What is carasil?
Carasil is an abbreviation of a rare genetic disorder, where the main component involved is known as the HTRA1 gene, inherited from both parents. This gene forms a protein that reduces blood flow which impairs vessel development in the brain. With the lack of blood flow, this can damage the brain, leading to complications.1
The abbreviation for Carasil stands for:1
- Cerebral: Vessels in the brain relating to the cerebellum that control coordination and balance
- Autosomal recessive: Two copies of the gene have to be present in order for signs and development of symptoms to show
- Subcortical Infarcts: Area of the brain involved in movements, reasoning and memory. Its brain tissue dies due to a lack of blood supply and oxygen transported to the brain because of the damage to the vessels
- Leukencephalopathy: destruction of the protective layer of our brain nerve cells, mainly in the white matter of the brain.
What are the signs and symptoms of carasil?
The prevalence of Carasil is currently unknown, and patients are only diagnosed and admitted in the later stages of the disease. Most symptoms arise between the ages of 20 to 30 years old, starting with abnormalities in gait, complaints of mid or lower back pain and changes in mood.4 The main symptoms for diagnosis commonly seen are alopecia, loss of motor ability, cognitive dysfunction and strokes caused by blood clot formation.3 Almost 23% of Carasil cases develop stroke before the age of 40, where progression continues after these years, affecting emotional and physical stability. Some cases also present spine deformities, known as kyphoscoliotic deformities.3
How is Carasil diagnosed?
Observable signs and symptoms
The signs and symptoms of Carasil are first assessed through an on-site examination to check for classic symptoms of the disease listed above. To confirm diagnosis, a neurological examination is then conducted to test for cognitive ability, memory and motor coordination.2 This includes using a tendon reflex test, hand-eye coordination tests and classic recall questions from the doctor.3
Lab-based testing
Genetic testing, such as next-generation sequencing (NGS), is then used to check for mutations in the HTRA1 chromosome gene, and once identified, testing within family members is also conducted so that further development can be monitored of this condition.5
Neuroimaging techniques
Neuroimaging is also used, where a magnetic resonance imaging (MRI) or computed tomography (CT) of the brain is taken to see any abnormalities within its structure.4 If Carasil is present, the white matter of the brain will visibly increase, and the presence of black spots showing microhemorrhages and hyperintensities of the structures will form, called leukoaraiosis.5 Leukoaraiosis is the presence of an abnormality in white matter, which can be seen in this photo below, comparing it to an MRI of a healthy brain.6
What are the treatments for carasil?
As this is a genetic disease, there are currently no specific treatments for this condition, but there are ways to manage the condition to decrease the level of discomfort and increase life expectancy.4 Many treatments focus on the reduction of strokes, which use antiplatelet agents and anticoagulants to decrease the likelihood of a blood clot forming. Genetic counselling is also used as part of primary care for the patient, and close monitoring of symptoms allows targeted treatment and further research opportunities.6
Summary
Carasil impacts the function of the brain due to genetic mutations that influence blood and oxygen supply reaching it. Currently, there are no ways to diagnose Carasil early; however, physiological signs and symptoms that appear around the ages of 20 to 30 years old allow us to accurately diagnose and monitor disease progression. The main techniques used are:
- Genetic testing to sequence the mutated gene in the lab
- Neuroimaging, such as MRI, CT, to check structural abnormalities in the brain
- Tendon jerk reflex and hand-eye coordination tasks to test for muscles and joints
- General signs and symptoms that appear when the patient is presented
References
- CARASIL - Symptoms, Causes, Treatment | NORD [Internet]. [cited 2025 Jul 9]. Available from: https://rarediseases.org/rare-diseases/carasil/.
- Badachi S, John SK, Sekhar M, Mathew T. CARASIL; The Backache, Baldness, Brain Attack Syndrome: The Indian Scenario. Ann Indian Acad Neurol [Internet]. 2020 [cited 2025 Jul 9]; 23(4):559–61. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7657304/.
- Devaraddi N, Jayalakshmi G, Mutalik N. CARASIL, a rare genetic cause of stroke in the young. Neurol India [Internet]. 2018 [cited 2025 Jul 9]; 66(1):232. Available from: https://journals.lww.com/10.4103/0028-3886.222859.
- Alex - The Leukodystrophy Charity [Internet]. CARASIL - Cerebral Autosomal Recessive Arteriopathy with Subcortical infarcts and Leukoencephalopathy; [cited 2025 Jul 9]. Available from: https://alextlc.org/condition/cerebral-autosomal-recessive-arteriopathy-with-subcortical-infarcts-and-leukoencephalopathy-carasil/.
- [Internet]. CARASIL | STROKE MANUAL; [cited 2025 Jul 9]. Available from: https://www.stroke-manual.com/carasil/.
- Pfleger R, Sharma R, Gaillard F. Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL). In: Radiopaedia.org [Internet]. Radiopaedia.org; 2014 [cited 2025 Jul 9]. Available from: https://radiopaedia.org/articles/29111.
