Mosaic trisomy 12 is a rare anomaly, and only 9 cases of live births with this condition have been reported in the literature. The clinical phenotype is variable, including neuropsychomotor developmental delay, congenital heart disease, microcephaly, cutaneous spots, facial asymmetry, prominent ears, hypotonia, retinopathy, and sensorineural hearing loss. A 2-year-old female presented with neuropsychomotor developmental delay, prominent forehead, dolichocephaly, patchy skin pigmentation, and unexpected overgrowth at birth. Cytogenetic analysis of her peripheral blood showed normal results, suggesting the presence of a chromosomal alteration in other tissues. Further studies using G-banding and FISH performed on fibroblasts from both hyper- and hypopigmented regions identified a 47,XX,+12/46,XX karyotype. To the best of our knowledge, no patients with mosaic trisomy 12 associated with overgrowth have been reported to date. Congenital overgrowth and neonatal overgrowth have been frequently linked to Pallister-Killian syndrome (PKS; OMIM 601803). This case suggests the possibility of an association of genes present in the 12p region with fetal overgrowth, considering that chromosomal duplications could lead to an increase in the production of aberrant transcripts and disturbing gene dosage effects. This case highlights the importance of cytogenetic analysis in different tissues to provide relevant information to the specific genotype/phenotype correlation.
Non-Hodgkin lymphomas are among the most common types of tumors in dogs, and they are currently accepted as comparative models of the disease in humans. Aberrant patterns of DNA methylation seem to play a key role in the development of hematopoietic neoplasms in humans, constitute a special mechanism of transcriptional control, and may be influenced by genetic and environmental factors. Blood leukocyte DNA global methylation has been poorly investigated in dogs. The aim of this study is to examine whether peripheral blood global DNA methylation is associated with canine multicentric lymphomas. Peripheral venous blood samples from ten healthy dogs and nine dogs bearing multicentric lymphomas were collected, and the buffy coat was separated. Global DNA methylation was analyzed by High Performance Liquid Chromatography (HPLC) and immunocytochemistry (ICC). In both analyses, leukocytes from dogs with lymphoma presented lower global DNA methylation than in healthy dogs (HPLC: p = 0.027/ 5MeCyt immunoreactivity scores: p = 0.015). Moderate correlation was observed between the results obtained by HPLC and ICC (correlation coefficient = 0.50). For the identification of differently methylated genes between both groups, the Infinium Human Methylation (HM) EPIC BeadChip (850K) was used. Of the 853,307 CpGs investigated in the microarray, there were 34,574 probes hybridized in the canine samples. From this total, significant difference was observed in the methylation level of 8433 regions, and through the homologous and orthologous similarities 525 differently methylated genes were identified between the two groups. This study is pioneer in suggesting that dogs bearing non-Hodgkin lymphoma presented DNA global hypomethylation of circulating leukocytes compared with healthy dogs. Although canine samples were used in an assay developed specifically for human DNA, it was possible to identify differently methylated genes and our results reiterate the importance of the use of peripheral blood leukocytes in cancer research and possible new biomarkers targets.
OBJECTIVE:The human genome contains several types of variations, such as copy number variations, that can generate specific clinical abnormalities. Different techniques are used to detect these changes, and obtaining an unequivocal diagnosis is important to understand the physiopathology of the diseases. The objective of this study was to assess the diagnostic capacity of multiplex ligation-dependent probe amplification and array techniques for etiologic diagnosis of syndromic patients.METHODS:We analyzed 93 patients with developmental delay and multiple congenital abnormalities using multiplex ligation-dependent probe amplifications and arrays.RESULTS:Multiplex ligation-dependent probe amplification using different kits revealed several changes in approximately 33.3% of patients. The use of arrays with different platforms showed an approximately 53.75% detection rate for at least one pathogenic change and a 46.25% detection rate for patients with benign changes. A concomitant assessment of the two techniques showed an approximately 97.8% rate of concordance, although the results were not the same in all cases. In contrast with the array results, the MLPA technique detected ∼70.6% of pathogenic changes.CONCLUSION:The obtained results corroborated data reported in the literature, but the overall detection rate was higher than the rates previously reported, due in part to the criteria used to select patients. Although arrays are the most efficient tool for diagnosis, they are not always suitable as a first-line diagnostic approach because of their high cost for large-scale use in developing countries. Thus, clinical and laboratory interactions with skilled technicians are required to target patients for the most effective and beneficial molecular diagnosis.
Objective: The purpose of this study was to describe the genomic deoxyribonucleic acid (DNA) methylation profile in fetuses with gastroschisis, determine whether the profile was inherited, and investigate any possible correlations with maternal risk factors. Method: Genome-wide DNA methylation analysis of 96 blood samples was performed using the Illumina Human Methylation 850K BeadChip. The blood samples were collected as follows: 32 from the umbilical cord of fetuses with gastroschisis, 32 from their respective mothers, 16 from the umbilical cord of fetuses without malformation, and 16 from their respective mothers. Results: The differential DNA methylation analysis showed a significant difference between the groups. The enrichment analysis resulted in 12 sites related to T-cell activation (p ¼ 0.0128). The sites with different methylation status contained 10 genes, three of which were related to the beta-2-microglobulin gene. The methylation profile observed in the fetuses with gastroschisis was not inherited from the mothers. In addition, there was no association between maternal urinary tract infection, smoking, and alcohol use and different methylated sites. Conclusion: We established the methylation profile of gastroschisis fetuses, which differs from that of normal fetuses. The profile was not inherited and did not correlate with maternal risk factors. Key Points What is known about this topic? � The etiology and pathogenesis of fetal gastroschisis and its association with environmental factors are not clearly understood, and attempts to identify a biological marker have not been successful. No previous investigation into the methylation patterns in pregnant women carrying fetuses with gastroschisis has been published What does this study add? � This study provides the methylation pattern of fetuses with gastroschisis
Background Cri du chat syndrome (CdCS) is a rare syndrome caused by a partial or complete deletion of the short arm of chromosome 5 (5p‐). The main clinical features include a high‐pitched cry, facial asymmetry, microcephaly, round face at birth, epicanthal folds, hypotonia, delayed growth and development. Methods We studied 14 Brazilian patients with CdCS using genomic array in order to better define the 5p breakpoints and recognize copy number variations (CNVs) that contribute to clinical manifestations associated with the syndrome. Results Array confirmed terminal deletions in 13 patients and an interstitial deletion in one patient. It was also possible to map the breakpoints and associate a genomic region of 4.7 Mb to the development of head circumference and cat‐like cry. We also found other CNVs concomitant to the 5p deletion including a 9p duplication, a 17q deletion, and a 22q deletion in three different patients. Conclusion With advancements of molecular cytogenomic methods in the last two decades, it was possible to evidence cryptic alterations and improve the genotype–phenotype correlation. In this work, we describe a new genomic region associated with microcephaly and cat‐like cry and highlight the importance of precise delineation of 5p deletion breakpoints and detection of other CNVs in CdCS patients to improve genotype–phenotype correlation to perform a complete clinical and molecular diagnosis.
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