ADAMTS13 mutations and SNPs in 10 patients with pregnancy-onset USS. Shown are the location and number of affected patients. Ten distinct mutations of ADAMTS13 gene (indicated in black boxes) were found. Five mutations were located in the N-terminal part of ADAMTS13, 4 of them within the metalloprotease domain (In7/Ex8p: c.825-10_843del29, p.Val88Leu, p.Ala95Pro, and p.Gly236Cys) and 1 within the spacer domain (p.Ala631Val). Five mutations were located in the C-terminal part of ADAMTS13, 1 within the third TSP-1 domain (p.Cys758Arg), 2 within the fourth TSP-1 domain (c.2455delG p.Ala819LeufsX24 and p.Glu812X), 1 within the seventh TSP-1 domain (p.Arg1060Trp), and 1 within the 8 TSP-1 domain (p.Gln1105X). Six miscellaneous SNPs of the ADAMTS13 gene (indicated in white boxes) were also found. Three SNPs were located in the N-terminal part of ADAMTS13 within the signal peptide (p.Arg7Trp), the cysteine-rich domain (p.Gln448Glu), or the spacer domain (p.Pro618Ala). Three other SNP were located in the C-terminal part of ADAMTS13 in the second TSP-1 domain (p.Ala732Val), the fifth TSP-1 domain (p.Ala900Val), or the seventh TSP-1 domain (p.Ala1033Thr). The number of patients affected by each mutation (black histograms) and each SNP (white histograms) are presented at the bottom of the figure. Interestingly, the mutation p.Arg1060Trp, the SNP p.Arg7Trp, and the SNP p.Ala1033Thr (systematically associated) were present in 8 of 10 patients and therefore constituted a cluster of ADAMTS13 genetic variants. The 9 other mutations were present only in single patients. The SNP p.Gln448Glu was the second most frequent SNP, present in 7 patients.