Disorders of sexual development (DSDs) often result from defects in the process of primary sex determination and/or establishment of steroidogenesis in the bipotential gonad. The gonad primordium is initially balanced between testis and ovarian fates by antagonistic signals. In XY embryos, this balance is disrupted by expression of Sry, which activates genes that promote the testis and oppose the ovarian pathways. While roles for a few genes have been defined by mutation, >50% of human DSD cases are unexplained by known genes, and likely involve unknown players in the sex determination network. In a pilot study, we measured expression levels in an intercross F2 (B6 x 12981) panel and conducted a first order conditional independence analysis. This work defined a male and female sub-network, and suggested critical nodes In the connectivity map among the 54 genes in our study. To expand this analysis, we plan to conduct RNAseq on sorted XX and XY supporting and steroidogenic cell precursors at eight timepoints between E11.5-E13.5, the period when primary sex determination occurs. To define the temporal relationship between genes, we will train a Hidden Markov model on this dataset to identify genes that are activated or repressed in sequential cascades during initiation of the male or female pathways. We will integrate results with DNasel hypersensitivity maps of El 3.5 XX and XY supporting and steroidogenic cell precursors to predict interactions between transcription factors and downstream regulatory regions. Key predictions will be tested using ChIP and gain and loss of function approaches. We will then use this information to target exome sequencing of human DSD patients in non-coding regions of genes that we identify as key regulators of sexual development. Subsequently, we will validate these findings using physiologically relevant transient reporter assays. This novel approach will establish a new paradigm to predict the proximate effects of allelic variants on the sex determination network, and use this data to inform the iterative ranking of allelic variants identified in human DSD patients based on their likelihood of causation. This work will lead immediately to improvements in diagnosis, clinical assessment, and treatment decisions for DSD patients.
This is a novel approach to evaluate and prioritize allelic variants detected in a targeted sequencing approach of genomic regions involved in transcriptional networks underlying DSDs. Using global information about the temporal transcriptional architecture underlying sex determination, combined with data that defines cis regulatory elements, we will use our transcriptional framework and transient reporter assays to rank allelic variants and inform causality of alleles identified in human DSDs.
|Sanna-Cherchi, Simone; Khan, Kamal; Westland, Rik et al. (2017) Exome-wide Association Study Identifies GREB1L Mutations in Congenital Kidney Malformations. Am J Hum Genet 101:789-802|
|Lopez-Rivera, Esther; Liu, Yangfan P; Verbitsky, Miguel et al. (2017) Genetic Drivers of Kidney Defects in the DiGeorge Syndrome. N Engl J Med 376:742-754|
|Frosk, Patrick; Arts, Heleen H; Philippe, Julien et al. (2017) A truncating mutation in CEP55 is the likely cause of MARCH, a novel syndrome affecting neuronal mitosis. J Med Genet 54:490-501|
|Shaw, Natalie D; Brand, Harrison; Kupchinsky, Zachary A et al. (2017) SMCHD1 mutations associated with a rare muscular dystrophy can also cause isolated arhinia and Bosma arhinia microphthalmia syndrome. Nat Genet 49:238-248|
|Ta-Shma, Asaf; Khan, Tahir N; Vivante, Asaf et al. (2017) Mutations in TMEM260 Cause a Pediatric Neurodevelopmental, Cardiac, and Renal Syndrome. Am J Hum Genet 100:666-675|
|Ozantürk, Ay?egül; Davis, Erica E; Sabo, Aniko et al. (2016) A t(5;16) translocation is the likely driver of a syndrome with ambiguous genitalia, facial dysmorphism, intellectual disability, and speech delay. Cold Spring Harb Mol Case Stud 2:a000703|
|Bolar, Nikhita Ajit; Golzio, Christelle; Živná, Martina et al. (2016) Heterozygous Loss-of-Function SEC61A1 Mutations Cause Autosomal-Dominant Tubulo-Interstitial and Glomerulocystic Kidney Disease with Anemia. Am J Hum Genet 99:174-87|
|Lindstrand, Anna; Frangakis, Stephan; Carvalho, Claudia M B et al. (2016) Copy-Number Variation Contributes to the Mutational Load of Bardet-Biedl Syndrome. Am J Hum Genet 99:318-36|
|Katsanis, Nicholas (2016) The continuum of causality in human genetic disorders. Genome Biol 17:233|
|Jordan, Daniel M; Frangakis, Stephan G; Golzio, Christelle et al. (2015) Identification of cis-suppression of human disease mutations by comparative genomics. Nature 524:225-9|
Showing the most recent 10 out of 30 publications