It is characterized by repetitive episodes of swelling, frequently of the face, lips, tongue, limbs, and genitals. Edema of the gastrointestinal mucosa typically leads to severe abdominal pain; in the upper respiratory tract, it can be life-threatening. Hereditary angioedema
Hereditary angioedema (HAE) exists in three forms, all of which are caused by a genetic mutation inherited in an autosomal dominant form. They are distinguished by the underlying genetic abnormality. Types I and II are caused by mutations in the SERPING1 gene, which result in either diminished levels of the C1-inhibitor protein (type I HAE) or dysfunctional forms of the same protein (type II HAE). Type III HAE has been linked with mutations in the F12 gene, which encodes the coagulation protein factor XII. All forms of HAE lead to abnormal activation of the complement system, and all forms can cause swelling elsewhere in the body, such as the digestive tract. If HAE involves the larynx, it can cause life-threatening asphyxiation. The pathogenesis of this disorder is suspected to be related to unopposed activation of the contact pathway by the initial generation of kallikrein and/or clotting factor XII by damaged endothelial cells. The end product of this cascade, bradykinin, is produced in large amounts and is believed to be the predominant mediator leading to increased vascular permeability and vasodilation that induces typical angioedema "attacks". Management
Allergic
In allergic angioedema, avoidance of the allergen and use of antihistamines may prevent future attacks. Cetirizine is a commonly prescribed antihistamine for angioedema.
Amish lethal microcephaly is a rare genetic disorder which is characterized by severe microcephaly (small head) from birth, brain hypoplasia (underdeveloped brain), micrognathia (small chin), irritability (at second or third month of age), seizures, problems controlling their body temperature, high levels of alpha-ketogluraic acid in their urine, and less commonly hepatomegaly (large liver). Babies with this condition typically die when they are 6 months old. This disorder was named after the Amish since, in Old Order Amish communities in Pennsylvania, it affects 1 in 500 babies, while 1 in 11 people in the same communities are unaffected carriers of the (recessive) mutation that causes the disorder, it has not been found outside this population.This disorder is caused by mutations in the SLC25A19 gene in chromosome 17q25, it follows an autosomal recessive inheritance pattern


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