ANALYSIS OF MUTATIONS AND CHROMOSOMAL LOCALIZATION OF THE GENE ENCODING RFX5, A NOVEL TRANSCRIPTION FACTOR AFFECTED IN MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-II DEFICIENCY

MHC class II deficiency is a severe primary immunodeficiency character ised by the absence of major histocompatibility complex class II (MHC- II) gene expression. It is genetically heterogeneous and can result fr om defects in at least four different trans-acting regulatory genes re quired for transcription of MHC-II genes. One of these genes has recen tly been shown to encode a novel DNA binding protein called RFX5, whic h is one subunit of a heteromeric protein complex (RFX) that binds to the promoters of MHC-II genes. We have characterised the mutations in all four patients known to harbour a defect in the RFX5 gene and have mapped this new human disease gene to chromosome 1 band q21, a region frequently exhibiting chromosomal aberrations in a variety of preneopl astic and neoplastic diseases. (C) 1997 Wiley-Liss, Inc.