Low concentrations of permethrin and malathion induce numerical and structural abnormalities in KMT2A and IGH genes in vitro.

Pesticides are commonly used worldwide and almost every human is potentially exposed to these chemicals. Exposure to pesticides such as permethrin and malathion has been associated with hematological malignancies in epidemiological studies. However, biological evidence showing if these chemicals induce genetic aberrations involved in the etiology of leukemia and lymphoma is missing. In our previous work, we have shown that a single high exposure (200 µm, 24 hours) of permethrin and malathion induce damage in genes associated with hematological malignancies in peripheral blood mononuclear cells analyzed by interphase fluorescence in situ hybridization (FISH). In the present study, we assessed by FISH whether exposure to low concentrations (0.1 µm, 72 hours) of permethrin and malathion induce aberrations in KMT2A and IGH genes, which are involved in the etiology of leukemia and lymphoma. Peripheral blood mononuclear cells were exposed to the chemicals, and damage in these genes was assessed on interphases and metaphases. We observed that both chemicals at low concentration induced structural aberrations in KMT2A and IGH genes. A higher level of damage was observed in KMT2A gene with malathion treatment and in IGH gene with permethrin exposure. We also observed numerical aberrations induced by these chemicals. The most frequent aberrations detected on interphase FISH were also observed on metaphases. Our results show that permethrin and malathion induce genetic damage in genes associated with hematological cancer, at concentrations biologically relevant. In addition, damage was observed on dividing cells, which suggests that these cells maintain their proliferation capacity in spite of the genetic damage they possess.

Cytogenomic characterization of small supernumerary marker chromosomes in patients with pigmentary mosaicism.

Introduction: The combination of gene content on the marker chromosome, chromosomal origin, level of mosaicism, origin mechanism (chromothripsis), and uniparental disomy can influence the final characterization of sSMCs. Several chromosomal aberrations, including sSMCs, have been observed in 30%-60% of patients with pigmentary mosaicism, and in more than 80%, chromosomal abnormalities are present in the mosaic state. In patients with pigmentary mosaicism the most representative chromosomes involved in sSMCs are 3, 5, 6, 9, 10, 13, 15, 18, 20, and X. In this study, we included the complete clinical, cytogenetic, and molecular characterization of seven patients with pigmentary mosaicism associated with the presence of SMCs of different chromosomal origins. Methods: The patients were diagnosed by the Genetics and Dermatology Department of three different hospitals. Cytogenetic and FISH analyses were performed on peripheral blood, light skin, and dark skin. FISH analysis was performed using different probes, depending on the marker chromosome description. Different array analysis was performed. Results: To date, of the seven cases studied, the chromosomal origins of six were successfully identified by FISH or array analysis. The chromosomes involved in SMCs were 6, 9, 15, and 18, X. The most frequently found was the centric minute structure. Discussion: To date, this group of seven patients constitutes the largest clinical and cytogenetically finely described study of cases with pigmentary mosaicism associated with sSMCs. Undoubtedly, analysis of the two skin types is a fundamental part of our study, as numerical differences may occur in the cell lines found in each skin type. The knowledge generated in this study will help delineate a very heterogeneous entity more accurately, and in the future, analyzing more patients with PM will likely establish a more definite association with the presence of this genetic alteration.

Pigmentary mosaicism as a recurrent clinical manifestation in three new patients with mosaic trisomy 12 diagnosed postnatally: cases report and literature review.

BACKGROUND: To date, only twenty-one cases diagnosed postnatally with mosaic trisomy 12 have been reported. The most frequent phenotypic manifestations are developmental delay, dysmorphic facial features, congenital heart defects, digital alterations, and pigmentary disorders. In the present report, detailed clinical and genetic profiles of three unrelated new patients with mosaic trisomy 12 are described and compared with previously reported cases. CASE PRESENTATION: In the present report, we include the clinical, cytogenetic, and molecular description of three Mexican patients diagnosed postnatally with mosaic trisomy 12. At phenotypic level, the three patients present with developmental delay, dysmorphic facial features, congenital heart defects and skin pigmentary anomalies. Particularly, patient 1 showed unique eye alterations as bilateral distichiasis, triple rows of upper lashes, and digital abnormalities. In patient 2 redundant skin, severe hearing loss, and hypotonia were observed, and patient 3 presented with hypertelorism and telecanthus. Hyperpigmentation with disseminated pigmentary anomalies is a common trait in all of them. The cytogenetic study was carried out under the strict criteria of analysis, screening 50-100 metaphases from three different tissues, showing trisomy 12 mosaicism in at least one of the three different tissues analyzed. With SNParray, the presence of low-level mosaic copy number variants not previously detected by cytogenetics, and uniparental disomy of chromosome 12, was excluded. STR markers allowed to confirm the absence of uniparental disomy as well as to know the parental origin of supernumerary chromosome 12. CONCLUSIONS: The detailed clinical, cytogenetic, and molecular description of these three new patients, contributes with relevant information to delineate more accurately a group of patients that show a heterogeneous phenotype, although sharing the same chromosomal alteration. The possibility of detecting mosaic trisomy 12 is directly associated with the sensitivity of the methodology applied to reveal the low-level chromosomal mosaicism, as well as with the possibility to perform the analysis in a suitable tissue.

UPD(14)mat and UPD(14)mat in concomitance with mosaic small supernumerary marker chromosome 14 in two new patients with Temple syndrome.

Temple syndrome (TS14) can be originated by maternal uniparental disomy (UPD(14)mat), paternal deletion, or epimutation, leading to disturbances in 14q32.2 imprinted region. The most frequent phenotypic manifestations are prenatal and postnatal growth failure, hypotonia, developmental delay, small hands/feet, precocious puberty, and truncal obesity. However, the diagnosis can be challenging due to the clinical overlap with other imprinting disorders such as Silver-Russell or Prader-Willi syndromes. Although rare, TS14 has been also reported in patients with concomitant UPD(14)mat and mosaic trisomy 14. In the present report, the clinical and genetic profiles of two new patients with TS14 are described. SNParray and MS-MLPA, allowed the determination of segmental UPD(14)mat and the hypomethylation of MEG3 gene. Additionally, in one of our patients we also observed by cytogenetics a small supernumerary marker chromosome that led to partial trisomy 14 in mosaic. Only few patients with concomitant UPD(14)mat and mosaic partial trisomy 14 have been reported. Our patients share cardinal TS14 phenotypic features that are associated to the genetic abnormalities detected; however, we also observed some clinical features such as fatty liver disease that had not previously been reported as part of this syndrome. The detailed clinical, cytogenetical and molecular description of these two new patients, contributes to a more accurately delineation of this syndrome.

Genetic and clinical characterization of 73 Pigmentary Mosaicism patients: revealing the genetic basis of clinical manifestations.

BACKGROUND: Pigmentary mosaicism constitutes a heterogeneous group of skin pigmentation alterations associated with multisystem involvement. The aim of this study was to establish a complete cytogenetic and molecular characterization of PM patients, emphasizing on searching for possible low chromosomal mosaicism and on establishing an accurate genotype-phenotype correlation. RESULTS: A total of 73 patients were included (3 months to 18 years of age), 52% male and 48% female. Observed in 69 (95%) patients, the most frequent pattern of pigmentation was fine and whorled BL, which was associated with disseminated skin extent in 41 (59%) patients. Central nervous system (84%) alterations were the most frequent observed in the group of patients, followed by the musculoskeletal (53%) and ophthalmologic (27%) alterations. Considering the pattern of pigmentation, no significant differences in association with skin extent or extracutaneous manifestations were detected. Following a strict cytogenetic analysis strategy, screening metaphases from three different tissues (peripheral blood, hyperpigmented and hypopigmented skin) we found that 23/73 patients had chromosomal abnormalities classified as follows: 1) Mosaic with 2 or more different cell lines with structural alterations n = 19; 2) Polyploidy (mosaic) n = 1 and 3) Alterations in all cells in three different tissues n = 3. SNP array, array CGH and FISH were useful for the complete characterization of the chromosomal aberrations, for the detection of microdeletions in patients with normal karyotype but with strong clinical suspicious of chromosomal alteration, and for a better establishment of genotype-phenotype correlation. In 2 patients we found genes associated with some of the extracutaneous manifestations (SHH, MNX1, PPP2R2C). CONCLUSIONS: This group of 73 patients finely described is the largest series of patients with pigmentary mosaicism reported worldwide. As we showed in this study, the followed analysis strategy allowed the detection of cytogenetic and molecular abnormalities, and made possible the establishment of genotype-phenotype associations in some patients. An important limitation of our study was the analysis of fibroblasts cultures instead of melanocytes and keratinocytes. In some cases the direct molecular DNA analysis of skin biopsy could be another choice.

"Exposure to the insecticides permethrin and malathion induces leukemia and lymphoma-associated gene aberrations in vitro".

Epidemiological studies have associated the exposure to permethrin and malathion with increased risk of leukemia and lymphoma. The aim of this study was to evaluate whether in vitro exposure to permethrin and malathion induces aberrations in genes involved in the etiology of these hematological malignancies. Genetic abnormalities in the IGH, KMT2A (MLL), ETV6 and RUNX1 genes, and aneuploidy induced by the in vitro exposure to permethrin and malathion (200µM, 24h), were analyzed by FISH in peripheral blood mononuclear cells (PBMCs). The gene fusions IGH-BCL2, KMT2A-AFF1 and ETV6-RUNX1 were further analyzed with nested RT-PCR in PBMCs, and in K562 cells exposed to acute and chronic treatments (0.1µM, 24h or every third day for two weeks) of insecticides. FISH analysis revealed that permethrin induces aneuploidy and structural alterations in IGH and KMT2A genes, and malathion induces breaks in KMT2A. RT-PCR detected ETV6-RUNX1 fusion in PBMCs acutely exposed to permethrin. Permethrin also induced ETV6-RUNX1 and IGH-BCL2 fusions in K562 cells, and malathion induced KMT2A-AFF1 and ETV6-RUNX1 fusions. Overall, we identified that both insecticides induce breaks and fusions in the studied genes, and permethrin induces aneuploidy. This study presents evidence of damage in cancer genes caused by these insecticides.