FRIEDREICH'S ATAXIA

Friedreich's ataxia: definition

Friedreich's ataxia owes its name to Nikolaus Friedreich, who in 1863 described the symptoms of this kinetic disorder; among the dyskinesias, Friedreich's ataxia certainly represents the best known degenerative movement disorder, an autosomal genetic anomaly - necessary responsible for the progressive and inevitable damage to the central and peripheral nervous system.

Incidence

As already mentioned, Friedreich's is certainly the most common form of hereditary ataxia: just think that half of the ataxic syndromes are diagnosed as Friedreich's ataxia. Medical statistics show approximately 100,000 subjects suffering from this ataxia, of which 1,200 are Italian.
Most often, Friedreich's ataxia begins in infancy, particularly in children between the ages of 6 and 15; in some cases, the aforementioned ataxic syndrome occurs after the age of 20 (late onset).

Genetic transmission

Being an autosomal-recessive disease, the parents, clinically in good health, can transmit the Friedreich ataxia gene to their offspring when both the mother and the father are healthy carriers, with a 25% probability (1 patient every 4 children).
Currently, Friedreich's ataxia is diagnosable by a molecular genetic test, possible by analyzing a blood sample.
Around 1996, research in the molecular field has brought a very important turning point, since the gene responsible for Friedreich's ataxia has been isolated: it is the FXN gene - also known as X25, located at the level of chromosome 9 (region 9q13-q21) - which encodes frataxin (or frataxin), a protein consisting of repetitions of the triplet GAA (Guanine-Adenine-Adenine) in the first non-coding site of the gene (intron). As already mentioned in previous articles, frataxin is localized at the level mitochondrial, and is responsible for the regulation of iron and the disposal of metabolic waste produced by the energy mechanisms in the mitochondria.Under standard conditions, the sequences of the aforementioned nucleotide bases do not count more than 40 triplets (healthy subjects), but in ataxic patients the GAA sequences are over 100 or even 1,200 [taken from www.atassiadifriedreich.it]

Symptoms

On the basis of the "age of onset" of Friedreich's ataxia and the severity of the disorder, different symptom pictures can be constructed; it follows that the symptoms derived from Friedreich's ataxic syndrome are not always constant. However, usually the very first symptoms affect balance and motor control, consequently the affected subject is unable to maintain a certain correct posture for long periods, especially when in crowded places. Friedreich's ataxia is destined to degenerate: over time, the patient presents evident disturbances in carrying out the simplest activities, such as eating, speaking, writing, etc. Friedreich's ataxia is a disabling disease, so much so that often the affected patient is forced to travel in a wheelchair; in cases of greater severity, the syndrome could also cause severe heart disease, sometimes fatal.
Other symptoms related to Friedreich's ataxia are scoliosis and hollow foot (in which the sole of the foot is evidently arched); moreover, almost all affected patients present an evident enlargement of the interventricular septal walls, an altered electrocardiogram and a increased heart rate. Therefore, Friedreich's ataxia does not only involve the nervous system: many affected patients are diagnosed with progressive heart disease, responsible for the abnormal enlargement of the heart muscle and an evident difficulty in pumping blood.

Diagnosis and therapies

Molecular diagnosis, which can be performed by taking the patient's blood, is certainly the most appropriate method for identifying the mutated gene; however, magnetic resonance imaging is also useful, as are neurophysiological examinations, used to evaluate the transmission of nerve stimuli.
Currently, laboratory tests are also available to verify the hypothetical diagnosis of a healthy carrier. Medical statistics report that 20% of patients with Friedreich's ataxia are diabetic: in this regard, an annual or six-monthly blood glucose check is recommended.
Considering the possible heart problems deriving from Friedreich's ataxia, the doctor can prescribe specific pharmacological specialties to the patient, in order to control any symptomatic degeneration.