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bioRxiv2020

Convergent and distributed effects of the schizophrenia-associated 3q29 deletion on the human neural transcriptome

The 3q29 deletion (3q29Del) confers >40-fold increased risk for schizophrenia. However, no single gene in this interval is definitively associated with disease, prompting the hypothesis that neuropsychiatric sequelae emerge upon loss of multiple functionally-connected genes. 3q29 genes are unevenly annotated and the impact of 3q29Del on the human neural transcriptome is unknown. To systematically formulate unbiased hypotheses about molecular mechanisms linking 3q29Del to neuropsychiatric illness, we conducted a systems-level network analysis of the non-pathological adult human cortical transcriptome and generated evidence-based predictions that relate 3q29 genes to novel functions and disease associations. The 21 protein-coding genes located in the interval segregated into seven clusters of highly co-expressed genes, demonstrating both convergent and distributed effects of 3q29Del across the interrogated transcriptomic landscape. Pathway analysis of these clusters indicated involvement in nervous-system functions, including synaptic signaling and organization, as well as core cellular functions, including transcriptional regulation, post-translational modifications, chromatin remodeling and mitochondrial metabolism. Top network-neighbors of 3q29 genes showed significant overlap with known schizophrenia, autism and intellectual disability-risk genes, suggesting that 3q29Del biology is relevant to idiopathic disease. Leveraging "guilt by association", we propose nine 3q29 genes, including one hub gene, as prioritized drivers of neuropsychiatric risk. These results provide testable hypotheses for experimental analysis on causal drivers and mechanisms of the largest known genetic risk factor for schizophrenia and highlight the study of normal function in non-pathological post-mortem tissue to further our understanding of psychiatric genetics, especially for rare syndromes like 3q29Del, where access to neural tissue from carriers is unavailable or limited.

genetics↗

bioRxiv2019

Systematic Description of 3q29 Duplication Syndrome Reveals New Syndromic Phenotypes: Results from the 3q29 Registry

3q29 duplication syndrome (3q29Dup) is a rare genomic disorder caused by the reciprocal duplication of the 1.6 Mb 3q29 deletion syndrome region. Case reports indicate the 3q29Dup is likely to be pathogenic, but because no systematic study of the syndrome exists, the full range of manifestations is not well-understood. To develop a better understanding of 3q29 duplication syndrome, we used the 3q29 registry (https://3q29deletion.patientcrossroads.org/) to ascertain 31 individuals with 3q29Dup, the largest cohort ever surveyed in a systematic way. For comparison, we ascertained 117 individuals with the reciprocal 3q29 deletion syndrome (3q29Del) and 64 typically developing controls. We used a custom medical and demographic questionnaire to assess physical and developmental phenotypes, and two standardized instruments, the Social Responsiveness Scale (SRS) and Achenbach Behavior Checklists (CBCL/ABCL), to assess social disability. We find that our 3q29Dup participants report a high rate of problems in the first year of life (80.6%), including feeding problems (58%), failure to gain weight (42%), hypotonia (39%), and respiratory distress (29%). In early childhood, learning problems (87.1%) and seizures (25.8%) are common. Additionally, we find a rate of self-reported ASD diagnoses (39%) similar to that previously identified in 3q29Del (29%), and the granular characteristics of social disability measured using the SRS and CBCL/ABCL are comparable between 3q29Dup and 3q29Del. This is the most comprehensive description of 3q29Dup to date. Our findings can be used to develop evidence-based strategies for early intervention and management of 3q29 duplication syndrome.

genetics↗