CRBN and learning disability: However, despite its role in ubiquitination and its enriched expression in the brain, the inactivation of the CRBN gene in mice didn’t lead to any embryopathy that resembles Thalidome toxicity, but rather led to a mild learning disability that was also observed in humans with a mild type of autosomal recessive non-syndromic mental retardation due to loss of function CRBN mutations24, 54, 55.