Altered replication stress response due to CARD14 mutations promotes recombination-induced revertant mosaicism.
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ABSTRACT:
SUBMITTER: Miyauchi T
PROVIDER: S-EPMC8206392 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Revertant mosaicism is an infrequently observed phenomenon caused by spontaneous correction of a pathogenic allele. We have observed such reversions caused by mitotic recombination of mutant TERC (telomerase RNA component) alleles in six patients from four families affected by dyskeratosis congenita (DC). DC is a multisystem disorder characterized by mucocutaneous abnormalities, dystrophic nails, bone-marrow failure, lung fibrosis, liver cirrhosis, and cancer. We identified a 4 nt deletion in TERC in a family with an autosomal-dominant form of DC. In two affected brothers without bone-marrow failure, sequence analysis revealed pronounced overrepresentation of the wild-type allele in blood cells, whereas no such skewing was observed in the other tissues tested. These observations suggest that this mosaic pattern might have resulted from somatic reversion of the mutated allele to the normal allele in blood-forming cells. SNP-microarray analysis on blood DNA from the two brothers indeed showed independent events of acquired segmental isodisomy of chromosome 3q, including TERC, indicating that the reversions must have resulted from mitotic recombination events. Subsequently, after developing a highly sensitive method of detecting mosaic homozygosity, we have found four additional cases with a mosaic-reversion pattern in blood cells; these four cases are part of a cohort of 17 individuals with germline TERC mutations. This shows that revertant mosaicism is a recurrent event in DC. This finding has important implications for improving diagnostic testing and understanding the variable phenotype of DC.
| S-EPMC3309184 | biostudies-literature
Project description:Revertant mosaicism is a phenomenon in which pathogenic mutations are rescued by somatic events, representing a form of natural gene therapy. Here, we report on the first evidence for revertant mosaicism in loricrin keratoderma (LK), an autosomal dominant form of ichthyosis caused by mutations in LOR on 1q21.3. We identified two unrelated LK families exhibiting dozens of previously unreported white spots, which increased in both number and size with age. Biopsies of these spots revealed that they had normal histology and that causal LOR mutations were lost. Notably, dense single nucleotide polymorphism mapping identified independent copy-neutral loss-of-heterozygosity events on chromosome 1q extending from regions centromeric to LOR to the telomere in all investigated spots, suggesting that somatic recombination represents a common reversion mechanism in LK. Furthermore, we demonstrated that reversion of LOR mutations confers a growth advantage to cells in vitro, but the clinically limited size of revertant spots suggests the existence of mechanisms constraining revertant clone expansion. Nevertheless, the identification of revertant mosaicism in LK might pave the way for revertant therapy for this intractable disease.
| S-EPMC6362306 | biostudies-literature
Project description:Revertant mosaicism due to in vivo reversion of an inherited mutation has been described in the genetic skin disease epidermolysis bullosa (EB) for the genes KRT14 and COL17A1. Here we demonstrate the presence of multiple second-site mutations, all correcting the germline mutation LAMB3:c.628G-->A;p.E210K, in 2 unrelated non-Herlitz junctional EB patients with revertant mosaicism. Both probands had a severe reduction in laminin-332 expression in their affected skin. Remarkably, the skin on the lower leg of patient 078-01 (c.628G-->A/c.1903C-->T) became progressively clinically healthy, with normal expression of laminin-332 on previously affected skin. In the other proband, 029-01 (c.628G-->A/c.628G-->A), the revertant patches were located at his arms, shoulder, and chest. DNA analysis showed different second-site mutations in revertant keratinocytes of distinct biopsy specimens (c.565-3T-->C, c.596G-->C;p.G199A, c.619A-->C;p.K207Q, c.628+42G-->A, and c.629-1G-->A), implying that there is not a single preferred mechanism for the correction of a specific mutation. Our data offer prospects for EB treatment in particular cases, since revertant mosaicism seems to occur at a higher frequency than expected. This opens the possibility of applying revertant cell therapy in mosaic EB of the LAMB3 gene by using autologous naturally corrected keratinocytes, thereby bypassing the recombinant gene correction phase.
| S-EPMC1857245 | biostudies-literature
Project description:Psoriasis is a common, immune-mediated genetic disorder of the skin and is associated with arthritis in approximately 30% of cases. Previously, we localized PSORS2 (psoriasis susceptibility locus 2) to chromosomal region 17q25.3-qter after a genome-wide linkage scan in a family of European ancestry with multiple cases of psoriasis and psoriatic arthritis. Linkage to PSORS2 was also observed in a Taiwanese family with multiple psoriasis-affected members. In caspase recruitment domain family, member 14 (CARD14), we identified unique gain-of-function mutations that segregated with psoriasis by using genomic capture and DNA sequencing. The mutations c.349G>A (p.Gly117Ser) (in the family of European descent) and c.349+5G>A (in the Taiwanese family) altered splicing between CARD14 exons 3 and 4. A de novo CARD14 mutation, c.413A>C (p.Glu138Ala), was detected in a child with sporadic, early-onset, generalized pustular psoriasis. CARD14 activates nuclear factor kappa B (NF-kB), and compared with wild-type CARD14, the p.Gly117Ser and p.Glu138Ala substitutions were shown to lead to enhanced NF-kB activation and upregulation of a subset of psoriasis-associated genes in keratinocytes. These genes included chemokine (C-C motif) ligand 20 (CCL20) and interleukin 8 (IL8). CARD14 is localized mainly in the basal and suprabasal layers of healthy skin epidermis, whereas in lesional psoriatic skin, it is reduced in the basal layer and more diffusely upregulated in the suprabasal layers of the epidermis. We propose that, after a triggering event that can include epidermal injury, rare gain-of-function mutations in CARD14 initiate a process that includes inflammatory cell recruitment by keratinocytes. This perpetuates a vicious cycle of epidermal inflammation and regeneration, a cycle which is the hallmark of psoriasis.
| S-EPMC3376640 | biostudies-literature
Project description:Psoriasis is a common, immune-mediated, genetic disorder of the skin associated with arthritis in approximately 30% of cases. Previously, we localized PSORS2 (psoriasis susceptibility locus 2) to chromosome 17q25.3-qter following a genome-wide linkage scan in a family of European origin with multiple cases of psoriasis and psoriatic arthritis. Linkage to PSORS2 was also observed in a multiply affected psoriasis family from Taiwan. With genomic capture and DNA sequencing, we identified unique gain-of-function mutations in caspase recruitment domain family, member 14 (CARD14) that segregated with psoriasis. The mutations, c.349G>A (p.Gly117Ser) and c.349+5G>A respectively, altered splicing between exons 3 and 4 of CARD14. A de novo mutation in CARD14, c.413A>C [p.Glu138Ala], was detected in a child with sporadic, early-onset, generalized pustular psoriasis. CARD14 activates nuclear factor kappa B (NF-kB), and the p.Gly117Ser and p.Glu138Ala substitutions were shown to lead to enhanced NF-kB activation and upregulation of a subset of psoriasis-associated genes in keratinocytes compared to wildtype CARD14. These included chemokine (C-C motif) ligand 20 (CCL20) and interleukin 8 (IL8). CARD14 is localized mainly in the basal and suprabasal layers of healthy skin epidermis, while in lesional psoriatic skin it is reduced in the basal layer and more diffusely upregulated in the suprabasal layers of the lesional epidermis. We propose that, following a triggering event that can include epidermal injury, rare gain-of-function mutations in CARD14 initiate a process that includes inflammatory cell recruitment by keratinocytes. This perpetuates a vicious cycle of epidermal inflammation and regeneration that is the hallmark of psoriasis. No replicates are included. Three sample sets. [1] Skin biopsies had RNA extracted for expression within target tissue. [2] HEK cells were transfected with different constructs (including wildtype) of CARD14 to determine the mutational effect in keratinocytes. [3] Keratinocytes derived from psoriasis patients with CARD14 mutations were cultured and compared with and without stimulation with TNFalpha.
2012-05-08 | E-GEOD-36387 | biostudies-arrayexpress
Project description:In BRCA1/2 families, early-onset breast cancer (BrCa) cases may be also observed among non-carrier relatives. These women are considered phenocopies and raise difficult counselling issues concerning the selection of the index case and the residual risks estimate in negative family members. Few studies investigated the presence of potential genetic susceptibility factors in phenocopies, mainly focussing on BrCa-associated single-nucleotide polymorphisms. We hypothesized that, as for other Mendelian diseases, a revertant somatic mosaicism, resulting from spontaneous correction of a pathogenic mutation, might occur also in BRCA pedigrees. A putative low-level mosaicism in phenocopies, which has never been investigated, might be the causal factor undetected by standard diagnostic testing. We selected 16 non-carriers BrCa-affected from 15 BRCA1/2 families, and investigated the presence of mosaicism through MALDI-TOF mass spectrometry. The analyses were performed on available tumour samples (7 cases), blood leukocytes, buccal mucosa and urine samples (2 cases) or on blood only (7 cases). In one family (n.8), real-time PCR was also performed to analyse the phenocopy and her healthy parents. On the 16 phenocopies we did not detect the family mutations neither in the tumour, expected to display the highest mutation frequency, nor in the other analysed tissues. In family 8, all the genotyping assays did not detect mosaicism in the phenocopy or her healthy parents, supporting the hypothesis of a de novo occurrence of the BRCA2 mutation identified in the proband. These results suggest that somatic mosaicism is not likely to be a common phenomenon in BRCA1/2 families. As our families fulfilled high-risk selection criteria, other genetic factors might be responsible for most of these cases and have a significant impact on risk assessment in BRCA1/2 families. Finally, we found a de novo BRCA2 mutation, suggesting that, although rare, this event should be taken into account in the evaluation of high-risk families.
| S-EPMC5310879 | biostudies-literature
Project description:Revertant mosaicism by somatic reversion of inherited mutations has been described for a number of genetic diseases. Several mechanisms can underlie this reversion process, such as gene conversion, crossing-over, true back mutation, and second-site mutation. Here, we report the occurrence of multiple corrections in two unrelated probands with revertant mosaicism of non-Herlitz junctional epidermolysis bullosa, an autosomal recessive genodermatosis due to mutations in the COL17A1 gene. Immunofluorescence microscopy and laser dissection microscopy, followed by DNA and RNA analysis, were performed on skin biopsy specimens. In patient 1, a true back mutation, 3781T-->C, was identified in the specimen from the arm, and a second-site mutation, 4463-1G-->A, which compensated for the frameshift caused by the inherited 4424-5insC mutation, was identified in the 3' splice site of exon 55 in a specimen from the middle finger. Patient 2 showed--besides two distinct gene conversion events in specimens from the arm and hand sites, both of which corrected the 1706delA mutation--a second-site mutation (3782G-->C) in an ankle specimen, which prevented the premature ending of the protein by the 3781C-->T nonsense mutation (R1226X). Thus, both inherited mutations, paternal as well as maternal, reverted at least once by different reversion events in distinct cell clusters in the described patients. The occurrence of multiple correcting mutations within the same patient indicates that in vivo reversion is less unusual than was generally thought. Furthermore, in the male patient, mosaic patterns of type XVII collagen-positive keratinocytes were present in clinically unaffected and affected skin. This latter observation makes it likely that reversion may be overlooked and may happen more often than expected.
| S-EPMC1271383 | biostudies-literature
Project description:Psoriasis is a common, immune-mediated, genetic disorder of the skin associated with arthritis in approximately 30% of cases. Previously, we localized PSORS2 (psoriasis susceptibility locus 2) to chromosome 17q25.3-qter following a genome-wide linkage scan in a family of European origin with multiple cases of psoriasis and psoriatic arthritis. Linkage to PSORS2 was also observed in a multiply affected psoriasis family from Taiwan. With genomic capture and DNA sequencing, we identified unique gain-of-function mutations in caspase recruitment domain family, member 14 (CARD14) that segregated with psoriasis. The mutations, c.349G>A (p.Gly117Ser) and c.349+5G>A respectively, altered splicing between exons 3 and 4 of CARD14. A de novo mutation in CARD14, c.413A>C [p.Glu138Ala], was detected in a child with sporadic, early-onset, generalized pustular psoriasis. CARD14 activates nuclear factor kappa B (NF-kB), and the p.Gly117Ser and p.Glu138Ala substitutions were shown to lead to enhanced NF-kB activation and upregulation of a subset of psoriasis-associated genes in keratinocytes compared to wildtype CARD14. These included chemokine (C-C motif) ligand 20 (CCL20) and interleukin 8 (IL8). CARD14 is localized mainly in the basal and suprabasal layers of healthy skin epidermis, while in lesional psoriatic skin it is reduced in the basal layer and more diffusely upregulated in the suprabasal layers of the lesional epidermis. We propose that, following a triggering event that can include epidermal injury, rare gain-of-function mutations in CARD14 initiate a process that includes inflammatory cell recruitment by keratinocytes. This perpetuates a vicious cycle of epidermal inflammation and regeneration that is the hallmark of psoriasis.
2012-05-09 | GSE36387 | GEO
Project description:Spontaneous gene repair, also called revertant mosaicism, has been documented in several genetic disorders involving organs that undergo self-regeneration, including the skin. Genetic reversion may occur through different mechanisms, and in a single individual, the mutation can be repaired in various ways. Here we describe a disseminated pattern of revertant mosaicism observed in 6 patients with Kindler syndrome (KS), a genodermatosis caused by loss of kindlin-1 (encoded by FERMT1) and clinically characterized by patchy skin pigmentation and atrophy. All patients presented duplication mutations (c.456dupA and c.676dupC) in FERMT1, and slipped mispairing in direct nucleotide repeats was identified as the reversion mechanism in all investigated revertant skin spots. The sequence around the mutations demonstrated high propensity to mutations, favoring both microinsertions and microdeletions. Additionally, in some revertant patches, mitotic recombination generated areas with homozygous normal keratinocytes. Restoration of kindlin-1 expression led to clinically and structurally normal skin. Since loss of kindlin-1 severely impairs keratinocyte proliferation, we predict that revertant cells have a selective advantage that allows their clonal expansion and, consequently, the improvement of the skin condition.
| S-EPMC3336993 | biostudies-literature
Project description:Revertant mosaicism, or "natural gene therapy", is the phenomenon in which germline mutations are corrected by somatic events. In recent years, revertant mosaicism has been identified in all major types of epidermolysis bullosa, the group of heritable blistering disorders caused by mutations in the genes encoding epidermal adhesion proteins. Moreover, revertant mosaicism appears to be present in all patients with a specific subtype of recessive epidermolysis bullosa. We therefore hypothesized that revertant mosaicism should be expected at least in all patients with recessive forms of epidermolysis bullosa. Naturally corrected, patient-own cells are of extreme interest for their promising therapeutic potential, and their presence in all patients would open exciting, new treatment perspectives to those patients. To test our hypothesis, we determined the probability that single nucleotide reversions occur in patients' skin using a mathematical developmental model. According to our model, reverse mutations are expected to occur frequently (estimated 216x) in each patient's skin. Reverse mutations should, however, occur early in embryogenesis to be able to drive the emergence of recognizable revertant patches, which is expected to occur in only one per ~10,000 patients. This underestimate, compared to our clinical observations, can be explained by the "late-but-fitter revertant cell" hypothesis: reverse mutations arise at later stages of development, but provide revertant cells with a selective growth advantage in vivo that drives the development of recognizable healthy skin patches. Our results can be extrapolated to any other organ with stem cell division numbers comparable to skin, which may offer novel future therapeutic options for other genetic conditions if these revertant cells can be identified and isolated.
| S-EPMC5823395 | biostudies-literature