CRBN, encoding a 442-amino-acid protein, is identified as a gene responsible for autosomal recessive non-syndromic intellectual disability; a nonsense mutation, p.R419X, generates a truncated CRBN lacking 24 amino acids at the C-terminal owing to the presence of a premature stop codon (Higgins et al., 2004). The gene discussed is CRBN; the disease is non-syndromic intellectual disability.