Abstract: The invention provides a nucleic acid coding for the CGL1 polypeptide with the SEQ ID No 1 amino acid sequence or also fragments or variants of the CGL1 polypeptide. The invention also relates to the use of a nucleic acid such as defined hereinabove for producing a nucleotide probe or primer specific for the normal cgl1 gene or the mutated cgl1 gene. Another object of the invention is also to provide methods for screening a candidate compound interacting with the CGL1 polypeptide or modulating the expression of the cgl1 gene as well as sets or kits for screening such candidate compounds.