Figure 1: (a) Electrophoresis of the PCR products on a 5% agarose gel. Lane 6 (44 CGG repeats) and lane 8 (49 CGG repeats) serve as the controls. Lanes 2, 3, and 4 show two normal alleles. Lanes 1, 5, and 7 show single alleles that can be alternatively explained by homozygotes or one normal allele plus an unamplified premutation allele. (b) Capillary electrophoresis of subject P033 [lane 2 in Figure 1a] shows two normal alleles with only one CGG repeat difference. (c) The previously reported method using FRAXSOFT analysis software incorrectly shows a homozygote in subject P033.