Project description:<p>The ultimate purpose of this research is to identify genes causing hereditary disorders. We are scaling a new approach to identify the candidate genes and gene mutations that underlie rare human Mendelian (a set of primary tenets relating to the transmission of hereditary characteristics from parent to child) diseases by using exome (protein coding segments of DNA) resequencing.</p> <p>The exome sequences of ten unrelated individuals with a diagnosis of Kabuki Syndrome (OMIM: <a href="http://www.ncbi.nlm.nih.gov/omim/147920" target="_blank">147920</a>) were obtained by massively parallel DNA sequencing.</p>
Project description:<p>The ultimate purpose of this research is to identify genes causing hereditary disorders. We are scaling a new approach to identify the candidate genes and gene mutations that underlie rare human Mendelian (a set of primary tenets relating to the transmission of hereditary characteristics from parent to child) diseases by using exome (protein coding segments of DNA) resequencing.</p> <p>The exome sequences of ten unrelated individuals with a diagnosis of Kabuki Syndrome (OMIM: <a href="http://www.ncbi.nlm.nih.gov/omim/147920" target="_blank">147920</a>) were obtained by massively parallel DNA sequencing.</p>
Project description:Kabuki syndrome is a Mendelian intellectual disability syndrome caused by mutations in either of two genes (KMT2D and KDM6A) involved in chromatin accessibility. We previously showed that an agent that promotes chromatin opening, the histone deacetylase inhibitor (HDACi) AR-42, ameliorates the deficiency of adult neurogenesis in the granule cell layer of the dentate gyrus, and rescues hippocampal memory defects in a mouse model of Kabuki syndrome (Kmt2d+/βGeo). Unlike a drug, a dietary intervention could be quickly transitioned to the clinic. Therefore, we have explored whether treatment with a ketogenic diet could lead to a similar rescue through increased amounts of beta-hydroxybutyrate, an endogenous HDACi. Here, we report that a ketogenic diet in Kmt2d+/βGeo mice modulates H3ac and H3K4me3 in the granular cell layer, with concomitant rescue of both the neurogenesis defect and hippocampal memory abnormalities seen in Kmt2d+/βGeo mice; similar effects on neurogenesis were observed upon exogenous administration of beta-hydroxybutyrate. These data suggests that dietary modulation of epigenetic modifications through elevation of beta-hydroxybutyrate may provide a feasible strategy to treat the intellectual disability seen in Kabuki syndrome and related disorders. We used microarrays to query global gene expression changes in the hippocampus of wild type and Kmt2d+/βGeo (Kabuki syndrome model) mice on a regular diet to identify specific gene expression abnormalities in the hippocampus of the Kabuki syndrome mouse model.
Project description:<p>The NHGRI Next Generation Mendelian Genetics project uses exome resequencing to identify variants in unsolved Mendelian diseases.</p> <p>Ehlers-Danlos syndrome Type VIII is a dominantly inherited connective tissue disorder that is distinguished from other forms of EDS by significant early-onset periodontal disease. Although the clinical phenotype is well delineated, the underlying molecular basis remains unknown. By studying a large family of affected and unaffected individuals with the EDS VIII by exome sequencing, we hope to identify unique regions of homology to assist in identifying the causative gene. </p>
Project description:Growth deficiency is a characteristic feature of both Kabuki syndrome 1 (KS1) and Kabuki syndrome 2 (KS2), Mendelian disorders of the epigenetic machinery with similar phenotypes but distinct genetic etiologies. We previously described skeletal growth deficiency in a mouse model of KS1 and further established that a Kmt2d -/- chondrocyte model of KS1 exhibits precocious differentiation. Here we characterized growth deficiency in a mouse model of KS2, Kdm6a tm1d/+. We show that Kdm6a tm1d/+ mice have decreased femur and tibia length compared to controls and exhibit abnormalities in cortical and trabecular bone structure. Kdm6a tm1d/+ growth plates are also shorter, due to decreases in hypertrophic chondrocyte size and hypertrophic zone height. Given these disturbances in the growth plate, we generated Kdm6a -/- chondrogenic cell lines. Similar to our prior in vitro model of KS1, we found that Kdm6a -/- cells undergo premature, enhanced differentiation towards chondrocytes compared to Kdm6a +/+ controls. RNA-seq showed that Kdm6a -/- cells have a distinct transcriptomic profile that indicates dysregulation of cartilage development. Finally, we performed RNA-seq simultaneously on Kmt2d -/-, Kdm6a -/-, and control lines at Days 7 and 14 of differentiation. This revealed surprising resemblance in gene expression between Kmt2d -/- and Kdm6a -/- at both time points and indicates that the similarity in phenotype between KS1 and KS2 also exists at the transcriptional level.