Copy number variants (CNVs) are major contributors to genetic disorders (1). We have dissected Aregion of the 16p11.2chromosome-which encompasses 29 genes--that confers susceptibility to ...neurocognitive defects when deleted or duplicated (2,3). Over expression of each human transcript in zebrafish embryos identified KCTD13as the sole message capable of inducing the microcephaly phenotype associated with the 16p11.2 duplication (2-5), whereas suppression of the same locus yielded the macrocephalic phenotype associated with the 16p11.2 deletion (5,6), capturing the mirror phenotypes of humans. Analyses of zebrafish and mouse embryos suggest that microcephaly is caused by decreased proliferation of neuronal progenitors with concomitant increase in apoptosis in the developing brain, whereas macrocephaly arises by increased proliferation and no changes in apoptosis. A role for KCTD13 dosage changes is consistent with autism in both a recently reported family with a reduced 16p11.2 deletion and a subject reported here with a complex 16p11.2 rearrangement involving de novo structural alteration of KCTD13. Our data suggest that KCTD13is a major driver for the neurodevelopmental phenotypes associated with the 16p11.2 CNV, reinforce the idea that one or a small number of transcripts within a CNV can underpin clinical phenotypes, and offer an efficient route to identifying dosage-sensitive loci.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The 16p11.2 600kb copy number variants (CNVs) are associated with mirror phenotypes on BMI, head circumference and brain volume and represent frequent genetic lesions in autism spectrum disorders ...(ASD) and schizophrenia. Here we interrogated the transcriptome of individuals carrying reciprocal 16p11.2 CNVs. Transcript perturbations correlated with clinical endophenotypes and were enriched for genes associated with ASD, abnormalities of head size and ciliopathies. Ciliary genes expression was also perturbed in orthologous mouse models, raising the possibility that ciliary dysfunction contributes to 16p11.2 pathologies. In support of this hypothesis, we found structural ciliary defects in the CA1 hippocampal region of 16p11.2 duplication mice. Moreover, using an established zebrafish model we show genetic interaction between KCTD13, a key driver of the mirrored neuroanatomical phenotypes of the 16p11.2 CNV and ciliopathy-associated genes. Overexpression of BBS7 rescues head size and neuroanatomical defects of kctd13 morphants, while suppression or overexpression of CEP290 rescues phenotypes induced by KCTD13 under- or overexpression, respectively. Our data suggest that dysregulation of ciliopathy genes contributes to the clinical phenotypes of these CNVs.
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