1. 3’ dTP-PCR 5’ dTP-PCR -dF/dT -dF/dT 90 °C 85 °C FM male 100-300 rpts FM male 600-1000 rpts FM male 650 rpts FM male 250-1200 rpts FM female 29 / >200 rpts FM female 20 / >200 rpts FM female 24 / 400 rpts FM female 29 / 600 rpts FM female 29 / 330 rpts 70 72 74 76 78 80 82 84 86 88 90 92 94 70 72 74 76 78 80 82 84 86 88 90 92 94 Temperature (°C) Temperature (°C) Supplemental Figure 4: Melt peak profiles of 5’ (left) and 3’ dTP-PCR (right) products from 9 FM individuals among 44 clinical samples used for the blinded validation study. Tm cut-offs are represented by the vertical dotted lines. Repeat lengths indicated on the left were derived from earlier PCR and/or Southern blot analyses (X-axis, temperature in °C; y-axis, -dF/dT or negative first derivative of fluorescence vs temperature).