Fig. 1: Southern blot using EcoRI and EagI digestion, probed with StB12.3, using extended electrophoresis to illustrate several subtle specimen types.

1: Normal female. 2: Full-mutation male; note the combination of a predominant band with a diffuse smear. 3: Female with 28 and 52 repeats, with the smaller allele predominantly active. 4: Female with 26 and 52 repeats, with the larger allele predominantly active. 5: Female with 18 and ~80 repeats, with equal X-inactivation. 6: Normal male. 7: Normal male, underloaded due to DNA degradation (the apparent line between lanes 6 and 7 is a photographic artifact). 8: Normal female. 9: Normal male. 10: Normal male. 11: Affected male, underloaded and very diffuse. 12: Premutation male. 13: Female with 20 and 70 repeats, with the smaller allele virtually exclusively active (the only evidence of abnormality is the slow migration of the “5.2 kb” band). 14: Female with 27 and 42 repeats, with the larger allele somewhat more active. 15–17: Unremarkable normal females and male. Figure provided by Genetics & IVF Institute. Reprinted from Maddalena et al.²