De novo variants disrupt an LDB1-regulated transcriptional network in congenital ventriculomegaly

Congenital hydrocephalus (CH), characterized by cerebral ventriculomegaly (CV), is among the most common and least understood pediatric neurosurgical disorders. We have identified in the largest-assembled CV cohort (>2,697 parent-proband trios) an exome-wide significant enrichment of protein-altering de novo variants (DNVs) in LDB1 (p = 1.11 x 10-15). Eight unrelated patients with ventriculomegaly, developmental delay, and dysmorphic features harbored loss-of-function DNVs that truncate LDB1’s carboxy-terminal LIM interaction domain, which regulates assembly of LIM homeodomain-containing transcriptional modulators. Integrative multiomic analyses suggest LDB1 is a key transcriptional regulator in ventricular neuroprogenitors through it’s binding to LIM-homeodomain proteins, including SMARCC1 and ARID1B. Indeed, LIM-homeodomain-containing genes carry a disproportionate burden of protein-damaging DNVs in our cohort, with SMARCC1 (p = 5.83 x 10-9) and ARID1B (p = 1.80 x 10-17) surpassing exome-wide significance thresholds. These data identify LBD1 as a novel neurodevelopmental disorder gene and suggest an LDB1-regulated transcriptional program is essential for human brain morphogenesis.