Demonstration of the mutated sequence in affected subjects by PCR using the primers T7F1 and R1 (see text). Lane 1, 1-kB ladder marker (M); lane 2, subject II-1 (affected, see Fig 2); lane 3, subject II-2 (normal); lane 4, subject III-1 (affected); lane 5, subject III-2 (affected); lane 6, normal control. In the presence of the 29-bp deletion an additional band of 150 bp is present.