Family with Sequence Similarity 166, member C (FAM166C), is a protein encoded by the FAM166C gene. The protein FAM166C (aliases c2orf70, LOC339778) is localized in the nucleus. It has a calculated molecular weight of 23.29 kDa. It also contains DUF2475, a protein of unknown function from amino acid 19–85. The FAM166C protein is nominally expressed in the testis, stomach, and thyroid .