Abstract: Methods of treating congenital muscular dystrophy in a mammal, one of which comprises administering to the mammal a therapeutically effective amount of a protein comprising at least one binding domain for a laminin and at least one binding domain for &agr;-dystroglycan, and the other of which comprises administering to the mammal a therapeutically effective amount of a substance that upregulates endogenous agrin, an isolated and purified non-naturally occurring protein or polypeptide comprising at least one binding domain for a laminin and at least one binding domain for &agr;-dystroglycan, an isolated and purified nucleic acid encoding the protein or polypeptide, optionally in the form of a recombinant vector, a composition comprising (i) the aforementioned protein or polypeptide or nucleic acid and (ii) a pharmaceutically acceptable carrier, a nonhuman transgenic animal, which expresses the aforementioned protein or polypeptide or comprises and expresses the aforementioned nucleic acid, and a method of iden