The mutation is a T to C transition at position +2 in the splice donor of intron 25, a highly conserved residue in mammalian splice sites. RT-PCR shows complete skipping of exon 25, which led to a frame shift and the introduction of a premature stop codon 36 bp into exon 26 and therefore the truncation of the protein toward the C-terminal end of the CSPG repeat elements.