PPT1-related neuronal ceroid lipofuscinosis
What is PPT1-related Neuronal Ceroid Lipofuscinosis?
PPT1-related neuronal ceroid lipofuscinosis (NCL) is an inherited disease that causes degeneration of the brain leading to a progressive loss of intellectual abilities and motor skills. The condition also causes blindness and seizures and typically leads to an early death. There are several forms of NCL, largely differentiated by the gene responsible and the age at which symptoms begin. Mutations in the PPT1 gene typically result in either the infantile or juvenile form of NCL.
The infantile form of NCL (INCL) usually begins to cause noticeable symptoms between 6 months and 24 months of age. Initially, infants may show developmental delays, jerking movements, and/or seizures. In addition, these infants will typically have small heads. Blindness and seizures generally develop by 24 months of age, after which cognitive functions will deteriorate. The child’s movement typically becomes spastic and uncontrolled, and he or she will experience a loss of motor skills and intellectual abilities.
The symptoms of juvenile NCL (JNCL), also called Batten disease, often begin between the ages of 4 and 10. Children with JNCL rapidly lose their vision, which is often the first noticeable symptom. They typically become completely blind within two years. Most children with JNCL develop periodic seizures between the ages of 5 and 18, with cognitive functions declining between the ages of 8 and 14. They often experience speech and behavioral problems in childhood; psychiatric problems such as disturbed thoughts, attention difficulties, and aggression; and dementia or memory problems. Individuals with JNCL also show a decline in motor function and may have difficulty controlling body movements.
How Common is PPT1-related Neuronal Ceroid Lipofuscinosis?
The worldwide prevalence of NCL (all forms) is approximately 1.3-7/100,000. These diseases are most common in Scandinavian countries but occur elsewhere as well. There are multiple genes associated with NCL, and a subset of all NCL is caused by mutations in the PPT1 gene. Mutations in the PPT1 gene are most frequent among the Finnish population, where the prevalence is estimated to be 1 in 20,000. JNCL is most common in Iceland, where the prevalence is estimated to be 7 in 100,000. The exact proportion of NCL cases that are caused by mutations in the PPT1 gene is unknown.
How is PPT1-related Neuronal Ceroid Lipofuscinosis?
There is no treatment for the underlying cause of PPT1-related NCL. Available treatments address the symptoms of PPT1-related NCL as they arise. Various medications may be useful for improving seizures, movement problems, sleep difficulties, mood disorders, excessive drooling, and digestive problems. In some individuals, a feeding tube is also helpful.
What is the Prognosis for an Individual with PPT1-related Neuronal Ceroid Lipofuscinosis?
The prognosis for an individual with PPT1-related NCL is dependent upon the disease subtype. Individuals with INCL or JNCL will become blind and experience deterioration of both motor skills and intellectual abilities. They will eventually enter a vegetative state and become totally dependent on others to care for them.
Lifespan is also shortened for individuals with PPT1-related NCL. For those with INCL, death usually occurs in childhood. For those with JNCL, death usually occurs in the late teens, 20s, or 30s.