Table 1.

Somatic variants identified in SLC35A2 using NGS (exome and targeted sequencing) and confirmed with ddPCR.

Sample /specimen(s)	SLC35A2 somatic variant *	Brain DNA VAF – exome [95% CI]	Leukocyte DNA VAF – exome	Brain VAF – targeted sequencing ****[95% CI]	Leukocyte DNA VAF – targeted sequencing	Average +/− SD Brain VAF – ddPCR **** [no. replicates]
Case 1/s3	c.910T>C; p.(Ser304Pro)	3.3% (2/61) ** [0.4–11.4%]	0% (0/63)	6.5 % (40/612) [4.7–8.8%]	0.21% (1/477)***	6.2% +/− 0.6 [10]
Case 2/s1	c.339_340insCTC;p.(Leu113dup)	8.9% (4/45) [2.5–21.2%]	0% (0/34)	2.4% (6/246) [0.9–5.2%]	0% (0/393)	5.3% +/− 0.6 [8]
Case 3/s2	c.634_635del;p.(Ser212Leufs*9)	14.3% (5/35) [4.8–30.2%]	0% (0/42)	6.8% (9/133) [3.1–12.5%]	0% (0/167)	8.8% +/− 0.2 [6]
Case 4/s1	c.164G>T; p.(Arg55Leu)	52.6% (20/38) [36–69%]	0% (0/71)	50.8% (97/191) [43.8–57.8%]	0% (0/226)	54.6% +/− 0.2 [3]
Case 5/s1	c.747_757dup; p.(Ala253Glyfs*100)	18.8% (8/45) [8–32.1%]	0% (0/95)	26.5% (58/219) [20.8–34.8%]	0% (0/160)	NA

^*annotated based on NM_005660.1

^**not called using the calling algorithm but reads supporting the variant were detected

^***The one read supporting the variant could represent a sequencing artifact or very low levels of variant. No variant was detected in leukocyte or saliva DNA using ddPCR with a sensitivity to detect variant allele down to 0.1%, suggesting this one read supporting the variant is a sequencing artifact.

^****VAF as estimated by targeted sequencing varies compared to that estimated from exome sequencing. This is explained by the fact that DNA aliquots for sequencing were extracted from two different pieces of the same specimen and therefore the levels will also reflect the regional variability across the specimen.