Canavan Disease: Causes, Symptoms and Diagnosis

Canavan disease is a rare, inherited disorder that primarily affects infants and young children. Characterised by developmental problems and loss of motor skills, the disease attacks the nerve cells in the brain.

Because the condition can result in severe complications and even be life-threatening, understanding its causes, early symptoms, and available management options is crucial for timely diagnosis and better care outcomes.

This article provides a detailed overview of Canavan disease, its causes, symptoms, diagnosis, and approaches to treatment and care.

What is Canavan disease?

Canavan disease is a type of leukodystrophy, a group of genetic conditions that affect the brain, spinal cord, and nerve fibres. The disease generally develops during infancy and progresses rapidly as the nervous system becomes increasingly damaged, which can even result in death.

Canavan disease causes the destruction of myelin, the fatty coating that protects nerve fibres and enables proper nerve signal transmission throughout the nervous system. As the protective myelin layer gets destroyed, affected children experience neurological decline, including loss of motor skills, muscle weakness, and severe developmental delays.

What are the Different Types of Canavan Disease?

Depending on when the disease occurs, Canavan disease can be of two types:

1. Infantile Canavan disease: This is the most common and severe form of the condition. Affected infants typically appear healthy at birth, but symptoms begin to emerge between 3 and 5 months of age. Life expectancy is severely limited, with most children not surviving beyond childhood or early adolescence.
2. Juvenile Canavan disease: This is a milder, less common form that develops later in childhood. While life expectancy is longer, the condition still causes significant developmental challenges.

What are the Causes of Canavan Disease?

Canavan disease’s causes are genetic. It develops due to changes in the ASPA gene, which is responsible for the production of an Aspartoacylase. It’s an enzyme that breaks down N-acetyl-L-aspartic acid (NAA), found in the brain. ASPA gene mutations prevent this breakdown, causing high levels of NAA buildup in the brain.

This buildup affects the formation of the myelin sheath and even destroys the existing ones, leaving the nerves without a protective covering. With time, the brain tissue breaks down and becomes filled with tiny fluid pockets, resembling a sponge. This damage prevents the brain from properly sending and receiving signals.

What are Some Canavan Disease Symptoms?

Children with Juvenile Canavan only face mild coordination problems and developmental issues like delays in speech and movement. However, Infantile Canavan disease’s symptoms are quite severe:

• Weak and stiff muscles or floppiness.
• Developmental delays, with difficulty in sitting, walking, standing, and talking.
• Abnormally large head.
• Poor coordination of mental and muscular activity.
• Problems in eating and swallowing.
• Trouble in focusing or tracking objects.
• Unresponsive behaviour with lethargy and irritability.
• Vision or hearing problems.
• Muscle spasms that begin in the first year of life.

How is Canavan Disease Diagnosed?

If an infant shows Canavan disease’s symptoms, doctors usually perform urine tests, a brain scan, and blood and cerebrospinal fluid (CSF) tests to detect elevated NAA levels in urine, brain tissue, blood, and CSF, respectively. In addition, molecular genetic testing can also confirm the ASPA gene mutation in the child’s DNA. If the child has two disease-causing variants of the gene (one from each parent), the diagnosis is confirmed.

If both the parents test positive for the gene mutations, they can also have prenatal testing for their unborn baby. This involves testing the amniotic fluid (Amniocentesis) and placental cells (Chorionic Villus Sampling) for genetic mutations during the pregnancy.

How to Manage Canavan Disease?

Because there is no cure available for the Canavan disease, managing it is the best way forward. Here are some management approaches that parents can follow for their child:

• Physical therapy to improve muscle tone and posture.
• Medications to control seizures if they occur.
• Nutritional support, including the use of feeding tubes when necessary.
• Respiratory support when breathing difficulties arise.
• Genetic counselling for families.

While the interventions mentioned above cannot reverse the disease, they can help maximise comfort, prevent complications, and provide crucial support for both the child and their family.

If a child is experiencing symptoms of Canavan disease, parents should consult a healthcare provider immediately and download the Dr Lal PathLabs app for convenient booking of necessary genetic and diagnostic tests.

FAQs

1. What is Canavan’s disease caused by?
   Canavan’s disease is caused by mutations in the ASPA gene, which results in deficiency of the enzyme aspartoacylase. Without this enzyme, a substance called NAA builds up in the brain, damaging the protective myelin coating around nerve cells and causing neurological deterioration.
2. Is Canavan’s disease curable?
   No, there is no cure for Canavan disease. Currently, medical care is centred on symptom management and supportive therapies to maximise the child’s comfort and quality of life.