In their first year of life children with juvenile NCL develop completely normally. The first signs generally appear in the form of gradual loss of sight
beginning around the age of six. In one to three years this will lead to complete blindness.
Around the age of eight the first signs of mental deterioration appear. The children forget what they learned before, such as maths and writing. Because they are fully aware of this development, it often leads to dramatic personality changes. At the age of 11, speech becomes difficult; 2 years later, they often completely lose the ability to hold a conversation. Alongside this, first signs of movement loss appear and the little patients will soon become dependent on a wheel chair. Further symptoms are epilepsy and cardiological problems. By the time the child is twenty, the disease will have reached a stage where nearly all capabilities have disappeared.
The NCL patient will lose control of all their bodily functions and need to be nourished artificially and taken care of 24 hours a day. They usually die of dehydration or respiratory paralysis before their 30th birthday. In Germany around 700 children are affected by jNCL. Worldwide there are around 70,000 sufferers.
The juvenile form of NCL is caused by a defect in genetic material, which is a recessive gene. The affected gene lies on chromosome 16. This genetic mutation leads to fat-like material collecting in the nerve cells because the natural metabolising protein is defective. The cells cannot clean themselves of pollutants caused by energy production, become dirty, and later die. The eyes are the first organ to be affected - leading to blindness - shortly followed by the brain.
NCL involves the mutation of one of 13 different NCL genes. They have the following symptoms in common: loss of sight, dementia, loss of motor functions and epilepsy. These differentiate themselves primarily by the age at which symptoms appear and in the speed with which the disease progresses. Most forms first show symptoms during childhood, but adults can also be affected. All forms of child and youth NCL are autosomal recessively inherited.
The most common NCL-forms in Germany are the infantile NCL (CLN1, starts at 6 to 24 months), the late-infantile (CLN2, starts at 2 to 4 years) and the juvenile NCL (CLN3, starts at 5 to 20 years).
The one characteristic that all forms share is that they are currently incurable. Due to the fact that, depending on the type, different genes are affected, no single drug can be developed to tackle all the forms of NCL. The NCL foundation focusses on juvenile NCL.
In 2017 the first treatment, the enzyme replacement therapy, for CLN2 was officially approved.
Until NCL is correctly diagnosed, about two to four years and various consultations are required. To shorten this time and avoid a high number of misdiagnoses, it is necessary to educate ophthalmologists and paediatricians. Currently there are 13 known types of NCL. A gene test gives certainty if there is a mutation of the NCL gene, which causes the disease.
For further information please contact Dr. Herman van der Putten.