This is the second part of our series about the condition based on our patient booklet “Fast Facts for Patients: Thrombotic Thrombocytopenic Purpura”. This article details the types and symptoms of TTP.
Types of TTP
Although there is often no clear trigger of TTP, it can occur after an infection and also in pregnancy. You cannot “catch” TTP from someone else who has it. There are two types of TTP, relating to the reason why a person no longer has ADAMTS13. The most common type is iTTP; cTTP is much rarer.
Immune TTP (iTTP)
iTTP is caused when a person’s immune system starts to produce antibodies against ADAMTS13 that remove it from the plasma. It cannot be passed onto someone else. Older terms for iTTP that you may come across are “idiopathic” or “acquired” TTP.
Congenital TTP (cTTP)
Rarely, TTP is caused by a genetic condition. The production of ADAMTS13 is controlled by a gene called ADAMTS13, which is found on chromosome 9. cTTP occurs when mutations (errors in the “genetic code” – the nucleotide sequence – for ADAMTS13) are inherited, which mean that the body does not make enough ADAMTS13. cTTP can be diagnosed shortly after birth or in childhood, but sometimes is not diagnosed until much later in life, even adulthood (such as during pregnancy).
The sequence of molecules that make up a protein depends on the sequence of nucleotides in the gene that codes for it. If the nucleotide sequence becomes altered (mutated), the resulting protein may not work properly or may no longer be made, which can cause problems (diseases).
How Is cTTP Inherited?
Everyone inherits two copies of the ADAMTS13 gene, one from each of their parents. To inherit cTTP, you have to inherit two non-working copies of the ADAMTS13 gene. This is called an autosomal recessive disease.
Symptoms of TTP
TTP symptoms can vary from person to person, depending on how the body is affected by the disease. iTTP symptoms usually appear quickly (over a few weeks), whereas cTTP symptoms may appear more slowly.
Common symptoms include:
- neurological symptoms caused by small blood clots affecting the brain, such as headache, confusion, and weakness/abnormal sensation and/or seizures.
Other symptoms can include:
- abdominal or chest pain
- breathlessness (due to anemia)
- dark urine
- bruising and small bleeds under the skin, which look like small red dots, that are called petechiae (pronounced “puh-TEE-kee-eye”) and caused by low platelet levels.
Although symptoms often improve dramatically with treatment, fatigue can persist for several months or longer after an acute TTP episode. Problems with low mood (such as depression) and memory or concentration can occur.
Information based on Fast Facts for Patients: Thrombotic Thrombocytopenic Purpura (Karger, 2022).