hereditary angioedema

- autosomal dominant
- mutation at C1 inhibitor gene, causing low levels of C1 esterase inhibitor
- painless, non pruritic, non pitting swelling of skin
- characterised by recurrent self limited attacks involving skin, subcutaneous tissue, upper respiratory tract, gastrointestinal tract
- reduced C1, C2 and C4 levels (reduced C4 level even between attacks), normal C3
- treatment: C1 esterase inhibitor concentrates 1000-1500 unit IV over 20-30mins, danazole (induce liver enzymes to synthesize C1 esterase inhibitor), fresh frozen plasma (potential to aggravate the condition as it replaces all the complement components, not just C1 inhibitor)