THE TABBY PHENOTYPE IS CAUSED BY MUTATION IN A MOUSE HOMOLOG OF THE EDA GENE THAT REVEALS NOVEL MOUSE AND HUMAN EXONS AND ENCODES A PROTEIN(ECTODYSPLASIN-A) WITH COLLAGENOUS DOMAINS

Mouse Tabby (Ta) and X chromosome-linked human EDA share the features of hypoplastic hair, teeth, and eccrine sweat glands, We have cloned t he Ta gene and find it to be homologous to the EDA gene. The gene is a ltered in two Ta alleles with a point mutation or a deletion. The gene is expressed in developing teeth and epidermis; no expression is seen in corresponding tissues from Ta mice. Ta and EDA genes both encode a lternatively spliced forms; novel exons now extend the 3' end of the E DA gene. All transcripts recovered have the same 5' exon. The longest Ta cDNA encodes a 391-residue transmembrane protein, ectodysplasin-A c ontaining 19 Gly-Xaa-Yaa repeats. The isoforms of ectodysplasin-A may correlate with differential roles during embryonic development.