A novel homozygous GTG-->GCG (Val 325-->Ala) substitution was detected in the protein C gene of a newborn causing severe purpura fulminans post partum. In the consanguineous parents and two further infants a heterozygous type 1 protein C deficiency was found. Up to now the heterozygous individuals are clinically unaffected. The mutation co-segregates with the protein C deficiency state. It creates a restriction enzyme (Sac II) cleavage site.