Hereditary alpha Tryptasemia (HaT)

by | Feb 20, 2023 | Hereditary Alpha Tryptasemia | 0 comments

I was chosen to be a part of an NIH (National Institute of Health) early study on patients’ who exhibited specific symptoms: mast cell activation, Ehlers-Danlos syndrome or hypermobility and dysautonomia. I had no idea this would lead to my next diagnosis of hereditary alpha tryptasemia (HaT). HaT is a genetic trait present in about 5% of people in the U.S. and Western Europe but not all are symptomatic.

HaT is caused by an extra inherited copy of the alpha tryptase gene that leads to an elevated tryptase level in the blood. It’s autosomal dominant, meaning that if one parent has HaT, there’s a 50% chance they can pass it on to their children.

Some people with this genetic trait can be completely asymptomatic and not know they have it. But for others, their symptoms can be significant. I am one of those very symptomatic patients.The researchers at the NIH and other academic institutions have written several papers on hereditary alpha tryptasemia (HaT). A few will be included at the end.

There are some common symptoms associated with HaT: skin flushing, itching and hives; abdominal pain and bloating; connective tissue abnormalities like joint hypermobility; autonomic dysfunction and anaphylaxis to myriad of causes, but especially bees, wasps, etc.

Some of these symptoms overlap with my MCAS (mast cell activation syndrome), EDS (Ehlers Danlos syndrome), and dysautonomia. The standout symptom was the anaphylaxis. I have experienced 14 episodes of anaphylaxis. Some of those episodes were severe enough to require an ICU admission.

Due to the duplication of the tryptase gene, my tryptase level typically runs around 18-20’s. Others with HaT can have a triplication, causing their levels to be higher.

Some of the issues from HaT for me are vibration, pressure and medications. Any vibration, whether from riding in a car, plane, hand mixer, TENS unit, cause itching and hives. Pressure, even as light as sleeping with my arms across my stomach, sheet wrinkles on my skin, too tight clothing, braces not properly fitted, will also cause hives and itching. I have a long list of medication allergies, ranging from anaphylaxis to typical allergic reactions. I always make sure the first time I take any new medication, that I am not alone and have my EpiPens nearby.

On a positive note, now that I know most of my triggers, I have not had an episode of anaphylaxis in 2 years. I can manage HaT quite well and I am forever grateful to the physician researchers who have been so dedicated to studying HaT. Another important collaboration was with Gene by Gene Lab who does the testing for HaT:

Hereditary Alpha Tryptasemia: Genotyping and Associated Clinical Features.

Clinical relevance of inherited genetic differences in human tryptases:

  • Hereditary alpha-tryptasemia and beyond

If your serum tryptase is >8 and you exhibit the above symptoms, your physician can order the test from Gene by Gene genetics lab. It’s a simple cheek swab. Treatment is symptomatic at this point but the researchers are always working on ways to better manage it.

 About Author Jan Hempstead

My name is Jan Hempstead and I’m an RN, although I medically retired sooner than I would have liked because of my multiple diagnoses. I’m also a mom, wife, sister and friend.

This blog is my story about living well with Ehlers Danlos syndrome (EDS), rheumatoid arthritis (RA), mast cell activation syndrome (MCAS), chronic kidney disease (CKD), hereditary alpha tryptasemia (HaT), dysautonomia and Sjogren’s Syndrome (SS).

I started out with EDS and one by one, another diagnosis kept getting added on. Come follow me as I share my journey with multiple specialists, what has worked and has not, and where I’m going next.

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