This mutation was identified in a screen of progeny of ENU-treated mice for aberrant signal transduction through toll-like receptors (TLR). It substitutes G for A in the 9th of 11 exons, replacing a highly-conserved histidine with a positively-charged arginine at amino acid 412 (H412R), which resides in the ninth of 12 predicted transmembrane domains. (J:86521, J:105484) Additional incidental mutations were detected in sequencing for the causative mutation, Unc93b13d, and may be present in stocks carrying this mutation.