ABSTRACT: Genome wide DNA methylation profiling of peripheral blood cells from WHS and several disease patients. The Illumina Infinium EPIC Human DNA methylation Beadchip was used to obtain DNA methylation profiles across approximately 850,000 CpGs in peripheral blood samples. Samples included, 20 WHS, 1 patient with heterozygous deletion in 4p16.2p15.31, 2 Sotos syndrome patients, 2 Kabuki syndrome patients, 1 CHARGE syndrome patient, and 3 patients who harbor NSD2 de novo variants.
Project description:Kabuki syndrome is a monogenic disorder caused by loss of function variants in either of two genes encoding histone-modifying enzymes. We performed targeted sequencing in a cohort of 27 probands with a clinical diagnosis of Kabuki syndrome. Of these, 12 had causative variants in the two known Kabuki syndrome genes. In 2, we identified presumptive loss of function de novo variants in KMT2A (missense and splice site variants), a gene that encodes another histone modifying enzyme previously exclusively associated with Wiedermann-Steiner syndrome. Although Kabuki syndrome is a disorder of histone modification, we also find alterations in DNA methylation among individuals with a Kabuki syndrome diagnosis relative to matched normal controls, regardless of whether they carry a variant in KMT2A or KMT2D or not. Furthermore, we observed characteristic global abnormalities of DNA methylation that distinguished patients with a loss of function variant in KMT2D or missense or splice site variants in either KMT2D or KMT2A from normal controls. Our results provide new insights into the relationship of genotype to epigenotype and phenotype and indicate cross-talk between histone and DNA methylation machineries exposed by inborn errors of the epigenetic apparatus.
Project description:Enzymes catalyzing CpG methylation in DNA, including DNMT1 and DNMT3A/B, are indispensable for mammalian tissue development and homeostasis. They are also implicated in human developmental disorders and cancers, supporting a critical role of DNA methylation during cell fate specification and maintenance. Recent studies suggest that histone post-translational modifications (PTMs) are involved in specifying patterns of DNMT localization and DNA methylation at promoters and actively transcribed gene bodies. However, mechanisms governing the establishment and maintenance of intergenic DNA methylation remain poorly understood. Germline mutations in DNMT3A lead to a childhood overgrowth syndrome that is phenotypically overlapping with Sotos syndrome caused by haploinsufficiency of NSD1, a histone methyltransferase catalyzing di-methylation on H3K36 (H3K36me2), pointing to a potential mechanistic link between the two disorders. Here we report that NSD1-mediated H3K36me2 is required for recruitment of DNMT3A and maintenance of DNA methylation at intergenic regions. Genome-wide analysis shows binding and activity of DNMT3A are co-localized with H3K36me2 at non-coding regions of euchromatin. Genetic ablation of NSD1 and its paralogue NSD2 in mouse and human cells redistributes DNMT3A to H3K36me3-marked gene bodies and reduces intergenic DNA methylation. NSD1 mutant tumors and Sotos patient samples are also associated with intergenic DNA hypomethylation. Consistently, PWWP-domain of DNMT3A shows dual recognition of H3K36me2/3 in vitro with a higher binding affinity towards H3K36me2, which is abrogated by overgrowth syndrome-derived missense mutations. Taken together, our study uncovers a trans-chromatin regulatory pathway that, when perturbed, promotes neoplastic and developmental overgrowth.
Project description:Genome-wide expression studies were performed on dermal fibroblasts from Sotos syndrome patients with a confirmed NSD1 abnormality and compared with age-sex matched controls. We used microarrays to detect differentially expressed genes in Sotos syndrome patients and performed a global test with the aim to map NSD1 within a signaling transduction pathway. Dermal fibroblasts were obtained from nine Sotos syndrome patients and nine controls. Since NSD1 is a co-factor of the retinoic acid receptor, cultures were performed both in the presence and absence of retinoic acid.
Project description:We compared the DNA methylation patterns in blood from individuals with two rare neurodevelopmental disorders (Childhood-onset dystonia (DYT-KMT2B) and Kabuki syndrome) and healthy control samples
Project description:CHARGE syndrome is caused by heterozygous mutations in a chromatin remodeler CHD7 and characterized by a set of malformations historically postulated to arise from defects in the neural crest formation during embryogenesis. To better delineate neural crest defects in CHARGE syndrome, we generated induced pluripotent stem cells (iPSCs) from two patients with typical syndrome manifestations, and characterized neural crest cells differentiated in vitro from these iPSCs (iPSC-NCCs). We found that expression of genes associated with cell migration was altered in CHARGE iPSC-NCCs as compared to control iPSC-NCCs. Consistently, CHARGE iPSC-NCCs showed defective delamination, migration and motility in vitro, and their transplantation in ovo revealed overall defective migratory activity in the chick embryo. Altogether, our results support the historical inference that CHARGE syndrome patients have defects in neural crest migration and provide the first successful application of patient-derived iPSCs in modeling craniofacial disorders.
Project description:Genome-wide expression studies were performed on dermal fibroblasts from Sotos syndrome patients with a confirmed NSD1 abnormality and compared with age-sex matched controls. We used microarrays to detect differentially expressed genes in Sotos syndrome patients and performed a global test with the aim to map NSD1 within a signaling transduction pathway.
Project description:Kabuki syndrome (KS) is a rare multiple congenital anomalies/mental retardation (MCA/MR) syndrome described in 19811,2. In 2010, exome sequencing identified MLL2 mutations in patients with KS3. Since then, 5 studies identified a mutation in MLL2 in 56-75,6% of KS patients3-7. Here, we describe 2 KS and 1 KS-like patient with a de novo partial or complete deletion of UTX, a histone demethylase interacting with MLL2 in gene regulation. UTX locates on the X chromosome and we showed that the X chromosome with the deleted copy of UTX is preferentially inactivated despite the fact that UTX escapes X-inactivation. This study unveiled deletion of UTX as a second cause of KS and highlights the growing role of histone methylase/demethylase in MCA/MR syndrome. Two patients were analysed by Agilent array CGH 244K (AMADID: 014693) Three patients DNA were analyzed by CGH on custom targeted array 44K (AMADID: 032482). Two of them were initially analyzed using 244K Whole genome Arrays (AMADID: 014693). One third patient was selected given suspicion of deletion in one of the targeted gene (KDM6A) as amplification of some exons performed in our lab to sequence this gene failed.