Identification of Genetic Mutations in TYR and OCA2 Genes in Congenital Families with Oculocutaneous Albinism (OCA)

2021 ◽  
Vol 15 (10) ◽  
pp. 2546-2549
Author(s):  
Muhammad Ikram Ullah ◽  
Muhammad Shakil ◽  
Adnan Riaz
Keyword(s):  
Molecular Basis ◽  
Sanger Sequencing ◽  
Mutation Detection ◽  
Genetic Mutation ◽  
Oculocutaneous Albinism ◽  
Genetic Mutations ◽  
Pakistani Families ◽  
Diagnostic Outcome ◽  
Panel Sequencing ◽  
Oca2 Gene

Aim: The objective of the present study was to recruit congenital families of oculocutaneous albinism (OCA) and mutations in TYR and OCA2 genes are identified, which is further expanding the mutation spectrum in this population. Methods: Two consanguineous families with OCA were recruited and whole blood was collected. Clinical examination was carried out to determine the visual acuity and related eye, skin and hair examinations. Genomic DNA was extracted by standard phenol-chloroform method. Targeted exome sequencing by TruSight one sequencing panel sequencing was carried out. Sanger sequencing was performed for mutation detection in tyrosinase (TYR) and the OCA2 genes and co-segregation in OCA families. Results: Clinically, the affected individuals of two OCA families showed clinical characteristics including white to pale skin, white or blonde hairs, irritant to light, nystagmus and reduced vision. DNA sequencing showed the genetic mutation of TYR and OCA2 genes in two OCA families. In family 1, the nucleotide variant (c.1255G>A; p.Gly419Arg) was detected inTYR gene, while in another family, the splice-site variant c.1045-15T>G was identified in OCA2. Conclusion: This study concluded that identification of TYR and OCA2 mutations in OCA disease are commonly associated with the population where the consanguinity is persistent. These findings expanded the molecular basis of oculocutaneous albinism in Pakistani families and established the mode of genetic counselling and for diagnostic outcome. Keywords: Consanguineous families; Oculocutaneous albinism (OCA); mutations; tyrosinase (TYR); OCA2 gene.

scholarly journals Increasing prevalence of resistance to second-line drugs among multidrug-resistant Mycobacterium tuberculosis isolates in Kuwait

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Noura M. Al-Mutairi ◽  
Suhail Ahmad ◽  
Eiman Mokaddas
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Mutation Detection ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Genetic Mutations ◽  
Second Line ◽  
Injectable Drugs ◽  
Mdr Tb ◽  
Phenotypic Susceptibility

AbstractMolecular methods detect genetic mutations associated with drug resistance. This study detected resistance-conferring mutations in gyrA/gyrB for fluoroquinolones and rrs/eis genes for second-line injectable drugs (SLIDs) among multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates in Kuwait. Fifty pansusceptible M. tuberculosis and 102 MDR-TB strains were tested. Phenotypic susceptibility testing was performed by MGIT 960 system using SIRE drug kit. GenoType MTBDRsl version 1 (gMTBDRslv1) and GenoType MTBDRsl version 2 (gMTBDRslv2) tests were used for mutation detection. Results were validated by PCR-sequencing of respective genes. Fingerprinting was performed by spoligotyping. No mutations were detected in pansusceptible isolates. gMTBDRslv1 detected gyrA mutations in 12 and rrs mutations in 8 MDR-TB isolates. gMTBDRsl2 additionally detected gyrB mutations in 2 and eis mutation in 1 isolate. Mutations in both gyrA/gyrB and rrs/eis were not detected. gMTBDRslv1 also detected ethambutol resistance-conferring embB mutations in 59 isolates. Although XDR-TB was not detected, frequency of resistance-conferring mutations for fluoroquinolones or SLIDs was significantly higher among isolates collected during 2013–2019 versus 2006–2012. Application of both tests is warranted for proper management of MDR-TB patients in Kuwait as gMTBDRslv2 detected resistance to fluoroquinolones and/or SLIDs in 3 additional isolates while gMTBDRslv1 additionally detected resistance to ethambutol in 58% of MDR-TB isolates.

scholarly journals Somatic mutation detection efficiency in EGFR: a comparison between High Resolution Melting Analysis and Sanger Sequencing

2020 ◽  
Author(s):  
Reenu Anne Joy ◽  
Sukrishna Kamalasanan Thelakkattusserry ◽  
Narendranath Vikkath ◽  
Renjitha Bhaskaran ◽  
Damodaran Vasudevan ◽  
...  
Keyword(s):  
High Resolution ◽  
Somatic Mutation ◽  
Sanger Sequencing ◽  
Mutation Detection ◽  
Detection Efficiency ◽  
Limit Of Detection ◽  
Tumor Tissues ◽  
Allele Specific ◽  
Somatic Mutation Detection ◽  
Allele Fraction

Abstract Background: High resolution melting curve analysis is a cost-effective rapid screening method for detection of somatic gene mutation. The performance characteristics of this technique has been explored previously, however, analytical parameters such as limit of detection of mutant allele fraction and total concentration of DNA, have not been addressed. The current study focuses on comparing the mutation detection efficiency of High-Resolution Melt Analysis (HRM) with Sanger Sequencing in somatic mutations of the EGFR gene in non-small cell lung cancer .Methods: The minor allele fraction of somatic mutations was titrated against total DNA concentration using Sanger sequencing and HRM to determine the limit of detection. The mutant and wildtype allele fractions were validated by multiplex allele-specific real-time PCR. Somatic mutation detection efficiency, for exons 19 & 21 of the EGFR gene, was compared in 116 formalin fixed paraffin embedded tumor tissues, after screening 275 tumor tissues by Sanger sequencing.Results: The limit of detection of minor allele fraction of exon 19 mutation was 1% with Sequencing, and 0.25% with HRM, whereas for exon 21 mutation, 0.25% MAF was detected using both methods. Multiplex allele-specific real-time PCR revealed that the wildtype DNA did not impede the amplification of mutant allele in mixed DNA assays. All mutation positive samples detected by Sanger sequencing, were also detected by HRM. About 28% cases in exon 19 and 40% in exon 21, detected as mutated in HRM, were not detected by sequencing. Overall, sensitivity and specificity of HRM were found to be 100% and 67% respectively, and the negative predictive value was 100%, while positive predictive value was 80%. Conclusion: The comparative series study suggests that HRM is a modest initial screening test for somatic mutation detection of EGFR, which must further be confirmed by Sanger sequencing. With the modification of annealing temperature of initial PCR, the limit of detection of Sanger sequencing can be improved.

scholarly journals Establishment and application of a multiplex genetic mutation-detection method of lung cancer based on MassARRAY platform

2016 ◽  
Vol 13 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Hong-Xia Tian ◽  
Hong-Xia Tian ◽  
Xu-Chao Zhang ◽  
Zhen Wang ◽  
Jian-Guang Chen ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Mutation Detection ◽  
Detection Method ◽  
Genetic Mutation

scholarly journals Targeted Next Generation Sequencing Identifies Novel Genetic Mutations in Patients with Waldenstrom's Macroglobulinemia/Lymphoplasmacytic Lymphoma or IgM-Monoclonal Gammopathies of Undetermined Significance

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2928-2928 ◽  
Author(s):  
Marzia Varettoni ◽  
Silvia Zibellini ◽  
Ettore Rizzo ◽  
Luca Malcovati ◽  
Virginia Valeria Ferretti ◽  
...  
Keyword(s):  
Sanger Sequencing ◽  
Somatic Mutations ◽  
Genetic Mutations ◽  
Wild Type ◽  
Targeted Next Generation Sequencing ◽  
Coefficient Of Concordance ◽  
Generation Sequencing ◽  
Myd88 L265p ◽  
Undetermined Significance

Abstract Background. TheMYD88 (L265P) somatic mutation is present in more than 90% of patients (pts) with Waldenström's Macroglobulinemia (WM)/lymphoplasmacitic lymphoma (LPL). The second most common mutations are nonsense (NS) or frameshift (FS) mutations in the CXCR4 gene, detectable in approximately 25-30% of WM pts by Sanger sequencing. Limited data are available about other genetic mutations in WM/LPL and its precursor condition IgM-monoclonal gammopathy of undetermined significance (IgM-MGUS). Pts and methods. Using targeted next generation sequencing (NGS), we evaluated the prevalence of somatic mutations of 11 genes selected on the basis of evidences available from the literature (MYD88, CXCR4, ARID1A, KMT2D, TP53, NOTCH2, PRDM1, CD79b, TRAF3,TNFAIP3, MYDBBP1A) in 119 pts, classified as WM/LPL (n=63) or IgM-MGUS (n=56) according to International Consensus Criteria. Median age of pts (67 males, 52 females) was 65 years (range: 38-82). Samples were collected at diagnosis (n=101), after diagnosis but before any treatment (n=9) or at progression after therapy (n=9). Paired tumor and germline DNA extracted respectively from CD19-selected and CD19-depleted bone marrow (BM) mononuclear cells was available in all pts. Mean resequencing depth across gene panel was 1009x. Only mutations tagged as oncogenic or possibly oncogenic based on information derived from the literature and on in silico prediction effect were considered in the analysis. For MYD88 (L265P) and CXCR4 mutations, results obtained with NGS were compared with those obtained respectively with allele-specific PCR (AS-PCR) and Sanger sequencing. Results. Overall, we found 151 mutations in 88 pts (74%). The median number of mutations was significantly higher in WM/LPL as compared with IgM-MGUS and in pts previously treated as compared with untreated ones (median 2 versus 1, P < 0.001 for both comparisons). MYD88 mutations were found in 80/119 pts (67%), with a median allele burden of 34.2% (range: 2.5-93.3%). The prevalence of MYD88 mutations was significantly higher in WM/LPL as compared with IgM-MGUS (86% versus 46%, P <0.001). MYD88 mutations other than classical L265P (n=76) were found in 4 pts and were represented by V217F (n=2), S219C (n=1), M232T (n=1). Fifteen pts who were MYD88 (L265P) wild-type by NGS were found to be mutated by AS-PCR (K coefficient of concordance between NGS and AS-PCR: 70%, P < 0.001). CXCR4 mutations were found in 19/119 pts (16%), with a median allele burden of 34% (range: 4.2-84%). The prevalence of CXCR4 mutations was significantly higher in WM/LPL as compared with IgM-MGUS (24% versus 7%, P < 0.02). The K coefficient of concordance between NGS and Sanger was 83% (P < 0.001), with 2 pts mutated only by NGS and 2 pts mutated only by Sanger. Somatic mutations were also found in KMT2D (formerly known as MLL2) (16% of pts), TP53 (8%), NOTCH2 (7%), PRDM1 (4%), ARID1A (3%), CD79b (2%), and TRAF3 (1%). No mutations were found in MYBBP1A and TNFAI3. Overall, the prevalence of these mutations was significantly lower in pts wild-type either for MYD88 or CXCR4 as compared with those with MYD88 and/or CXCR4 mutations (15% versus 41%, P = 0.04). The prevalence of KMT2D mutations was significantly higher in WM/LPL as compared with MGUS (25% versus 5%), while for the other genes the distribution was not statistically different according to diagnosis. With a median follow-up of 20 months (range: 0-264), we did not find a statistically significant correlation between genetic mutations and pts' outcome in terms of overall survival or time to first treatment. Conclusions. In this cohort of pts with WM/LPL and IgM-MGUS studied with NGS we could demonstrate that: i) NGS identifies MYD88 mutations other than L265P in a small proportion of pts; ii) the prevalence of CXCR4 mutations by Sanger is confirmed by NGS, despite the higher sensitivity of the latter method; iii) the subgroup of pts wild type either for MYD88 or CXCR4 shows a low incidence of other genetic mutations; iv) 25% of pts with WM/LPL were found to carry KMT2D mutations, a prevalence similar to that reported in marginal zone lymphoma; v) genetic mutations are more common in WM/LPL than in IgM-MGUS in agreement with the hypothesis that multiple genetic hits are required for progression from a pre-benign condition to a neoplastic disease; vi) due to the indolent nature of these disorders, longer follow-up is probably needed to see the prognostic impact of these mutations, if any. Disclosures No relevant conflicts of interest to declare.

Mutation of COL2A1 in a Chinese Family with Presentations of Legg-Calvé-Perthes Disease

2020 ◽  
Author(s):  
denglu yan ◽  
zhaojie Wang ◽  
Zhi Zhang
Keyword(s):  
Femoral Head ◽  
Sanger Sequencing ◽  
Structural Changes ◽  
Genetic Factors ◽  
Mutation Detection ◽  
Perthes Disease ◽  
Chinese Family ◽  
Col2a1 Gene ◽  
Whole Exome ◽  
Missense Substitution

Abstract Background: The aim of this study was to identify genetic factors and chromosomal regions contributing to osteonecrosis of the femoral head (ONFH) in a Chinese family with presentations of Legg-Calvé-Perthes Disease (LCDP). Methods: In this study, we performed whole exon sequencing of a Chinese family with LCPD for mutation detection. Ten members had ONFH in twenty-seven family members in four generations family, 5 unaffected members of the studied family and 5 normal peoples as control were underwent whole exome sequencing for mutation detection. Structural modeling test was applied to analyze the potential structural changes caused by the missense substitution. Results: In this Chinese family affected by LCPD, the mutation (c.3508 G>A, p. Gly1170Ser) in exon 50 of COL2A1 in the Gly–X–Y domain was present in 10 patients but absent in 5 unaffected members of the studied family and in 5 control chromosomes from unaffected individuals of matched geographical ancestry. The COL2A1 gene mutation was further validated by Sanger sequencing, confirmed that were heterozygous for the mutation. Then, we identified the p.Gly1170Ser mutation in exon 50 of COL2A1 in a Chinese family with LCPD. Conclusions: This study maps the mutation of mutation (c.3508 G>A, p. Gly1170Ser) in exon 50 of COL2A1 in the Gly–X–Y domain in a Chinese family of LCPD, which causes osteonecrosis of femoral head.

scholarly journals Molecular mechanisms of telomere biology disorders

2020 ◽  
pp. jbc.REV120.014017
Author(s):  
Sherilyn Grill ◽  
Jayakrishnan Nandakumar
Keyword(s):  
Molecular Basis ◽  
Molecular Mechanisms ◽  
Wide Spectrum ◽  
Significant Proportion ◽  
Dyskeratosis Congenita ◽  
Telomere Maintenance ◽  
Genetic Mutations ◽  
Hematopoietic Stem ◽  
Telomere Biology ◽  
Underlying Mechanisms

Genetic mutations that affect telomerase function or telomere maintenance result in a variety of diseases collectively called telomeropathies. This wide spectrum of disorders, which include dyskeratosis congenita (DC), pulmonary fibrosis (PF) and aplastic anemia (AA), is characterized by severely short telomeres, often resulting in hematopoietic stem cell failure in the most severe cases. Recent work has focused on understanding the molecular basis of these diseases. Mutations in the catalytic TERT and TR subunits of telomerase compromise activity, while others, such as those found in the telomeric protein TPP1, reduce the recruitment of telomerase to the telomere. Mutant telomerase-associated proteins TCAB1 and dyskerin, and the telomerase RNA maturation component PARN, affect the maturation and stability of telomerase. In contrast, disease-associated mutations in either CTC1 or RTEL1 are more broadly associated with telomere replication defects. Yet even with the recent surge in studies decoding the mechanisms underlying these diseases, a significant proportion of DC mutations remain uncharacterized or poorly understood. Here we review the current understanding of the molecular basis of telomeropathies and highlight experimental data that illustrate how genetic mutations drive telomere shortening and dysfunction in these patients. This review connects insights from both clinical and molecular studies to create a comprehensive view of the underlying mechanisms that drive these diseases. Through this, we emphasize recent advances in therapeutics and pin-point disease-associated variants that remain poorly defined in their mechanism of action. Finally, we suggest future avenues of research that will deepen our understanding of telomere biology and telomere-related disease.

scholarly journals The distinctive geographic patterns of common pigmentation variants at the OCA2 gene

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kenneth K. Kidd ◽  
Andrew J. Pakstis ◽  
Michael P. Donnelly ◽  
Ozlem Bulbul ◽  
Lotfi Cherni ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Oculocutaneous Albinism ◽  
Selection Effects ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide ◽  
Eye Color ◽  
Geographic Patterns ◽  
Population Genetic Variation ◽  
Oca2 Gene

Abstract Oculocutaneous Albinism type 2 (OCA2) is a gene of great interest because of genetic variation affecting normal pigmentation variation in humans. The diverse geographic patterns for variant frequencies at OCA2 have been evident but have not been systematically investigated, especially outside of Europe. Here we examine population genetic variation in and near the OCA2 gene from a worldwide perspective. The very different patterns of genetic variation found across world regions suggest strong selection effects may have been at work over time. For example, analyses involving the variants that affect pigmentation of the iris argue that the derived allele of the rs1800407 single nucleotide polymorphism, which produces a hypomorphic protein, may have contributed to the previously demonstrated positive selection in Europe for the enhancer variant responsible for light eye color. More study is needed on the relationships of the genetic variation at OCA2 to variation in pigmentation in areas beyond Europe.

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