Table S2.
Steps of whole-exome sequencing and pathogenesis analysis
| Step | WES analysis | Result | Note |
| 1 | Total nonsynonymous SNV/indel in patients | 37,239/2,358 | |
| 2 | SNV/indel shared by all patients | 5,526/322 | |
| 3 | SNV/indel shared by all patients (after filtering SNV/indel in normal family members) | 260/20 | |
| 4 | Novel SNV/indel (after filtering known SNVs/indel from three major databases) | 17/6 | |
| 5 | Deleterious SNV/ indel (after filtering nonpathogenic SNV/ indel by three commonly used programs (SIFT, PolyPhen-2, and MutationTaster) | 6/0 | Indels are nonframeshift |
| 6 | Determine candidate gene by comprehensive analysis | Mutation in SLC26A2 | |
| 7 | Sanger sequencing validation | Confirmed | |
| 8 | SLC26A2 expression analysis in developing lumbar | Identified | |
| 9 | Functional analysis: sulfate uptake | Decreased | |
| 10 | Gene–disease network analysis | Proposed |
All synonymous SNVs were removed. Nonsynonymous SNVs include exonic nonsynonymous, stop-gain/stop-loss, readthrough, and splicing variants. Details of the six deleterious SNVs are provided in Table S3.