Periodic Severe Angioedema without Exogenous Hormone Exposure.

Area of Science:

• Immunology
• Genetics
• Dermatology

Background:

• Hereditary angioedema (HAE) presents with recurrent swelling due to bradykinin dysregulation, unresponsive to standard treatments.
• HAE types 1 and 2 involve C1 inhibitor (C1-INH) deficiency or dysfunction, respectively.
• HAE type 3, a less common form, has normal C1-INH levels and function.

Purpose of the Study:

• To report a case of HAE type 3 in a 15-year-old female.
• To highlight the genetic basis and clinical presentation of HAE type 3.
• To discuss potential therapeutic implications for HAE type 3.

Main Methods:

• Case report of a 15-year-old female with recurrent angioedema.
• Comprehensive complement studies including C4, C1q, and C1-INH (quantitative and qualitative).
• Genetic analysis to identify mutations in relevant genes, specifically Factor XII.

Main Results:

• The patient experienced frequent, prolonged angioedema attacks, exacerbated by hormonal medication.
• All complement studies, including C1-INH levels and function, were within normal limits.
• Genetic testing revealed a mutation in exon 9 of the Factor XII gene, confirming HAE type 3.

Conclusions:

• HAE type 3 is characterized by normal C1-INH and is associated with Factor XII mutations.
• This HAE subtype is more prevalent in women and may be influenced by estrogen levels.
• Hormonal manipulation strategies, such as progesterone, may be effective treatments for HAE type 3.