Disclosed herein are novel nucleic acid and protein sequences that are essential to fertility. In particular, human Mater cDNA and protein sequences are provided. Functional MATER is required for female fertility; zygotes that arise from Mater null oocytes do not progress beyond the two-cell stage. Methods are described for detecting an autoimmune response to MATER in a subject by detecting autoantibodies that recognize an epitope of a MATER protein. Also provided are methods for diagnosis of infertility or reduced fertility by detecting presence of MATER protein autoantibodies in a subject. The disclosure also describes kits for detecting MATER autoantibodies comprising MATER protein.