Did you know?
The occurrence of Hereditary Angioedema is approximately 1:50,000 people.
There are three types.
Type I is the most common, at approximately 83%, and is characterized in the bloodwork by little to no amount of C1-Esterase Inhibitor in the blood.
Type II is the second most common at approximately 16% and is characterized by a normal amount of C1-Esterase Inhibitor in the blood but little to no function of that complement.
Type III is the least common, is found in <1%, is most prevalent in women, and is not always clear in the bloodwork (which can be nonexistent sometimes and look normal other times), but responds the same way to blood products containing functional C1-Esterase Inhibitor. Attacks are often exacerbated by estrogen.
Although there are slight differences in each type, the severity, frequency, and location of attacks can be the same. That means that people with Type III are just as likely to have laryngeal swelling as Type I patients.
These are autosomal dominant conditions, so can be passed down by either or both parents, but Type III can also occur as a mutation. It can be mild to the extent of seeming nonexistent in some people and be severe in someone else.
Type III has a direct correlation with a mutation in Factor VII, which has other implications.
It has been connected (although not yet well understood) with mutations in Factor H, which can lead to Early Onset Macular Degeneration (which is extremely rare).
And just a little extra tidbit of strangeness, when I was diagnosed with Macular Degeneration at 21, my Ophthalmologists had never previously seen someone with the disease at my age. There is such a thing as Juvenile Macular Degeneration which affects very young children - which is tragic.
The 'funny' part is that my father-in-law-to-be was also diagnosed with Early Onset Macular Degeneration in his 20s - just considering how rare it is.