Carboxypeptidase-N deficiency (CPND) is an autosomal recessive disorder characterized by episodic angioedema, acute or chronic urticaria, asthma, and/or allergic hypersensitivities such as hay fever. Homozygous individuals as well as their heterozygous family members have levels of carboxypeptidase N that are below the reference range, and heterozygotes are symptomatic, albeit to a generally milder degree (Mathews et al., 1980; Vincent et al., 2024).

Hereditary angioedema is a disorder characterized by recurrent episodes of severe swelling (angioedema). The parts of the body that are most often affected by swelling are the limbs, face, intestinal tract, and airway. Minor trauma or stress may trigger an attack, but swelling often occurs without a known trigger. Episodes involving the intestinal tract cause severe abdominal pain, nausea, and vomiting. Swelling in the airway can restrict breathing and lead to life-threatening obstruction of the airway. About one-third of people with this condition develop a non-itchy rash called erythema marginatum during an attack.\n\nSymptoms of hereditary angioedema typically begin in childhood and worsen during puberty.  On average, untreated individuals have swelling episodes every 1 to 2 weeks, and most episodes last for about 3 to 4 days. The frequency and duration of attacks vary greatly among people with hereditary angioedema, even among people in the same family.\n\nHereditary angioedema is broadly divided into two types, which are distinguished by levels of a protein called C1 inhibitor (C1-INH) in the blood. These types are known as hereditary angioedema due to C1-INH deficiency and hereditary angioedema with normal C1-INH. \n\nHereditary angioedema due to C1-INH deficiency is further divided into two types: type I occurs when C1-INH levels are low, and type II occurs when the C1-INH protein is not functioning correctly. \n\n\n\nThe different types of hereditary angioedema have similar signs and symptoms. 

A form of hereditary angioedema characterized by acute edema in subcutaneous tissues, viscera and/or the upper airway.

Familial cold autoinflammatory syndrome-3 is an autosomal dominant immune disorder characterized by the development of cutaneous urticaria, erythema, and pruritus in response to cold exposure. Affected individuals have variable additional immunologic defects, including antibody deficiency, decreased numbers of B cells, defective B cells, increased susceptibility to infection, and increased risk of autoimmune disorders (summary by Ombrello et al., 2012). For a discussion of genetic heterogeneity of FCAS, see FCAS1 (120100).

Approximately 40 million people take ACE inhibitors (ACEi) to treat hypertension and cardiovascular disease. A small proportion of white patients who take ACEi (0.1-0.7%) develop angioedema (AEACEI) (Israili and Hall, 1992; Vleeming et al., 1998), a potentially life-threatening side effect characterized by swelling of the face, lips, tongue, and airway that can lead to suffocation and death if severe. ACEi-associated angioedema is 4 to 5 times more prevalent among African Americans (Brown et al., 1996; Coats, 2002). Other risk factors include female sex, smoking, immunosuppressant therapy, and seasonal allergies. The pathophysiology of ACEi-associated angioedema is thought to be related to increased circulating bradykinin, which is normally degraded by ACE. During pharmacologic ACE inhibition, bradykinin is primarily degraded by aminopeptidase P (summary by Duan et al., 2005 and Woodard-Grice et al., 2010). Aminopeptidase P is encoded by 3 genes: XPNPEP1 (602443) on chromosome 10q25, XPNPEP2 (300145) on chromosome Xq25, and XPNPEP3 (613553) on chromosome 22q13.

Hereditary angioedema-4 (HAE4) is an autosomal dominant disorder characterized by episodic subcutaneous or submucosal edema with onset usually in adulthood. Swelling most commonly involves the face and tongue, sometimes resulting in occlusion of the airway, which can cause death. The larynx, abdomen, and limbs may also be involved. Circulating C1 inhibitor (C1INH) levels and function, as well as plasminogen levels and activity, are normal. Although the disorder is autosomal dominant, there is evidence of incomplete penetrance, variable expressivity, and female predominance. The episodes may be triggered by stress, oral contraceptives, ACE inhibitors, and angiotensin II receptor blockades. The pathogenesis is believed to be due to altered plasmin function resulting in enhanced release of bradykinin. Successful clinical management has been achieved with tranexamic acid, which inhibits plasmin, and icatibant, a selective bradykinin B2 receptor (113503) antagonist (summary by Farkas et al., 2021). For a discussion of genetic heterogeneity of HAE, see 106100.

Hereditary angioedema-5 (HAE5) is an autosomal dominant disorder characterized by localized and self-limiting edema of the subcutaneous or submucosal tissue due to an episodic increase in vascular permeability. Affected individuals have onset of episodic swelling of the face, lips, hands, and abdomen in the second decade of life. Treatment with tranexamic acid may be effective in reducing the severity and frequency of the attacks (summary by Bafunno et al., 2018). For a discussion of genetic heterogeneity of hereditary angioedema, see 106100.

Hereditary angioedema-6 (HAE6) is an autosomal dominant disorder characterized by onset of episodic subcutaneous and submucosal swelling in adulthood. The face, mouth, and tongue are often affected; some patients have distal limb or abdominal edema. Levels of complement component inhibitor (C1INH; 606860) are normal (summary by Bork et al., 2019). For a discussion of genetic heterogeneity of HAE, see 106100.

Hereditary angioedema-7 (HAE7) is an autosomal dominant disorder characterized by onset of recurrent episodic swelling of the face, lips, and oral mucosa in the second decade. The disorder is due to abnormal vascular permeability (summary by Ariano et al., 2020). For a discussion of genetic heterogeneity of HAE, see 106100.

Hereditary angioedema-8 (HAE8) is an autosomal dominant disorder characterized clinically by recurrent and self-limited episodes of localized edema in various organs, including the face, tongue, larynx, and extremities. In rare cases, swelling of the tongue or larynx can lead to airway obstruction. Abdominal attacks may also occur, resulting in abdominal pain, vomiting, and diarrhea. The disorder results from enhanced vascular permeability (summary by Bork et al., 2021). For a discussion of genetic heterogeneity of HAE, see 106100.

Netherton syndrome (NETH) is a rare and severe autosomal recessive skin disorder characterized by congenital erythroderma, a specific hair-shaft abnormality, and atopic manifestations with high IgE levels. Generalized scaly erythroderma is apparent at or soon after birth and usually persists. Scalp hair is sparse and brittle with a characteristic 'bamboo' shape under light microscopic examination due to invagination of the distal part of the hair shaft to its proximal part. Atopic manifestations include eczema-like rashes, atopic dermatitis, pruritus, hay fever, angioedema, urticaria, high levels of IgE in the serum, and hypereosinophilia. Life-threatening complications are frequent during the neonatal period, including hypernatremic dehydration, hypothermia, extreme weight loss, bronchopneumonia, and sepsis. During childhood, failure to thrive is common as a result of malnutrition, metabolic disorders, chronic erythroderma, persistent cutaneous infections, or enteropathy (summary by Bitoun et al., 2002).