ATP-binding cassette transporter sub-family C member 11, also MRP8 (Multidrug Resistance-Related Protein 8) is a membrane transporter that exports certain molecules from inside a cell. It is a protein that in humans is encoded by gene ABCC11. The gene is responsible for determination of human cerumen type (wet or dry ear wax) and presence of underarm osmidrosis (odor associated with sweat caused by excessive apocrine secretion). Function The protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). The ABCC11 transporter is a member of the MRP subfamily which is involved in multi-drug resistance. The product of this gene participates in physiological processes involving bile acids, conjugated steroids, and cyclic nucleotides. In addition, a single nucleotide polymorphism (SNP) in this gene is responsible for determination of human earwax type and presence of underarm odour. This gene and family member ABCC12 are determined to be derived by duplication and are both localized to chromosome 16q12.1. Multiple alternatively spliced transcript variants have been described for this gene. Molecular genetics The ABCC11 gene is present in the human genome as two alleles, differing in one nucleotide also known as a single nucleotide polymorphism (SNP). A SNP in the ABCC11 gene on chromosome 16 at base position 538 of either a guanine or adenine determines two distinct groups of phenotypes. These respectively code for glycine and arginine in the gene's protein product. Dominant inheritance of the GG or GA genotype is observed while the AA genotype is recessive. The phenotypes expressed by the genotypes include cerumen type (wet or dry ear wax), osmidrosis (odor associated with sweat caused by excessive apocrine secretion), and possibly breast cancer risk, although there is ongoing debate on whether there is a real correlation of the wet ear wax phenotype to breast cancer susceptibility. The GG or GA genotype produces the wet ear wax phenotype (sticky and brown colored) and acrid sweat odor and is the dominant allele. Note this phenotype requires only the presence of one guanine. The homozygous recessive AA genotype produces the dry ear wax phenotype (dry and flaky) and mildly odored sweat. The alleles containing a guanine produce a protein that is glycosylated but alleles containing an adenine are not glycosylated. The resulting protein