mind helvetica, physician sans-serif; font-size: 1em; background-color: #92d2dd; border: medium solid #333333; text-align: center;">One can be affected by ataxia telangiectasia with parents who are not.

cialis helvetica,sans-serif; font-size: 1em; background-color: #92d2dd; border: medium solid #333333; text-align: center;">Each parent is carying an anomaly (in most cases).

AT is autosomal and recessive

Autosomal

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that equally affects the two sexes.

Récessif

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In our genetic heritage, we all have two alleles of the same gene, ie twice the copy of the gene. One comes from our mother and one from our father.

A gene is called "dominant" when one altered allele is sufficient to express the abnormality. In this case, the parent who transmit it is ill too.

A gene is called "recessive" if both abnormal copies of it are necessary to express a disease. In this case, neither parent has an anomaly whereas they are both carriers of a defective copy of the gene. This is the case of ATM: it requires that each parent carries an altered allele and transmit it to their child.

So there is 1 in 4 chance that the couple had a child with ataxia telangiectasia. In rarer cases, an allele may be altered during design, giving the same result.

Genetic counseling and the opportunity to make a prenatal diagnosis is possible, but only if a child is already concerned within the family and whether the mutation causes the disease is identified.