Other molecular mechanisms include the involvement of a second mutation in F8 gene (homozygous or compound heterozygous), the presence of a second hemostatic defect due to mutations in genes other than F8 gene (e.g., von Willebrand factor, VWF), abnormalities of the X-chromosome in structure and number (e.g., Turner syndrome), and androgen insensitivity syndrome (Janczar et al., 2020; Miller and Bean, 2020; Shen et al., 2022). This evidence concerns the gene VWF and Turner syndrome.