COL1A1 and Salla disease: In our clinical setting for the genetic diagnosis of fetal SD, the first-line of gene testing was Sanger sequencing of a gene set including FGFR3, COL1A1, COL1A2, SOX9, and DTDST. However, with the advent of NGS and the introduction of WES, the cost of sequencing all the candidate genes by Sanger sequencing already exceeds that of WES.