Figure 1.

HhaI Assay

(A) A schematic presentation of the genomic region around the G₄C₂ repeat. Two predicted CpG islands located in the sequences flanking the repeat were covered by three fragments.

(B) DNA undigested and digested with HhaI was amplified for all three fragments and the resulting band intensity quantified. Only fragment #1 shows differential methylation between expansion carriers and noncarriers.

(C) Samples with intermediate size alleles (24–43 repeats) were not methylated upstream of the G₄C₂ repeat (fragment #1).

(D) Representative gel analysis of 12 ALS expansion carriers, 12 ALS noncarriers, and 12 controls (a higher methylation level was observed in expansion carriers versus noncarriers).