Hereditary Angioedema (HAE)
Description
Hereditary Angioedema (HAE) is a rare genetic disorder that causes episodes of swelling, primarily in the face, hands, feet, and abdomen. This swelling is caused by a deficiency or dysfunction of a protein called C1 esterase inhibitor, which regulates the immune system. While HAE can be challenging to manage, understanding the condition and its treatments can empower individuals to live full and active lives. This blog will delve into the details of HAE, covering its causes, symptoms, diagnosis, and available treatment options.
Genes Involved
HAE is caused by mutations in the SERPING1 gene, which codes for C1 esterase inhibitor. There are two main types of HAE:
- Type 1 HAE: This type is characterized by a deficiency in C1 esterase inhibitor levels.
- Type 2 HAE: This type is characterized by a dysfunctional C1 esterase inhibitor, even if the levels are normal.
Recognizing the Signs and Symptoms
HAE episodes can vary in severity and frequency, but typically involve:
- Sudden swelling: The most common symptom, often occurring in the face, hands, feet, genitals, and abdomen.
- Pain: The swelling may be accompanied by pain, particularly in the abdomen.
- Gastrointestinal issues: Abdominal swelling can lead to nausea, vomiting, diarrhea, and constipation.
- Respiratory problems: Swelling in the throat can cause difficulty breathing, a life-threatening complication.
- Other symptoms: Less common symptoms may include swelling of the eyes, lips, tongue, and larynx.
Causes
HAE is caused by an inherited gene mutation in the SERPING1 gene. This mutation leads to either a deficiency in C1 esterase inhibitor or a dysfunctional protein. The mutation can be inherited from one or both parents. If one parent carries the gene, their children have a 50% chance of inheriting the mutation. If both parents carry the gene, their children have a 75% chance of inheriting the mutation.
Inheritance/recurrence risk
HAE is an autosomal dominant disorder, meaning that a person only needs to inherit one copy of the mutated gene from either parent to develop the condition. The risk of inheritance depends on the carrier status of the parents. If one parent carries the mutated gene, their children have a 50% chance of inheriting the mutation. If both parents carry the mutated gene, their children have a 75% chance of inheriting the mutation.
