosed six heterozygotes with this novel mutation in the proband's family. Received: October 30, 2000 / Accepted: December 18, 2000     

FLT3 and its role in the pathogenesis of acute myeloid leukaemia

FLT3, a tyrosine kinase receptor class III (RTK), and its ligand (FL) are important for normal haematopoiesis and the development of the immune system. Recently, internal tandem duplications (FLT3 ITDs) in exons 14 and/or 15 that lead to constitutive receptor activation, have been described in 20-25% of adults with acute myeloid leukaemia (AML). The FLT ITD mutations, which are thought to disrupt a repressor sequence in the juxta-membrane region, confer a poor prognosis in AML, especially in patients under the age of 60 years. Furthermore, FLT3 "activating loop" mutations involving exon 20 have been reported in 7% of AML cases, making FLT3 the most commonly mutated gene in AML. FLT3, therefore, is a potentially important molecular target for AML therapy and already phase I clinical trials have been initiated.     

Can EGFR mutations in plasma or serum be predictive markers of non-small-cell lung cancer? A meta-analysis

BackgroundThe detection of epidermal growth factor receptor (EGFR) mutations in plasma or serum has previously been reported to be feasible for non-small-cell lung cancer (NSCLC). However, not all results indicate a consistency between EGFR mutation status in the plasma or serum and that in tissues.MethodsA meta-analysis was performed to evaluate the overall accuracy of EGFR mutation detection in plasma or serum. Publications up to December 2014 were searched for using the PubMed, Embase and Web of Science databases. Sensitivity, specificity and other accuracy measures were pooled using the bivariate mixed-effects regression model.ResultsTwenty-six studies were included in this meta-analysis. The pooled specificity, sensitivity, positive and negative likelihood ratios, and diagnostic odds ratios were 0.97 (95% confidence interval (CI): 0.93–0.99), 0.65 (95% CI: 0.54–0.74), 24.9 (95% CI: 9.2–67.2), 0.36 (95% CI: 0.27–0.48), and 69 (95% CI: 24–202), respectively. The summary receiver operating characteristic curve was 0.89 (95% CI: 0.86–0.91).ConclusionsThe detection of EGFR mutations in plasma or serum is a noninvasive method to confirm EGFR mutation status in patients with NSCLC. However, more work is necessary to identify which method can raise the sensitivity of EGFR mutation detection.     

Molecular,biochemical, and clinical characterization of mitochondrial acetoacetyl-coenzyme A thiolase deficiency in two further patients

The molecular basis of mitochondrial acetoacetyl-CoA thiolase (T2) deficiency was studied in two patients (GK11 and GK16). Fibroblasts from each patient had detectable immunoreactive T2 polypeptide (CRM). In pulse-chase experiments, fibroblasts from GK11 had two types of CRM: one (type I CRM) disappeared after a 24-hr chase and migrated more slowly than that of the normal control; the other (type II CRM) was detected with a small amount even after a 72-hr chase and had normalelectrophoretic mobility. GK16's fibroblasts had a CRM (type III) which was also detectable even after a 72-hr chase and showed a slower mobility than type I CRM. By analyzing amplified cDNA and genomic fragments, we showed that both patients are genetic compounds; GK11 for the mutations N158D and T297M, and GK16 for the mutations A301P and IVS8 ( + 1). Expression analyses confirmed that mutant T2 subunits with N158D, T297M, and A301P correspond to type I, II, and III CRM, respectively. Among them, only the mutant T2 polypeptide with T297M appeared to have a detectable residual activity, in spite of its instability. Cotransfection of two cDNAs containing N158D and T297M suggested that heterotetramer formation reduces residual activity in GK11 cells.© 1995 wiley-Liss, Inc.     

BRCA1 mutations and phenotype

More than 100 mutations have been described for the breast-cancer-susceptibility geneBRCA1. The paper describes phenotypical aspects of three selected mutations located at the beginning, in the middle, and at the end of the gene. A remarkable decrease of the age of diagnosis of the mammary carcinoma is observed with increasing length of the putative gene product, combined with greater severity of the disease.     

Hb Lusaka [α131(H14)Ser→Phe (α1)]: A New Variant Found in a Woman Heterozygous for Hb S [β6(A3)Glu→Val]

The present study attempts to delineate the spectrum of β‐thalassemia (thal) mutations in Tunisia by studying a large population from different parts of the country. A total of 285 unrelated subjects, 190 of whom had β‐thal major, 72 with Hb S/β‐thal, one with Hb C/β‐thal, one with Hb O‐Arab/β‐thal and 21 β‐thal carriers, were studied. The molecular defects were detected in 97.7% of the β‐thalassemic chromosomes (n?=?475). Nineteen different β‐thalassemic alleles were identified. Two mutations, namely codon 39 (C→T) and IVS‐I‐110 (G→A) accounted for 70.0% of the studied chromosomes, followed by IVS‐I‐1 (G→A) (4.5%). Five other mutations, frameshift codon (FSC) 44 (–C), codon 30 (G→C), IVS‐I‐2 (T→G), IVS‐II‐745 (C→G), and FSC 6 (–A), are not uncommon in this population, while the remaining 11 mutations, IVS‐I‐5 (G→A), ??30 (T→A), codons 25/26 (+?T), IVS‐I‐6 (T→C), FSC 5 (–CT), IVS‐II‐848 (C→A), FSC 8 (–AA), –87 (C→G), IVS‐I‐5 (G→C), IVS‐II‐1 (G→A) and IVS‐II‐849 (A→C) are quite rare; four of these have not been previously reported in the Tunisian population. Potential origin and spread of these mutations to Tunisia are also discussed.     

Validación de una nueva estrategia para la identificación de variantes de SARS-CoV-2 mediante secuenciación del gen espiga por Sanger

IntroductionThe emergence of multiple variants of SARS-CoV-2 during the COVID-19 pandemic is of great world concern. Until now, their analysis has mainly focused on next-generation sequencing. However, this technique is expensive and requires sophisticated equipment, long processing times, and highly qualified technical personnel with experience in bioinformatics. To contribute to the analysis of variants of interest and variants of concern, increase the diagnostic capacity, and process samples to carry out genomic surveillance, we propose a quick and easy methodology to apply, based on Sanger sequencing of 3 gene fragments that code for protein spike.MethodsFifteen positive samples for SARS-CoV-2 with a cycle threshold below 25 were sequenced by Sanger and next-generation sequencing methodologies. The data obtained were analyzed on the Nextstrain and PANGO Lineages platforms.ResultsBoth methodologies allowed the identification of the variants of interest reported by the WHO. Two samples were identified as Alpha, 3 Gamma, one Delta, 3 Mu, one Omicron, and 5 strains were close to the initial Wuhan-Hu-1 virus isolate. According to in silico analysis, key mutations can also be detected to identify and classify other variants not evaluated in the study.ConclusionThe different SARS-CoV-2 lineages of interest and concern are classified quickly, agilely, and reliably with the Sanger sequencing methodology.