HRG4 unc-119 lipid binding chaperone http://identifiers.org/mgd/MGI:1328357 protein coding gene Unc119 Gene HRG4|Rg4|UNC119|MRG4|Rtg4|Unc119h MGI:1328357 + UNC119 Rtg4 genetic mapping MRG4 O Rg4 Unc119h