Fig. 2: Characterisation of the two FGF14 structural variants identified in families 1 and 2.

A UCSC schematic (GRCh37, hg19) showing ITGBL1 and FGF14. The blue bar indicates the region spanned by the duplication (family 1); the thicker region of the bar shows the minimum duplicated interval. The red bar indicates the region spanned by the deletion (family 2). B Sequence chromatogram showing the breakpoints of the deletion identified in family 2. The deleted region overlaps with 4/4 ITGBL1 isoforms (including exons 8–11 in isoform 1, exons 7–10 in isoforms 2 and 3, and exons 7–11 in isoform 4) and the last two exons of FGF14-1A/1B. The 5′ boundary maps to an intronic region of ITGBL1, 114 bp from the nearest exon. The 3′ boundary maps to FGF14 intron 3. The sequence GTTT is present at both ends of the CNV and therefore cannot be definitively ascribed to either side of the breakpoint. C Schematic of the two FGF14 isoforms 1A and 1B indicating the location of structural and sequence variants identified in this study or previously reported in cases with SCA27/EA (see Supplemental Material for references). Sequence variants refer to FGF14-1B (NM_175929). Horizontal lines indicate the FGF14 exons affected by structural variants. Arrows indicate variants extending to genes adjacent to FGF14, dashed bars indicate the exons affected by the maximum coordinates of the CNV. Note that the bars do not indicate the position of the breakpoints.