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 most famous degenerative movement disorder, a genetic anomaly with an autosomal-recessive transmission 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 is diagnosed as Friedreich's ataxia. Medical statistics report about 100, 000 sick people from this ataxia, of which 1, 200 are Italian.
Most often, Friedreich's ataxia begins in infancy, particularly in children aged between 6 and 15; in some cases, the ataxic syndrome occurs after the age of 20 (late onset).
Genetic transmission
Being a pathology with autosomal-recessive transmission, the parents, clinically in good health, can transmit the Friedreich ataxia gene to the offspring when both the mother and the father are healthy carriers, with a probability of 25% (1 patient every 4 children).
Currently, Friedreich's ataxia is diagnosed by a molecular genetic test, which is possible by analyzing a blood sample.
Around 1996, research in the molecular field took a very important turn, as the gene responsible for Friedreich's ataxia was isolated: it is the FXN gene - also known as X25, located at the level of chromosome 9 (region 9q13-q21) - which codes for frataxin (or frataxin), a protein consisting of repetitions of the GAA triplet (Guanine-Adenine-Adenine) in the first non-coding site of the gene (intron). As already mentioned in previous articles, frataxin is localized at the mitochondrial level, 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
Based on the onset age of Friedreich's ataxia and the severity of the disorder, different symptom patterns 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 not able to maintain a certain correct posture for long periods, especially when he is in crowded places. Friedreich's ataxia is destined to degenerate: over time, the patient presents obvious disorders in carrying out the simplest activities, such as eating, speaking, writing, etc. Friedreich's ataxia is a debilitating disease, so much so that often the affected patient is forced to move around in a wheelchair; in cases of greater severity, the syndrome could also cause serious 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 have an evident swelling of the walls of the interventricular septum, an altered electrocardiogram and an increase in 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 obvious 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 to identify the mutated gene; however, even MRI is 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 semi-annual blood glucose check is recommended.
Given the possible cardiac problems deriving from Friedreich's ataxia, the doctor can prescribe specific pharmacological specialties to the patient, in order to keep any symptomatological degenerations under control.
