C9orf72 expansion size as determined by long-read sequencing. (A) A histogram is displayed showing the expansion size of all 814 expanded reads obtained using No-Amp sequencing for C9orf72 expansion carriers included in this study (n = 28). The number of repeats ranges from approximately 500 to 3500. The dashed grey line denotes the median (1261 repeats) of the expansion size estimates for each individual. (B) A significant correlation exists between the number of repeats as measured by No-Amp sequencing and Southern blotting. Each C9orf72 expansion carrier is symbolized by a filled circle; the colour is an indication of the number of reads for a given individual [from low (dark blue) to high (dark red)]. The solid grey line denotes the linear regression line. (C) The expansion size determined by No-Amp sequencing (light blue) is compared to that determined by Southern blotting (dark blue). (D) When using the median expansion size as a cut-off point, smaller expansions (light blue) appear to be associated with a higher number of reads as compared to longer expansions (dark blue). For each box plot, the median is represented by a solid black line, each box spans the interquartile range (IQR; 25th percentile to 75th percentile), and every individual is visualized as a filled circle.