Treatment for hereditary angioedema with normal C1-INH and specific mutations in the F12 gene (HAE-FXII)

Hereditary angioedema with normal C1 esterase inhibitor and mutations in the F12 gene (HAE-FXII) is associated with skin swellings, abdominal pain attacks, and the risk of asphyxiation due to upper airway obstruction. It occurs nearly exclusively in women. We report our experience treating HAE-FXII with discontinuation of potential trigger factors and drug therapies. The study included 72 patients with HAE-FXII. Potential triggers included estrogen-containing oral contraceptives (eOC), hormonal replacement therapy, or angiotensin-converting enzyme inhibitors. Drug treatment comprised plasma-derived C1 inhibitor (pdC1-INH) for acute swelling attacks and progestins, tranexamic acid, and danazol for the prevention of attacks. Discontinuation of eOC was effective in 25 (89.3%) of 28 women and led to a reduction in the number of attacks (about 90%). After ending hormonal replacement therapy, three of eight women became symptom-free. Three women with exacerbation of HAE-FXII during intake of quinapril or enalapril had no further HAE-FXII attacks after discontinuation of those drugs. Eleven women were treated with pdC1-INH for 143 facial attacks. The duration of the treated facial attacks (mean: 26.6 h; SD: 10.1 h) was significantly shorter than that of the previous 88 untreated facial attacks in the same women (mean: 64.1 h; SD: 28.0 h; P < 0.01). The mean reduction in attack frequency was 99.8% under progestins after discontinuing eOC (16 women), 93.8% under tranexamic acid (four women), and 100% under danazol (three women). For patients with HAE-FXII, various treatment options are available which completely or at least partially reduce the number or duration of attacks.

Hereditary angioedema with normal C1-INH with versus without specific F12 gene mutations

BACKGROUND

Hereditary angioedema with normal C1-INH may be linked to specific mutations in the coagulation factor 12 (FXII) gene (HAE-FXII) or mutations in genes that are still unknown (HAE-unknown). To assess the differences in transmission and inheritance, clinical features, and laboratory parameters between patients with HAE-FXII and HAE-unknown.

METHODS

Sixty-nine patients with HAE-FXII from 23 unrelated families and 196 patients with HAE-unknown from 65 unrelated families were studied.

RESULTS

Both HAE-FXII and HAE-unknown are inherited as autosomal-dominant traits with incomplete penetrance. The male to female ratio was 1 : 68 in HAE-FXII and 1 : 6.3 in HAE-unknown. The maternal to paternal transmission ratio was 35 : 14 for HAE-FXII and 109 : 12 for HAE-unknown. Mean age at onset of clinical symptoms was 20.3 years in patients with HAE-FXII and 29.6 years in patients with HAE-unknown. The incidence of asphyxiation due to angioedema was similar for HAE-FXII and HAE-unknown. Oral contraceptives and pregnancies had a significantly higher impact on HAE-FXII than on HAE-unknown. Slightly decreased C1-INH activity and C4 concentration were observed in more patients with HAE-FXII than HAE-unknown. Tests for FXI and FXII activity, plasminogen activator inhibitor 1, and activated partial thromboplastin time showed variability but no significant differences between the groups. No abnormalities were found for C1-INH protein, C1q, alpha2-macroglobulin, antithrombin III, and angiotensin-converting enzyme. In families with HAE-FXII, the number of female offspring with F12 mutations was significantly increased and that of male offspring was significantly decreased.

CONCLUSIONS

HAE-FXII and HAE-unknown differ in various respects, including gender distribution, genetics, symptoms, and estrogen impact.