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

Congenital hydrocephalus, characterized by cerebral ventriculomegaly, is among the most common and least understood paediatric neurosurgical disorders. We have identified, in the largest assembled cerebral ventriculomegaly cohort (2697 parent-proband trios), an exome-wide significant enrichment of protein-altering de novo variants in LDB1 (P = 1.11 × 10-15). Eight unrelated patients with ventriculomegaly, developmental delay and dysmorphic features harboured loss-of-function de novo variants that truncate carboxy-terminal LIM interaction domain of LDB1, which regulates assembly of LIM homeodomain-containing transcriptional modulators. Integrative multiomic analyses suggest that LDB1 is a key transcriptional regulator in ventricular neuroprogenitors through its binding to LIM-homeodomain proteins, including SMARCC1 and ARID1B. Indeed, LIM-homeodomain-containing genes carry a disproportionate burden of protein-damaging de novo variants in our cohort, with SMARCC1 (P = 5.83 × 10-9) and ARID1B (P = 1.80 × 10-17) surpassing exome-wide significance thresholds. These data identify LBD1 as a novel neurodevelopmental disorder gene and suggest that an LDB1-regulated transcriptional programme is essential for human brain morphogenesis.