Figure 2. Sequence chromatogram of the Cys86X mutation in COL2A1 exon 2. The sequence chromatogram of COL2A1 exon 2 encompassing codon 86 demonstrates the c.258C>A mutation (GenBank NM_001844.4, +1 in cDNA numbering corresponding to the A of the methionine translation initiation codon) converting a cysteine codon to a stop codon in two affected individuals while the mutation is not present in two unaffected individuals. DNA analysis of all other affected family members cosegregated with this mutation while the mutation was not present in all unaffected family individuals.