Canavan disease is a progressive hereditary disorder of the central nervous system (brain and spinal cord). It has been recognized since the middle of the 20th century.
Symptoms usually appear early in life. The more severe form of the disease occurs in infants in the first 6 months of life and progresses rapidly. Affected babies are floppy and unable to hold their heads. The head may appear abnormally large. Such infants never achieve normal milestones such as sitting and standing although they often respond socially by smiling, laughing, and reaching for objects. Later they demonstrate irritability and muscles become stiffer. Eating is often a significant problem and feeding tubes may be required to maintain nutrition. Longevity is limited and few live beyond several years.
A milder form of the disease occurs among children who show symptoms later in the first decade of life. Speech and motor development are delayed but they can often attend regular school with some tutoring and speech therapy. These children may live to adolescence or even to early adulthood.
Vision is reduced in all children although no data are available to document how much they actually see. The optic nerve (which is part of the brain) shows damage known as optic atrophy. Children are able to track objects shown to them, however, so complete blindness is not always present. Seizures often occur and some patients have hearing problems.
This is an autosomal recessive disorder requiring two copies of a mutated gene. Parents who must each carry one copy show no signs of Canavan disease but each of their children have a 25% risk of inheriting both copies and therefore having this condition.
Children with Canavan disease have a poor prognosis. The early the onset of symptoms, the more severe the symptoms and the more rapidly progressive is the disease. A neurologist is usually the specialist who makes the clinical diagnosis and he will often rely on X-ray imaging of the brain to document the damage. The diagnosis may also be suggested by chemical studies of the urine but gene studies are necessary to document the suspected diagnosis.
There is no cure for this condition. However, certain treatments can be beneficial. These include speech therapy, physical therapy, anti-seizure drugs, nutritional supplements, and feeding tubes. Hearing devices and low vision aids should be considered in appropriate individuals.