The present invention concerns a pharmaceutical composition comprising a pharmaceutically acceptable carrier and a compound selected in the group comprising (i) a polypeptide comprising an amino acid sequence selected in the group comprising the amino acid sequence of the long isoform in Homo sapiens of the RdCVF2 gene (SEQ ID NO: 10), orthologs, derivatives and fragments thereof, (ii) a polynucleotide coding for said polypeptide, (iii) a vector comprising said polynucleotide, and (iv) a host cell genetically engineered expressing said polypeptide; the use of such a composition for the manufacture of a medicament for treating and/or preventing a neurodegenerative disorder in a subject; and a method of testing a subject thought to have or be predisposed to having a neurodegenerative disorder.