What is Batten Disease/NCL?
Batten disease is a rare, fatal autosomal recessive inherited disease of the nervous system (a neurodegenerative disorder) that begins in childhood. It is named after the British pediatrician, Frederick Batten who first described the juvunile form of neuronal ceroid lipofuscinosis (NCL) in 1903. The name, Batten, is now commonly used to encompass three forms of NCL: infantile, late infantile and juvenile onset. All forms have the same basic cause; a gene is mutated causing a deficiency in an enzyme responsible for ridding waste from the central nervous system cells. Without this enzyme, small organelles within the cell called lysosomes, become clogged with toxic material within the neurons of the brain. As a result, children with Batten Disease start to suffer seizures, progressively lose their motor skills, their sight and mental capacity, eventually becoming blind, bedridden and unable to communicate. Today, Batten disease is always fatal.
Forms
There are four main types of NCL (types 1-4), including two forms that begin earlier in childhood and a very rare form that strikes adults. The symptoms are similar but they become apparent at different ages and progress at different rates.
Infantile NCL (Santavuori-Haltia disease): begins between about 6 months and 2 years of age and progresses rapidly. Affected children fail to thrive and have abnormally small heads (microcephaly). Also typical are short, sharp muscle contractions called myoclonic jerks. Initial signs of this disorder include delayed psychomotor development with progressive deterioration, other motor disorders, or seizures. The infantile form has the most rapid progression and children live into their mid childhood years.
Late Infantile NCL (Jansky-Bielschowsky disease) begins between ages 2 and 4. The typical early signs are loss of muscle coordination (ataxia) and seizures along with progressive mental deterioration. This form progresses rapidly and ends in death between ages 8 and 12.
Juvenile NCL (Batten Disease) begins between the ages of 5 and 8 years of age. The typical early signs are progressive vision loss, seizures, ataxia or clumsiness. This form progresses less rapidly and ends in death in the late teens or early 20s, although some may live into their 30s.
Adult NCL (Kufs Disease or Parry’s Disease) generally begins before the age of 40, causes milder symptoms that progress slowly, and does not cause blindness. Although age of death is variable among affected individuals, this form does shorten life expectancy.
Inheritance
Childhood NCLs are autosomal recessive disorders; that is, they occur only when a child inherits two copies of the defective gene, one from each parent. When both parents carry one defective gene, each of their children faces one in four chance of developing NCL. At the same time, each child also faces a one in two chance of inheriting just one copy of the defective gene. Individuals who have only one defective gene are known as carriers, meaning they do not develop the disease, but they can pass the gene on to their own children.
Adult NCL may be inherited as an autosomal recessive (Kufs) or, less often, as an autosomal dominant (Parry’s) disorder. In autosomal dominant inheritance, all people who inherit a single copy of the disease gene develop the disease. As a result, there are no unaffected carriers of the gene.
How Many People Have Batten Disease/NCL?
Batten Disease/NCL is very rare, occurring in an estimated 2 to 4 of every 100,000 live births in the United States. Though it is more common in Finland, Sweden, other parts of northern Europe and Newfoundland, Canada, less than five hundred children in the world have this disease at any given time.
Diagnosis
Because vision loss is often an early sign, Batten disease/NCL may be first suspected during an eye exam. An eye doctor can detect a loss of cells within the eye that occurs in the three childhood forms of Batten disease/NCL. However, because such cell loss occurs in other eye diseases, the disorder cannot be diagnosed by this sign alone. Often an eye specialist or other physician who suspects Batten disease/NCL may refer the child to a neurologist, a doctor who specializes in disease of the brain and nervous system. In order to diagnose Batten disease/NCL, the neurologist needs the patient’s medical history and information from various laboratory tests.
Diagnostic tests used for Batten disease/NCLs include: blood or urine tests, skin or tissue sampling, an electroencephalogram (EEG), electrical studies of the eyes and brain scans. A recent development in diagnosis of Batten disease/NCL is the use of enzyme assays that look for specific missing lysosomal enzymes for infantile and late infantile only. This is a quick and easy diagnostic test.