A point mutation in the C1-inhibitor gene causes type I hereditary angiooedema.

The polymerase chain reaction and nucleotide sequencing have been used to characterise a single base substitution (CAG → TAG) at nucleotide 16842 in the C1-inhibitor gene in the affected members of a single family with type I C1-inhibitor deficiency. This mutation creates the TAG translation termination codon, thereby truncating the C1-inhibitor C-terminus by 17 amino acids. The effects of the mutation are discussed.