Hereditary alpha tryptasemia syndrome

Hereditary Alpha Tryptasemia Syndrome or hereditary α-tryptasemia syndrome or HATS is a genetic and multi-systemic disease caused by an increased copy number α-tryptase-encoding regions on the TPSAB1 (TPSAB1) gene.

Hereditary alpha tryptasemia/familial hypertryptasemia
Hereditary alpha tryptasemia (H⍺T or HAT), alternatively known as familial hypertryptasemia (FHT), is common in the general population, affecting around 1 in 20 people, and is often asymptomatic.

Hereditary alpha tryptasemia syndrome (HATS) is only diagnosed when a cluster of associated symptoms are also present.

Signs and symptoms
Hereditary Alpha Tryptasemia Syndrome symptoms include:
 * a high baseline tryp­tase level (over 8 μg/L or over 11μg/L, depending on the criteria used)
 * positive tilt table test/dysautonomia e.g. postural orthostatic tachycardia syndrome (POTS)
 * chronic gastroesophageal reflux disease (GERD)
 * flushing/pruritus
 * Gastrointestinal dysmotility, bloating, abdominal pain, diarrhea and/or constipation, which may be diagnosed as irritable bowel syndrome (IBS) and may meet the Rome III criteria
 * chronic pain or joint pains
 * Ehlers-Danlos syndrome or hereditary skeletal abnormality
 * other connective tissue problems e.g. joint hypermobility or scoliosis
 * urticaria (hives) or skin itching
 * cardiac symptoms such as a racing or pounding heart, blood pressure swings sometimes with fainting
 * anxiety, panic attacks, or depression
 * retained primary dentition (retained baby teeth)
 * systemic venom reaction, e.g. serious bee sting allergy

The TPSAB1 has also been implicated in unexplained gastrointestinal symptoms and mast cell activation.

Learn more

 * Hereditary Alpha Tryptasemia and Hereditary Alpha Tryptasemia Syndrome: FAQ - National Institute of Allergy and Infectious Diseases