Tatiane Cristina Rodrigues

Deletion of the RMGA and CHD2 genes in a child with epilepsy and mental deficiency

We describe a novel chromosome microdeletion at 15q26.1 detected by oligo-array-CGH in a 6-year-old girl presenting with global development delay, epilepsy, autistic behavior and facial dysmorphisms. Although these features are often present in Angelman syndrome, no alterations were present in the methylation pattern of the Prader-Willi-Angelman critical region. The deletion encompasses only 2 genes: CHD2, which is part of a gene family already involved in CHARGE syndrome, and RGMA which exerts a negative control on axon growth. Deletion of either or both genes could cause the phenotype of this patient. These results provide a further chromosome region requiring evaluation in patients presenting Angelman features.

Genome-wide screening of copy number variants in children born small for gestational age reveals several candidate genes involved in growth pathways

BACKGROUND The etiology of prenatal-onset short stature with postnatal persistence is heterogeneous. Submicroscopic chromosomal imbalances, known as copy number variants (CNVs), may play a role in growth disorders. OBJECTIVE To analyze the CNVs present in a group of patients born small for gestational age (SGA) without a known cause. PATIENTS AND METHODS A total of 51 patients with prenatal and postnatal growth retardation associated with dysmorphic features and/or developmental delay, but without criteria for the diagnosis of known syndromes, were selected. Array-based comparative genomic hybridization was performed using DNA obtained from all patients. The pathogenicity of CNVs was assessed by considering the following criteria: inheritance; gene content; overlap with genomic coordinates for a known genomic imbalance syndrome; and overlap with CNVs previously identified in other patients with prenatal-onset short stature. RESULTS In 17 of the 51 patients, 18 CNVs were identified. None of these imbalances has been reported in healthy individuals. Nine CNVs, found in eight patients (16%), were categorized as pathogenic or probably pathogenic. Deletions found in three patients overlapped with known microdeletion syndromes (4q, 10q26, and 22q11.2). These imbalances are de novo, gene rich and affect several candidate genes or genomic regions that may be involved in the mechanisms of growth regulation. CONCLUSION Pathogenic CNVs in the selected patients born SGA were common (at least 16%), showing that rare CNVs are probably among the genetic causes of short stature in SGA patients and revealing genomic regions possibly implicated in this condition.

Lymphovascular invasion and histologic grade are associated with specific genomic profiles in invasive carcinomas of the breast

Lymphovascular invasion (LVI) and histologic grade are clinical parameters of high prognostic value in breast cancer and indicate the level of tumor aggressiveness. Many studies have focused on the association of breast cancer subtypes with gene expression and chromosomal profiles, but considerably less genomic information is available regarding traditional prognostic factors such as histologic grade and LVI. We studied by array-CGH a group of 57 invasive ductal carcinomas of the breast to outline the DNA copy number aberration (CNA) profile linked to high histologic grades and LVI. Selected CNAs were validated using real-time quantitative PCR (qPCR). Furthermore, gene expression analysis was performed in a subset of 32 of these tumors, and findings were integrated with array-CGH data. Our findings indicated an accumulation of genomic alterations in high-grade breast tumors compared to low-grade samples. Grade III tumors showed higher number of CNAs and larger aberrations than low-grade tumors and displayed a wide range of chromosomal aberrations, which were mainly 5p, 8q, 10p, 17q12, and 19 gains, and 3p, 4, 5q proximal, 9p, 11p, 18q, and 21 losses. The presence of LVI, a well-established prognostic marker, was not significantly associated with increased genomic instability in comparison to breast tumors negative for LVI, considering the total number of chromosomal alterations. However, a slightly increase in the frequency of specific alterations could be detected in LVI-positive group, such as gains at 5p, 16p, 17q12, and 19, and losses at 8p, 11q, 18q, and 21. Three newly reported small-scale rearrangements were detected in high-risk tumors (LVI-positive grade III) harboring putative breast cancer genes (amplicons at 4q13.3 and 11p11.2, and a deletion at 12p12.3). Furthermore, gene expression analysis uncovered networks highlighting S100A8, MMP1, and MED1 as promising candidate genes involved in high-grade and LVI-positive tumors. In summary, a group of genomic regions could be associated with high-risk tumors, and expression analysis pinpointed candidate genes deserving further investigation. The data has shed some light on the molecular players involved in two highly relevant prognostic factors and may further add to the understanding of the mechanisms of breast cancer aggressiveness.

Upregulated genes at 2q24 gains as candidate oncogenes in hepatoblastomas

AIM Cytogenetic data of hepatoblastomas, a rare embryonal tumor of the liver, mostly consist of descriptions of whole-chromosome aneuploidies and large chromosome alterations. High-resolution cytogenetics may provide clues to hepatoblastoma tumorigenesis and indicate markers with clinical significance. PATIENTS & METHODS We used array-CGH (180K) to screen for genomic imbalances in nine hepatoblastomas. Additionally, we investigated the expression pattern of selected genes exhibiting copy number changes. RESULTS Analysis showed mainly whole-chromosome or chromosome-arm aneuploidies, but some focal aberrations were also mapped. Expression analysis of 48 genes mapped at one 10 Mb amplification at 2q24 revealed upregulation of DAPL1, ERMN, GALNT5, SCN1A and SCN3A in the set of tumors compared with differentiated livers. CONCLUSION These genes appear as candidates for hepatoblastoma tumorigenesis.

Genome-wide DNA methylation profile of leukocytes from melanoma patients with and without CDKN2A mutations.

Melanoma is a highly aggressive cancer, accounting for up to 75% of skin cancer deaths. A small proportion of melanoma cases can be ascribed to the presence of highly penetrant germline mutations, and approximately 40% of hereditary melanoma cases are caused by CDKN2A mutations. The current study sought to investigate whether the presence of germline CDKN2A mutations or the occurrence of cutaneous melanoma would result in constitutive genome-wide DNA methylation changes. The leukocyte methylomes of two groups of melanoma patients (those with germline CDKN2A mutations and those without CDKN2A mutations) were analyzed together with the profile of a control group of individuals. A pattern of DNA hypomethylation was detected in the CDKN2A-negative patients relative to both CDKN2A-mutated patients and controls. Additionally, we delineated a panel of 90 CpG sites that were differentially methylated in CDKN2A-mutated patients relative to controls. Although we identified a possible constitutive epigenetic signature in CDKN2A-mutated patients, the occurrence of reported SNPs at the detected CpG sites complicated the data interpretation. Thus, further studies are required to elucidate the impact of these findings on melanoma predisposition and their possible effect on the penetrance of CDKN2A mutations.

Dental developmental abnormalities in a patient with subtelomeric 7q36 deletion syndrome may confirm a novel role for the SHH gene.

Studies in mice demonstrated that the Shh gene is crucial for normal development of both incisors and molars, causing a severe retardation in tooth growth, which leads to abnormal placement of the tooth in the jaw and disrupted tooth morphogenesis. In humans the SHH gene is located on chromosome 7q36. Defects in its protein or signaling pathway may cause holoprosencephaly spectrum, a disorder in which the developing forebrain fails to correctly separate into right and left hemispheres and that can be manifested in microforms such as single maxillary central incisor. A novel role for this gene in the developing human primary dentition was recently demonstrated. We report a 12-year old boy with a de novo 7q36.1-qter deletion characterized by high-resolution karyotyping, oligonucleotide aCGH and FISH. His phenotype includes intellectual disability, non-verbal communication, hypospadia, partial sacral agenesis and absence of coccyx, which are distinctive features of the syndrome and mainly correlated with the MNX1, HTR5A and EN2 genes. No microforms of holoprosencephaly spectrum were observed; but the patient had diastema and dental developmental abnormalities, such as conical, asymmetric and tapered inferior central incisors. The dental anomalies are reported herein for the first time in subtelomeric 7q36 deletion syndrome and may confirm clinically a novel role for the SHH gene in dental development.

Role of rare germline copy number variation in melanoma-prone patients

AIM This work evaluates a possible causative role for germline copy number variants (CNVs) in melanoma predisposition. PATIENTS & METHODS A total of 41 melanoma-prone Brazilian patients were investigated for CNVs using 850K single nucleotide polymorphism arrays. RESULTS Ten rare CNVs were identified in nine patients, comprising 54 known genes, mostly related to cancer. In silico analyses revealed gene enrichment for cellular development and growth, and proliferation, highlighting five genes directly associated with the melanoma phenotype (ANGPT1, IDH1, PDE5A, HIST1H1B and GCNT2). CONCLUSION Patients harboring rare CNVs exhibited a decreased age of disease onset, in addition to an overall higher skin cancer predisposition. Our findings suggest that rare CNVs contribute to melanoma susceptibility, and should be taken into account when investigating cancer risk factors.

DNA methylation landscape of hepatoblastomas reveals arrest at early stages of liver differentiation and cancer-related alterations

Hepatoblastomas are uncommon embryonal liver tumors accounting for approximately 80% of childhood hepatic cancer. We hypothesized that epigenetic changes, including DNA methylation, could be relevant to hepatoblastoma onset. The methylomes of eight matched hepatoblastomas and non-tumoral liver tissues were characterized, and data were validated in an independent group (11 hepatoblastomas). In comparison to differentiated livers, hepatoblastomas exhibited a widespread and non-stochastic pattern of global low-level hypomethylation. The analysis revealed 1,359 differentially methylated CpG sites (DMSs) between hepatoblastomas and control livers, which are associated with 765 genes. Hypomethylation was detected in hepatoblastomas for ~58% of the DMSs with enrichment at intergenic sites, and most of the hypermethylated CpGs were located in CpG islands. Functional analyses revealed enrichment in signaling pathways involved in metabolism, negative regulation of cell differentiation, liver development, cancer, and Wnt signaling pathway. Strikingly, an important overlap was observed between the 1,359 DMSs and the CpG sites reported to exhibit methylation changes through liver development (p<0.0001), with similar patterns of methylation in both hepatoblastomas and fetal livers compared to adult livers. Overall, our results suggest an arrest at early stages of liver cell differentiation, in line with the hypothesis that hepatoblastoma ontogeny involves the disruption of liver development. This genome-wide methylation dysfunction, taken together with a relatively small number of driver genetic mutations reported for both adult and pediatric liver cancers, shed light on the relevance of epigenetic mechanisms for hepatic tumorigenesis.Hepatoblastomas are uncommon embryonal liver tumors accounting for approximately 80% of childhood hepatic cancer. We hypothesized that epigenetic changes, including DNA methylation, could be relevant to hepatoblastoma onset. The methylomes of eight matched hepatoblastomas and non-tumoral liver tissues were characterized, and data were validated in an independent group (11 hepatoblastomas). In comparison to differentiated livers, hepatoblastomas exhibited a widespread and non-stochastic pattern of global low-level hypomethylation. The analysis revealed 1,359 differentially methylated CpG sites (DMSs) between hepatoblastomas and control livers, which are associated with 765 genes. Hypomethylation was detected in hepatoblastomas for ~58% of the DMSs with enrichment at intergenic sites, and most of the hypermethylated CpGs were located in CpG islands. Functional analyses revealed enrichment in signaling pathways involved in metabolism, negative regulation of cell differentiation, liver development, cancer, and Wnt signaling pathway. Strikingly, an important overlap was observed between the 1,359 DMSs and the CpG sites reported to exhibit methylation changes through liver development (p<0.0001), with similar patterns of methylation in both hepatoblastomas and fetal livers compared to adult livers. Overall, our results suggest an arrest at early stages of liver cell differentiation, in line with the hypothesis that hepatoblastoma ontogeny involves the disruption of liver development. This genome-wide methylation dysfunction, taken together with a relatively small number of driver genetic mutations reported for both adult and pediatric liver cancers, shed light on the relevance of epigenetic mechanisms for hepatic tumorigenesis.

Abstract 3418: Rare germline copy number variations in hereditary cutaneous melanoma

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Background: Melanoma is a highly aggressive skin cancer; approximately 10% of melanomas are caused by germline mutations, mainly affecting the p16 isoform of the CDKN2A gene (responsible for up to 40% of the familial melanoma). Although other genes exhibiting moderate to high penetrant mutations have been recently associated with melanoma susceptibility, such as CDK4, PALB2, MITF, and TERT promoter, the majority of the melanoma susceptibility remains without a clear genetic etiology. Copy number variations (CNVs) are a common class of structural variants of the human genome, mainly impacting genes that mediate the interaction with environment. However, many rare germline CNVs have been causally associated with diseases, including mental impairment and cancer predisposition. Objective: Aiming to identify new genes potentially related to melanoma predisposition, 34 melanoma-prone patients negative for CDKN2A/CDK4 mutations were investigated for rare germline CNVs. Material and Methods: Patients - patients were ascertained at the A. C. Camargo Cancer Center, Sao Paulo, Brazil; signed informed consents were obtained from all patients. DNA samples from peripheral blood were extracted from 34 unrelated probands fulfilling either the classical criteria for familial melanoma syndrome or based on evidence of a strong genetic predisposition (occurrence of ≥2 primary melanomas). These patients had been previously tested negative for CDKN2A and CDK4 genes. Methods - we performed evaluation of germline CNVs using the CytoSNP-850K (Illumina), analyzing data in the BlueFuse Multi Software v3.2. Selected CNVs were validated by real-time quantitative PCR (qPCR). Results: Among the 34 patients, we detected rare CNVs in 9 of them, mainly large duplications (>230kb) at 4q26-q27, 6p22.1, 8q23.1, 9p24.2, 10q22.3, 12p12.3 and 20p12.1, and deletions affecting 6p24.3 and 19p13.3. Four of these changes in DNA copy number were validated by qPCR using probes for genes mapped within affected regions (ANXA11, ESF1, MGST1 and ANGPT1 genes). Conclusion: We found 26% of the melanoma-prone patients carrying rare germline CNVs that encompass genes potentially associated with melanoma predisposition. Our data suggest that melanoma susceptibility could be originated by a broad spectrum of no recurrent genomic alterations, and part of the genetic etiology of the hereditary melanoma might reside in rare germline copy number changes. In addition to the well-known melanoma genes, germline CNVs, here reported, disclosed other candidate genes to melanoma predisposition deserving further investigation. Funding: This work was supported by grants from FAPESP (2012/21932-6) and the Brazilian National Institute of Science and Technology in Oncogenomics (FAPESP 2008/57887-9, CNPq 573589/08-9). Citation Format: Felipe Fidalgo, Tatiane Rodrigues, Amanda Goncalves Silva, Luciana Facure, Amanda Nobrega, Bianca Sa, Joao Pereira Duprat, Maria Isabel Achatz, Carla Rosenberg, Dirce Maria Carraro, Ana Cristina Krepischi. Rare germline copy number variations in hereditary cutaneous melanoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3418. doi:10.1158/1538-7445.AM2014-3418

Genome-wide profiling of copy number alterations in triple-negative breast cancer identifies a region at 19p13 associated with lymph node metastasis

Background The acquisition of somatic alterations (point mutations/ chromosomal rearrangements) underlies the hallmarks of cancer, generating genetic diversity that drives tumorigenesis. Advances in the study of cancer genomes revealed in solid tumors a complex pattern of copy number alterations (CNA), structural rearrangements, and aneuplodies. Breast cancer (BC) is the most common malignancy in females, being the leading cause of death by cancer. This heterogeneous disease is not fully understood yet; however, genomic studies have identified unique CNA patterns in different BC subtypes. Regarding the subtype triple-negative (TN; estrogen and progesterone receptors, and HER2 negative expression levels), only limited data are available on which genes or chromosome regions are involved in its initiation and progression.