May play an important role in innate immunity by mediating a signal for the production of a neutrophil chemoattractant. Interacts with TYROBP and HCST. Expressed on CD16+ monocytes and myeloid dendritic cells. By contrast, is not expressed on lymphocytes or granulocytes. Some individuals have a mutation (NM_001324073.1:c.61+1A>G) which abolishes the intron 1 donor splice site. These persons carrying the A/A genotype shows a loss of CD300H transcripts and protein. The AA genotype occurs at high frequencies in East Asian and Northern/Western European populations, but is rare in the Yoruba (West African) population. Belongs to the CD300 family. The reference genome assembly (GRCh38.p12) represents the 'A' allele (NM_001324073.1:c.61+1A>G) which abolishes the intron 1 donor splice site leading to loss of CD300H transcripts and protein.