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CLN2 (neuronal ceroid lipofuscinosis type 2) is also referred to as childhood dementia. In a relatively short time after birth, the child not only begins to regress in development and loses skills such as walking, speaking, and blindness, as well as seizures. The disease is fatal, although theoretically there are methods of treating it, but in Poland the availability of them is very limited.

CLN2( childhood dementia , Englishneuronal ceroid lipofuscinosis 2 ) is a rare disease , belongs to a group of diseases that are referred to as neuronal ceroid lipofuscinosis.

All these units have some common characteristics - they are caused by genetic mutations, and their symptoms appear typically in the early childhood period, but the differences concern specific genes, which are mutated in patients.

Neural ceroid lipofuscinosis is a rare disease - it is estimated that one of these units occurs in 1 in 100,000 people from the general population. In the case of the CLN2 discussed here, so far in the medical literature slightly more than 300 cases of this entity have been described around the world.

CLN2 (childhood dementia): causes

As mentioned above, CLN2 is a genetic disease - mutations in the TPP1 gene lead to childhood dementia. It is responsible for coding the genetic material for one specific enzyme, which is tripeptidyl peptidase 1.

This substance is normally present in lysosomes and is responsible for the breakdown of various peptides into amino acids.

In the case of the mutation of the TPP1 gene, which is the basis of neuronal ceroid lipofuscinosis type 2, there is a complete absence or a significantly reduced synthesis of the above-mentioned enzyme.

In this situation, there is an accumulation of proteins and various other substances within the lysosomes. These organelles are present in various cells of the human body, and in fact, abnormal deposits appear in many of them, but the nerve cells are the most sensitive to their accumulation - so in the course of CLN2 there is progressive damage and death of neurons.

Childhood dementia is a disease that is inherited inan autosomal recessive manner, which means that the disease requires the presence of two copies of the mutated gene in the patient.

CLN2 (childhood dementia): symptoms

Children with CLN2 develop normally until a certain point in their lives, and eventually - usually between the ages of 2 and 4 - young patients develop various symptoms of childhood dementia. Usually, the first symptoms of the disease are:

  • imbalance
  • recurring seizures
  • involuntary movements in the form of myoclonus
  • visual disturbance

Over time, the aforementioned ailments may increase in severity, and more and more problems appear in patients.

The disease affects the skills acquired by the child in the earlier stages of life - it may even happen that a small patient who has previously sat, walked or even talked, gradually loses these abilities.

There may be deepening intellectual disability, children with childhood dementia may also experience various types of behavioral disorders.

CLN2 (childhood dementia): diagnosis

The basic methods for the diagnosis of CLN2 are genetic tests (in which it is possible to detect mutations responsible for the disease) and enzymatic tests (in which it is possible to find a reduced activity of enzymes that break down proteins).

However, various other studies show some abnormalities related to childhood dementia - they can be found in:

  • blood count (where you can see atypical vacuolated lymphocytes)
  • skin biopsy or biopsy of some other tissue (where deposits of undegraded protein compounds can be detected)
  • imaging tests (such as, for example, computed tomography or magnetic resonance imaging of the head, in which it is possible to find out that the patient has foci of nerve tissue atrophy)

CLN2 (childhood dementia): treatment

In children with neuronal ceroid lipofuscinosis type 2, symptomatic treatment is used primarily - the incidence of seizures can be reduced by the use of anticonvulsants, while regular rehabilitation can positively affect the motor skills of patients.

However, due to the seriousness of childhood dementia, attempts are still being made to find causal methods of its treatment. Research is being conducted on the possibility of using in patients, among others:

  • gene therapy
  • stem cells
  • immunosuppression

The most hope, however, isenzyme replacement therapy .

The American FDA in April 2022 approved the use of cerliponase alfa, an enzyme preparation obtained by recombinant DNA techniques. This measure is designed to replace the missing enzyme in childhood dementia and slow the progression of the disease.

The preparation is administered directly to the cerebrospinal fluid (it is introduced into the ventricular system of the brain through a specially introduced port).

The effects of CLN2 treatment with cerliponase alpha seem promising, but there is one problem here: the availability of therapy.

As the preparation is available to patients living in the United States or Germany, treatment with its use is not reimbursed in Poland.

In this case, however, it is important to start the therapy as soon as possible, before the disease leads to changes (e.g. atrophy of nerve cells), the reversal of which will no longer be possible.

CLN2 (childhood dementia): prognosis

The prognosis of patients with childhood dementia is unfortunately not good.

Since the first symptoms of the disease appear in a child, they gradually increase in intensity, and finally, even in the first decade of life, the patient may lose the ability to move or even exist independently.

Most CLN2 sufferers do not live to be in their teens.

It is different only when the first symptoms of the disease appear a little later than usual, i.e. after the age of 4 - in such a situation the symptoms of the disease are usually slightly less intense and the survival of patients is also longer than in typical forms of the disease, it so happens that patients with childhood dementia with a later onset live into adulthood.

About the authorBow. Tomasz NęckiA graduate of medicine at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

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Genetic diseases