Analyses of the genetic defects causing X-linked nephrogenic diabetes insipidus and intellectual disability in 2 dizygotic twin brothers revealed continuous deletions extending to intron 7 of the ARHGAP4 gene, with dysmorphic facial features having been observed in 1 of the twins.[13] The expression of TRIM25, which interacts with ARHGAP4, can induce adipocyte differentiation during adipogenesis. The gene discussed is TRIM25; the disease is nephrogenic diabetes insipidus.