Molecular analysis of multiple genetic variants in Spanish FXII-deficient families.

We studied 3 Spanish patients with <1% FXII levels. DNA sequencing of the whole F12 gene identified 15 genetic variants. Molecular analyses of F12 mRNA demonstrated that the deficiency was caused by 5281delG in exon 9 of Patient 1 (in the homozygous state) and the 6306delG in exon 12 and another deletion of 23 bp in intron 8 of Patient 2 (both in the heterozygous state). Finally, a G-8C transversion was found in the homozygous state in Patient 3. Based on previous data, including a mouse model, the G-8C might be responsible for the FXII deficiency. None of these variants were present in 40 controls.