Characterisation of a new familial amyotrophic lateral sclerosis

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Spectrum of BCR-ABL1 kinase domain mutations: A cohort study from Saudi Arabia

Background: The BCR-ABL1 tyrosine kinase domain mutation constitutes a major cause of resistance to the tyrosine kinase inhibitors in patients with chronic myeloid leukemia (CML). In this retrospective study, we assessed the ABL kinase domain mutation in 123 patients (61 females and 62 males) aged 10–79 years (median age of 50 years). These patients were referred to our clinics at King Faisal Specialist Hospital and Research Center (General Organization), Riyadh, Kingdom of Saudi Arabia during period (2011–2014). These patients had Philadelphia-positive CML displaying either failure to tyrosine kinase inhibitor (TKI) or suboptimal response with increased BCR-ABL1 levels through serial monitoring by using quantitative Real time PCR. Methods: The mutation analysis was performed on RNA extracted from Peripheral blood samples after the amplification of the BCR-ABL1 transcript by nested PCR followed by direct sequencing of the BCR-ABL1 kinase domain including the residues (243–487). Results: Of 123 patients, 119 adults and four pediatrics were analyzed. From the total, 25 (20%) were tested positive for 11 different mutations in the ABL1 kinase domain (11 patients with T315I, 3 with Y253H, 2 with E255K, 2 F317L, and 1 patient having each of the following mutations: F359I, E355G, V299L, L248V, L298, M244V, and Y326H). The duration from the diagnosis to mutation detection ranged between 3 and 144 months with a median duration of four years. Conclusion: Despite the retrospective nature of the study and relatively small sample size of a single center analysis, the mutation frequency is in line with similar reported studies from other parts of the world

Cytogenetics and molecular markers of acute myeloid leukemia from a tertiary care center in Saudi Arabia

Background/Purpose: Acute myeloid leukemia (AML) is a phenotypically and genetically heterogeneous disease. This heterogeneity is attributed to alterations in genetic bases. AML classification based on these abnormalities is essential for accurate diagnosis, risk stratification, prognostic value, monitoring of minimal residual disease, and developing targeted therapies. This study evaluates frequency of each karyotype and molecular abnormality at our institution with comparison to other international studies. Materials and Methods: We reviewed 100 bone marrow samples, which represent all AML diagnosed cases at our hospital from 2012 to 2014 by conventional karyotyping, specific AML–FISH panel, and variety of AML-specific mutations using Sanger sequencing. Results: Out of 100 AML patients investigated with median age of 29 years, 98 were successfully karyotyped, and 64% of cases had an abnormality. In addition, all 100 AML–FISH panel and molecular studies were informative with an abnormality reaching 50 and 45%, respectively. Conventional and molecular cytogenetic studies revealed trisomy 8 (15%), t(8;21) in 12%, trisomy 21(8%), inv(16) in 7%, t(15;17) in 6%, 11q rearrangements (6%), and inv(3) in 2%. The mutational analysis showed nucleophosmin 1 (12%), FMS-like tyrosine kinase-3–internal tandem duplication (9%), IDH2 (7%), IDH1 (6%), WT1 (5%), DNMT3A (4%), CEBPA (4%), and c-KIT (3%). Conclusion: The incidence of most mutational analysis is lower, whereas abnormal karyotype showed almost similar frequency when compared to different international centers. This is the first cytogenetic data from Saudi Arabia for AML, including all these genetic mutations. Therefore, a multicenter collaboration and comprehensive study is recommended to confirm these findings

A New Familial Amyotrophic Lateral Sclerosis Locus on Chromosome 16q12.1-16q12.2

Familial amyotrophic lateral sclerosis (FALS) affects 5%–10% of cases of amyotrophic lateral sclerosis (ALS) and is inherited as an autosomal dominant condition with incomplete penetrance. One-fifth of these cases of FALS are associated with mutations in copper/zinc-dependent superoxide dismutase (SOD1), but the gene defect in the remaining 80% of familial cases is, as yet, unknown. We have carried out a preliminary genome screen, using a U.K. resource of families lacking SOD1 mutations, to identify other potential disease loci and have identified a putative locus on chromosome 16q12.1-q12.2. The region associated with disease was further refined in the major family that contributed to this result and was localized to D16S409–D16S3032, a 14.74-cM genetic interval that corresponds to a physical distance of 6.6 Mb, which coincides with a region independently identified by two further research groups in the United States and the United Kingdom

4. Identification of a novel nonsense variant C.1332DUP, P. (D445*) in the LDLR gene that causes familial hypercholesterolemia

Basic Science Research. Presentation type: Digital Poster. Introduction: Familial hypercholesterolemia (FH) is an autosomal dominant disease predominantly caused by a mutation in the low-density lipoprotein receptor (LDLR) gene. Here, we describe two severely affected FH patients from the same Saudi family, who were resistant to statin therapy and were managed on an apheresis program. Methodology: Two proband samples were collected from the patients. Direct sequencing of the LDLR gene was performed by using the Sanger sequencing method. Results: We identified a novel duplication variant c.1332dup, p. (D445*) at exon 9 and a known silent variant c.1413A>G, p. (=), rs5930, NM_001195798.1 at exon 10 of the LDLR gene in both patients. Both probands were homozygous for the mutation, which is located in the EGF-precursor homology domain of the LDLR protein, and show severe FH phenotype. Conclusion: The duplication variant results in the production of a defective LDL receptor containing the p. (D445*) variant. This variant results in a premature stop codon at position 445 in exon 9 of the LDLR gene, which results in truncation of the protein. The segregation pattern of the variant is consistent with the lipid profile, suggesting a more severe FH phenotype when the variant is in the homozygous state. Finding of this study could be very useful in developing critical genetic screen for potential FH patients. In addition, these data contribute to the understanding of the molecular basis of FH in Saudis

1. Founder mutation identified in the LDLR gene causing familial hypercholesterolemia associated with increased risk of coronary heart disease

Basic science research. Presentation Type: Oral presentation. Introduction: Coronary artery diseases (CAD) inflict heavy economical and social cost on most populations including Saudi’s and contribute significantly to their morbidity and mortality rates. Familial hypercholesterolemia (FH) is hereditary in an autosomal dominant disease and is a major risk factor for the development of CAD. FH is predominantly caused by variants in the low-density lipoprotein (LDL) receptor gene (LDLR). Methodology: More than 140 FH samples including 44 probands were collected from 17 unrelated Saudi families who live in the central, northern, western and eastern regions of Saudi Arabia. Patient samples were screened using Next-generation sequencing (NGS) and Capillary sequencing. We described the genetic analysis of severely affected homozygous FH patients who were mostly resistant to statin therapy and were managed on an apheresis program. Results: We identified a common frameshift mutation p. (G676Afs*33) in exon 14 of the LDLR gene in 17 probands and their first-degree blood relatives in apparently unrelated Saudi families. This founder mutation was found in about 40% Saudi FH population. We also describe a three dimensional homology model of the LDL receptor protein (LDLR) structure and examine the consequence of the frameshift mutation p. (G676Afs*33), as this could affect the LDLR structure in a region involved in dimer formation, and protein stability. Conclusion: This finding of a recurrent mutation causing FH in the Saudi population could serve to develop a rapid genetic screening procedure for FH, and the 3D-structure analysis of the mutant LDLR, may provide tools to develop a mechanistic model of the LDLR function