scholarly journals Somatic clones heterozygous for recessive disease alleles of BMPR1A exhibit unexpected phenotypes in Drosophila

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Takuya Akiyama ◽  
Sırma D User ◽  
Matthew C Gibson
Keyword(s):  
Somatic Mutation ◽  
Cancer Genetics ◽  
Spontaneous Mutation ◽  
Tissue Level ◽  
Loss Of Function ◽  
Genetic Studies ◽  
Cell Clones ◽  
Heterozygous Carriers ◽  
Disease Initiation ◽  
Central Paradigm

The majority of mutations studied in animal models are designated as recessive based on the absence of visible phenotypes in germline heterozygotes. Accordingly, genetic studies primarily rely on homozygous loss-of-function to determine gene requirements, and a conceptually-related ‘two-hit model’ remains the central paradigm in cancer genetics. Here we investigate pathogenesis due to somatic mutation in epithelial tissues, a process that predominantly generates heterozygous cell clones. To study somatic mutation in Drosophila, we generated inducible alleles that mimic human Juvenile polyposis-associated BMPR1A mutations. Unexpectedly, four of these mutations had no phenotype in heterozygous carriers but exhibited clear tissue-level effects when present in somatic clones of heterozygous cells. We conclude that these alleles are indeed recessive when present in the germline, but nevertheless deleterious when present in heterozygous clones. This unforeseen effect, deleterious heteromosaicism, suggests a ‘one-hit’ mechanism for disease initiation that may explain some instances of pathogenesis associated with spontaneous mutation.

scholarly journals Spondylocarpotarsal synostosis syndrome due to a novel loss of function FLNB variant: a case report

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Samina Yasin ◽  
Outi Makitie ◽  
Sadaf Naz
Keyword(s):  
Short Stature ◽  
Autosomal Recessive ◽  
Autosomal Recessive Disorder ◽  
Loss Of Function ◽  
Case Presentation ◽  
Pathogenic Variants ◽  
Skeletal Malformations ◽  
Tarsal Bones ◽  
The Family ◽  
Heterozygous Carriers

Abstract Background Loss of function or gain of function variants of Filamin B (FLNB) cause recessive or dominant skeletal disorders respectively. Spondylocarpotarsal synostosis syndrome (SCT) is a rare autosomal recessive disorder characterized by short stature, fused vertebrae and fusion of carpal and tarsal bones. We present a novel FLNB homozygous pathogenic variant and present a carrier of the variant with short height. Case presentation We describe a family with five patients affected with skeletal malformations, short stature and vertebral deformities. Exome sequencing revealed a novel homozygous frameshift variant c.2911dupG p.(Ala971GlyfsTer122) in FLNB, segregating with the phenotype in the family. The variant was absent in public databases and 100 ethnically matched control chromosomes. One of the heterozygous carriers of the variant had short stature. Conclusion Our report expands the genetic spectrum of FLNB pathogenic variants. It also indicates a need to assess the heights of other carriers of FLNB recessive variants to explore a possible role in idiopathic short stature.

scholarly journals Loss-of-function polymorphism in IL6R reduces risk of JAK2V617F somatic mutation and myeloproliferative neoplasm: A Mendelian randomization study

2020 ◽  
Vol 21 ◽  
pp. 100280 ◽  
Author(s):  
Kasper Mønsted Pedersen ◽  
Yunus Çolak ◽  
Christina Ellervik ◽  
Hans Carl Hasselbalch ◽  
Stig Egil Bojesen ◽  
...  
Keyword(s):  
Somatic Mutation ◽  
Mendelian Randomization ◽  
Myeloproliferative Neoplasm ◽  
Loss Of Function

scholarly journals Hereditary C2 deficiency: Genetic studies and association with the HL-A system.

1975 ◽  
Vol 141 (6) ◽  
pp. 1464-1469 ◽  
Author(s):  
N K Day ◽  
R L'Esperance ◽  
R A Good ◽  
A F Michael ◽  
J A Hansen ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Genetic Factors ◽  
Recessive Trait ◽  
Autosomal Recessive Trait ◽  
Systemic Lupus ◽  
Genetic Studies ◽  
Large Pedigree ◽  
Deficient Patient ◽  
Heterozygous Carriers ◽  
C2 Deficiency

Herediatary C2-deficiency has been shown to be transmitted asn an autosomal recessive characteristic. Recent evidence indicates that some genetic factors involved in the control of the complement (C) system in both man and mice are governed by genes localized within the major histocompatibility regionmthis study describes a large pedigree of the paternal family of a C2-deficient patient with systemic lupus erythematosusl It is shown that this condition is transmitted as an autosomal recessive trait, the heterozygous carriers having approximately half normal levels of C2. Furthermore, this trait was shown to be inherited in close linkage with an infrequent HL-A typw, 2,4A2. The maternal, C2-defective chromosome was shown to be transmitted by HL-AW10, W18 haplotypemthis same haplotype was described in a similar study by Fu et al. (6) to be associated with C2 deficiencymfinally, a third haplotype HL-A2,W18 carrying a defective C2 gene was demonstrated in a part of this pedigree.

scholarly journals Heterozygous ABCG5 Gene Deficiency and Risk of Coronary Artery Disease

2020 ◽  
Vol 13 (5) ◽  
pp. 417-423 ◽  
Author(s):  
Akihiro Nomura ◽  
Connor A. Emdin ◽  
Hong Hee Won ◽  
Gina M. Peloso ◽  
Pradeep Natarajan ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Large Scale ◽  
Carrier Status ◽  
Loss Of Function ◽  
Increased Risk ◽  
Genetic Deficiency ◽  
Heterozygous Carriers ◽  
Artery Disease ◽  
The Impact

Background: Familial sitosterolemia is a rare Mendelian disorder characterized by hyperabsorption and decreased biliary excretion of dietary sterols. Affected individuals typically have complete genetic deficiency—homozygous loss-of-function (LoF) variants—in the ABCG5 or ABCG8 genes and have substantially elevated plasma sitosterol and LDL (low-density lipoprotein) cholesterol (LDL-C) levels. The impact of partial genetic deficiency of ABCG5 or ABCG8 —as occurs in heterozygous carriers of LoF variants—on LDL-C and risk of coronary artery disease (CAD) has remained uncertain. Methods: We first recruited 9 sitosterolemia families, identified causative LoF variants in ABCG5 or ABCG8 , and evaluated the associations of these ABCG5 or ABCG8 LoF variants with plasma phytosterols and lipid levels. We next assessed for LoF variants in ABCG5 or ABCG8 in CAD cases (n=29 321) versus controls (n=357 326). We tested the association of rare LoF variants in ABCG5 or ABCG8 with blood lipids and risk for CAD. Rare LoF variants were defined as protein-truncating variants with minor allele frequency <0.1% in ABCG5 or ABCG8 . Results: In sitosterolemia families, 7 pedigrees harbored causative LoF variants in ABCG5 and 2 pedigrees in ABCG8 . Homozygous LoF variants in either ABCG5 or ABCG8 led to marked elevations in sitosterol and LDL-C. Of those sitosterolemia families, heterozygous carriers of ABCG5 LoF variants exhibited increased sitosterol and LDL-C levels compared with noncarriers. Within large-scale CAD case-control cohorts, prevalence of rare LoF variants in ABCG5 and in ABCG8 was ≈0.1% each. ABCG5 heterozygous LoF variant carriers had significantly elevated LDL-C levels (25 mg/dL [95% CI, 14–35]; P =1.1×10 −6 ) and were at 2-fold increased risk of CAD (odds ratio, 2.06 [95% CI, 1.27–3.35]; P =0.004). By contrast, ABCG8 heterozygous LoF carrier status was not associated with increased LDL-C or risk of CAD. Conclusions: Although familial sitosterolemia is traditionally considered as a recessive disorder, we observed that heterozygous carriers of an LoF variant in ABCG5 had significantly increased sitosterol and LDL-C levels and a 2-fold increase in risk of CAD.

scholarly journals Are the Somatic Mutation and Tissue Organization Field Theories of Carcinogenesis Incompatible?

2013 ◽  
Vol 12 ◽  
pp. CIN.S13013 ◽  
Author(s):  
Simon Rosenfeld
Keyword(s):  
Somatic Mutation ◽  
Large Scale ◽  
Control Cell ◽  
Tissue Level ◽  
Dna Mutations ◽  
Tissue Organization ◽  
Tissue Organization Field Theory ◽  
Wide Range ◽  
Carcinogenic Agents ◽  
Successful Resolution

Two drastically different approaches to understanding the forces driving carcinogenesis have crystallized through years of research. These are the somatic mutation theory (SMT) and the tissue organization field theory (TOFT). The essence of SMT is that cancer is derived from a single somatic cell that has successively accumulated multiple DNA mutations, and that those mutations occur on genes which control cell proliferation and cell cycle. Thus, according to SMT, neoplastic lesions are the results of DNA-level events. Conversely, according to TOFT, carcinogenesis is primarily a problem of tissue organization: carcinogenic agents destroy the normal tissue architecture thus disrupting cell-to-cell signaling and compromising genomic integrity. Hence, in TOFT the DNA mutations are the effect, and not the cause, of the tissue-level events. Cardinal importance of successful resolution of the TOFT versus SMT controversy dwells in the fact that, according to SMT, cancer is a unidirectional and mostly irreversible disease; whereas, according to TOFT, it is curable and reversible. In this paper, our goal is to outline a plausible scenario in which TOFT and SMT can be reconciled using the framework and concepts of the self-organized criticality (SOC), the principle proven to be extremely fruitful in a wide range of disciplines pertaining to natural phenomena, to biological communities, to large-scale social developments, to technological networks, and to many other subjects of research.

scholarly journals STAT3 mutations indicate the presence of subclinical T-cell clones in a subset of aplastic anemia and myelodysplastic syndrome patients

Blood ◽  
2013 ◽  
Vol 122 (14) ◽  
pp. 2453-2459 ◽  
Author(s):  
Andres Jerez ◽  
Michael J. Clemente ◽  
Hideki Makishima ◽  
Hanna Rajala ◽  
Ines Gómez-Seguí ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Myelodysplastic Syndrome ◽  
Aplastic Anemia ◽  
Somatic Mutation ◽  
Bone Marrow Failure ◽  
Cell Clones ◽  
Key Points ◽  
Stat3 Mutations

Key PointsSTAT3+ T cells are found not only in detected concomitant LGL-BMFs, but in cases in which an LGL expansion was not suspected. Transformation via acquisition of a somatic mutation in T cells may be a mechanism of immune, mainly hypoplastic, bone marrow failure.

scholarly journals Evolution of antibody structure during the immune response. The differentiative potential of a single B lymphocyte.

1989 ◽  
Vol 170 (4) ◽  
pp. 1211-1230 ◽  
Author(s):  
T Manser
Keyword(s):  
Immune Response ◽  
B Cell ◽  
Somatic Mutation ◽  
High Efficiency ◽  
Clonal Expansion ◽  
Isotype Switching ◽  
Cell Clones ◽  
Short Period ◽  
V Region ◽  
Neutral Mutations

Changes in the structure and function of antibodies occur during the course of an immune response due to variable (V) region gene somatic mutation and isotype switch recombination. While the end products of both these processes are now well documented, their mechanisms, timing, and regulation during clonal expansion remain unclear. Here I describe the characterization of antibodies expressed by a large number of hybridomas derived from single B cell clones at an intermediate stage of an immune response. These data provide new insights into the mechanism, relative timing, and potential of V gene mutation and isotype switching. The data suggest that somatic mutation and isotype switching are completely independent processes that may, but need not, occur simultaneously during clonal expansion. In addition, the results of this analysis demonstrate that individual B cell clones are far more efficient than previously imagined at generating and fixing particular V region somatic mutations that result in increased affinity for the eliciting epitope. Models to account for this high efficiency are discussed. Taken together with previous data, the results of this analysis also suggest that the "somatic evolution" of V region structure to a single epitope takes place in two stages; the first in which particular mutations are sustained and fixed by antigen selection in the CDR regions of the V region genes expressed in a clone over a short period of clonal expansion, and the second in which these selected CDR mutations are maintained in the growing clone, deleterious mutations are lost, and selectively neutral mutations accumulate throughout the length of V genes over long periods of clonal expansion.

scholarly journals Papillion-Lefèvre Syndrome: Periodontists’ Perspective

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Sunil Kumar Biraggari ◽  
K. Krishna Mohana Reddy ◽  
J. Sudhakar ◽  
Shiva Shankar Bugude ◽  
Rajesh Nichenametla ◽  
...  
Keyword(s):  
Gene Locus ◽  
Autosomal Recessive ◽  
Major Gene ◽  
Autosomal Recessive Inheritance ◽  
Signs And Symptoms ◽  
Loss Of Function ◽  
Gingival Inflammation ◽  
Deciduous Dentition ◽  
Genetic Studies ◽  
Present Case Report

Papillion-Lefèvre Syndrome is a very rare disorder of autosomal recessive inheritance distinguished by palmar plantar hyperkeratosis and early onset of periodontitis affecting the dentition. Genetic studies have identified a mutation in the major gene locus of chromosome 11q14 with loss of function. Cathepsin C gene is to be responsible for Papillion-Lefèvre Syndrome. The present case report describes a 13-year-old female, who visited the Department of Periodontology with the chief compliant of bleeding gums and loose teeth. She presented with the signs and symptoms of Papillion-Lefèvre Syndrome. The patient had premature shedding of her deciduous dentition. On clinical examination, extraorally, the patient presented with persistent thickening, flaking, and scaling of the skin of palms and soles. Her intraoral examination revealed gingival inflammation, abscess formation, and periodontal pockets. Her intraoral radiographs showed bone loss involving the central incisors and molars. The patient underwent periodontal therapy and is under maintenance.

scholarly journals Genome-Wide Identification and Characterization of MLO Gene Family in Octoploid Strawberry (Fragaria ×ananassa)

2020 ◽  
Author(s):  
Ronald R. Tapia ◽  
Christopher R. Barbey ◽  
Saket Chandra ◽  
Kevin M. Folta ◽  
Vance M. Whitaker ◽  
...  
Keyword(s):  
Gene Family ◽  
Genomic Structure ◽  
Resistance Locus ◽  
Fragaria Ananassa ◽  
Loss Of Function ◽  
Genetic Studies ◽  
Genome Wide ◽  
Segregating Population

AbstractPowdery mildew (PM) caused by Podosphaera aphanis is a major fungal disease in cultivated strawberry. Mildew Resistance Locus O (MLO) is a gene family described for having conserved seven-transmembrane domains. Induced loss-of-function in specific MLO genes can confer durable and broad resistance against PM pathogens. However, the underlying biological role of MLO genes in strawberry is still unknown. In the present study, the genomic structure of MLO genes were characterized in both diploid (Fragaria vesca) and octoploid strawberry (Fragaria ×ananassa), and the potential sources of MLO-mediated susceptibility were identified. Twenty MLO-like sequences were identified in F. vesca, with sixty-eight in F. ×ananassa. Phylogenetic analysis divides strawberry MLO genes into eight different clades, in which three FveMLO and ten FaMLO genes were grouped together with the functionally known MLO susceptibility. Out of ten FaMLO genes, FaMLO17-2 and FaMLO17-3 showed the highest similarity to the known susceptibility MLO proteins. Gene expression analysis of FaMLO genes was conducted using a multi-parental segregating population. Three expression quantitative trait loci (eQTL) were substantially associated with MLO transcript levels in mature fruits, suggesting discrete genetic control of susceptibility. These results are a critical first step in understanding allele function of MLO genes, and are necessary for further genetic studies of PM resistance in cultivated strawberry.

scholarly journals Pitch temperatures in traditional farmhouse brewing

2020 ◽  
Author(s):  
Lars Marius Garshol
Keyword(s):  
High Temperature ◽  
Body Temperature ◽  
Local Community ◽  
Temperature Tolerance ◽  
Northern Europe ◽  
Loss Of Function ◽  
Brewer’S Yeast ◽  
Genetic Studies ◽  
Wild Yeast ◽  
High Temperature Tolerance

Historically, farmhouse brewers brewed beer from their own grain all over northern Europe, using yeast they maintained in the local community. A large proportion of them, perhaps around 60%, fermented at temperatures close to body temperature, according to a survey of 287 independent accounts of farmhouse brewing practices in 10 different countries. Recent genetic studies indicate that this was possible because the yeasts used in farmhouse brewing, although domesticated, were different from those used in modern brewing. Since wild yeast appears to have high temperature tolerance and modern commercial brewing arose out of earlier farmhouse brewing practices, it seems that the lack of high temperature tolerance in modern brewer’s yeast may be due to a loss of function as the yeast adapted to commercial brewing practices.

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