Ataxia-Telangiectasia is a very rare hereditary pediatric disease that affects one child in each 30.000-100.000 newborns. It is an autosomal recessive pathology: parents are free of symptoms but are carriers and have one possibility in four of having an affected child.
The disease begins showing symptoms during childhood, at about two or three years of age, with the difficulty of limb movement coordination (cerebellar ataxia). It progressively aggravates. The disease becomes Telangiectasia: small dilated capillaries most of which are situated in the eyes sclera and on the cutis. When language is acquired, children find it difficult to articulate words. Pathology goes with immunologic problems which lead affected children to develop frequent and hard to get over broncho-pulmonary infections. Moreover, a third of patients generate tumors, often lymphomas and leukemia, which represent the main death risk (second only to breathing problems).
At the central nervous system level there is present grievous cerebellum degeneration, the part of the brain which enables movement coordination.
1. Progressive trunk and gait Ataxia which appears within one to three years old;
2. Progressive languages alterations;
3. Oculo-cutis Telangiectasia's, usually around six years old;
4. Frequent infections along with humoral and cellular immunodeficiency;
5. Neoplasia predisposition, usually leukemia or lymphoma.
Others characteristics include premature aging and endocrine anomalies.
The main and most disabling Ataxia-Telangiectasia characteristic is progressive and cerebellar Ataxia. Disease frequently begins with walking acquisition that is clumsy and unsteady. Within four-five years old, arms movements become uncoordinated (Ataxia) and language becomes clumsy (Dysarthria). Eye movements become jerkily, moreover patient turns head instead of eyes when looking sideways (ocular Apraxia). Ability to write becomes involved within seven-eight years old. Tremors are present. Within nine-ten years old a light intellective decline occurs. At about ten years of age patients are generally obliged to use a wheelchair. Medium average life expectation is less then twenty-five years old. These children need help to dressing, eating, washing and using the toilet.
Neurological problems continue to advance over the course of time: muscle power decreases, especially in the legs, hands, feet and fingers (contractures appear). Ataxia-Telangiectasia children usually have normal intellective skills even when slow answers cause difficulty in IQ evaluation tests.
In the course of time the disease becomes manifest: Ataxia advances in an important way, ocular movements tend to fallow an object with less sight and language becomes more and more difficult.
At the cellular level a hypersensitivity to ionizing radiations manifests (X or gamma rays). Laboratory tests can verify this hypersensitivity and have been diagnostician of this disease for years. Ataxia-Telangiectasia children cannot be exposed to conventional dose of ionizing radiations and in case of neoplasia they must be subjected to specific softer therapy.
Disease is progressive and leads to death generally in the second decade because of bronchopolmonar inter-current infections or neoplasias.
Absence or diminution of various immunoglobulins (gA, IgE and isotypes, IgG2, IgG4) has been checked basically in every child. These alterations have been caused by a reduced synthesis and have been associated to thymus hypoplasia, follicle lymph node loss, lack of hypersensitivity delayed reaction, lymphopenia and slow circling antibody formation.
This immunodeficiency state explains evident susceptibility of these patients to recurrent pulmonary infections and to bronchiectasis.
Magnetic resonance shows volume reduced cerebellum.
Most subjects do not present appreciable protein ATM (altered) levels in the cellules, even if some children have small quantities of this protein and have lighter symptoms.