Definition
Actin is an essential component of the cell, enabling it to organize its shape and contents (known as the cytoskeleton), multiply and interact with its environment.
Actinopathies with autoinflammatory manifestations are a new emerging group of autoinflammatory diseases, linked to defects in the regulation of actin cytoskeleton dynamics in cells.
Epidemiology
These are rare genetic diseases, with around 50 patients described worldwide to date.
They are cosmopolitan diseases, meaning that they are found all over the world.
These diseases most often begin at birth, and because they are so rare, diagnosis is often delayed.
There are different types of transmission to offspring, depending on the disease in question. It is therefore essential to consult a specialist to assess the risk of transmission to offspring.
Genetic
To date, mutations have been described in various genes in the autoinflammatory actinopathy family: C/EBPE, WDR1, NCKAP1L, ARPC1B, CDC42, ARPC5, DOCK11.
This list is growing every year, thanks to advances in research and genetics.
The effect of these mutations is to disorganize the cell's actin network, preventing it from functioning properly.
Clinical
These diseases usually begin after birth, in the first few years of life. Patients may present with the following symptoms, depending on the mutated gene:
-recurrent infections (known as primary immune deficiency) of varying severity.
- a reduction in the number of certain cells in the blood, particularly low platelets (known as cytopenias).
- inflammation of the skin and digestive system.
- allergic and sometimes autoimmune manifestations.
Some of these diseases can lead to severe fever flare-ups (known as macrophagic activation syndrome); others to atopy.
Diagnostic
Diagnosis of the disease is genetic, and is made by a blood test.
The referring physician may offer family members a consultation to identify other people with the disease.
There is no indication for genetic testing in people with no symptoms.
Evolution
These are severe diseases with a great deal of inflammation. They have only recently been described, and there is still little experience of their evolution and long-term risks.
To date, only one case of renal amyloidosis (AA) has been reported in a patient with a DOCK11 gene mutation.
It is therefore advisable to consult your specialist on a regular basis to ensure appropriate follow-up and monitoring.
Treatment
Patients require specialized management and regular clinical and biological follow-up to monitor inflammation in the blood.
To date, there is no cure.
Some patients may benefit from a bone marrow transplant in the case of very severe manifestations.
Patients with severe inflammatory manifestations will also require specific treatments, some of which may be prescribed orally, others by injection under the skin or by intravenous infusion.
Supportive treatments may also be required: some patients will need transfusions if platelets or red blood cells are low, while others will need specific treatments to reduce the risk of infection if they are more susceptible.