Autosomal Dominant hereditary Cerebellar Ataxia

ADCA is a hereditary and slowly worsening brain disease of the cerebellum. It is a rare hereditary form of ataxia. Progressive neurodegenerative means that the condition of the nerve tissue deteriorates more and more. It is caused by damage to the little brain (cerebellum) that is involved in movement and maintaining balance). The nerve pathways in the legs may also be affected.

 

Explanation

Ataxia is a disorder of movement. The balance and coordination of movement are affected. A person with ataxia moves arms, legs and torso jerkily and uncontrollably. As a result, he or she appears clumsy. Speech can also be affected. The patient may have difficulty pronouncing words clearly. The patient may tremble. These symptoms resemble the symptoms of drunkenness.

 

Characteristics of ADCA

- gradual increase in uncertainty when standing and walking (gait ataxia)

- speech disorders (dysarthria)

-eye movement disorders (rapid or slow eye movements; saccades or nystagmus)

- difficulty seeing / visual disorders (retinopathy or double vision)

swallowing disorders (dysphagia);

- fatigue. Polyneuropathy is also common in ADCA patients. In polyneuropathy, the nerve endings in the arms and legs are affected. Fatigue is often the most frequently mentioned complaint.

 

Cerebellum

Such damage to the cerebellum can also be a consequence of, for example, traumatic brain injury or a stroke. In ADCA, the damage is caused by a hereditary disease. Certain cells in the cerebellum do not function because they die or shrink (atrophy).

ADCA is a hereditary disease. It therefore occurs in certain families. The family data are therefore an important source of information to help diagnose the disease.

In the Netherlands, there are an estimated 218 families in which the disease occurs. The course is progressive and to date there are no medicines or treatments that can stop or cure the disease.

 

 

SCA

The genetic, hereditary known types of the disease ADCA are referred to as SCA, spinocerebellar ataxia type 1.
Spino refers to the spinal cord and cerebellar to the
cerebellum. Ataxia means an uncoordinated way of walking.
SCA1 is a rare, autosomal dominant, hereditary disease: that is, a child of a parent with this disease has a fifty percent chance of inheriting and developing the disease, both boys and girls.
Autosomal means that the defective gene is on a non-sex chromosome. Only one faulty gene is needed to pass on the disease.

 

The condition is progressive. This means that the disease worsens over time. Characteristic are the gait disturbances, difficulty speaking and slurred speech (dysarthria), problems with balance and equilibrium, eye movements that shoot past the target when you want to look at something (hypermetric saccades), eyeball twitches / wobbly eye (nystagmus) and mild swallowing disorders. Later, the eye movements for finding a fixation point (saccades) become slower.

 

Spinocerebellar ataxia type 2 (SCA2) is a subtype of type 1. Characteristic of this type is difficulty sitting or standing upright (truncal ataxia), difficulty with speech due to a problem with the use of the muscles of the lips, tongue, palate and vocal cords (dysarthria) and slower eye movements to find a fixation point (saccades). Weakened or paralyzed eye muscles (ophthalmoparesis) are less common, as is a movement disorder with involuntary, non-rhythmic movements of the face or limbs (chorea).

 

Ataxin-1 protein error

SCA1 is caused by an incorrect protein (ataxin-1) being produced in the brain. This causes damage to the cerebellum and the brain stem, which disrupts many processes.

 

The various SCAs have many clinical similarities. Within one type of SCA, the clinical symptoms can vary greatly. SCAs occur all over the world. However, there are notable differences in the occurrence per country described for a number of SCA types. In addition to these differences, SCA appears to occur less frequently in people of the Negroid race. SCA1 is caused by a defect in the so-called ATXN1 gene.

 

Geographical distribution

Regionally, some differences have been described in the Netherlands: SCA3 was mainly found in the provinces of Groningen and Drenthe and SCA2 mainly in families originally from Friesland.

Patients with SCA1 and SCA6 often come from the middle and west of the country.
Information about: SCA14, SCA17, SCA28, SCA3, SCA6, SCA7, SCA8 and via this website.

 

Symptoms

The first symptoms of the disease usually occur between the ages of 30 and 50. The symptoms can vary per individual and in severity. It usually starts with an uncertain gait and increasing uncertainty when moving the limbs. There are often also speech disorders, difficulty talking. Trembling, chewing and swallowing problems, eye movement disorders and problems with vision also occur. Usually no behavioral or character changes occur. It can lead to loss of mobility and early death.

 

Treatment

Speech therapy, physiotherapy or occupational therapy may help to limit the disabling effects and to maintain the quality of life as much as possible. Painkillers relieve any pain and certain medications combat the uncontrolled shaking. There is no medicine for ADCA yet. With prism glasses, the symptoms of double vision can often be improved.
Scientific research is being conducted into both a possible treatment for SCA1 and the development of the right experiments to test this.

 

More information:

PDF of the Dutch doctors association
ADCA Association the Netherlands

https://ataxie.nl/

https://ataxie-adca-sca.blogspot.com/2019/06/wetenschappelijk-onderzoek-naar-ataxie.html

https://rarediseases.info.nih.gov/diseases/4346/autosomal-dominant-cerebellar-ataxia

https://patient.info/doctor/cerebellar-disorders

Patient
Rightdiagnosis

• SCA1
• SCA14
• SCA17 
• SCA28
• SCA3
• SCA6
• SCA7
• SCA8