Ataxia telangiectasia
| Ataxia-telangiectasia | |
|---|---|
| Classification and external resources | |
| Specialty | neurology |
| ICD-10 | G11.3 |
| ICD-9-CM | 334.8 |
| OMIM | 208900 |
| DiseasesDB | 1025 |
| MedlinePlus | 001394 |
| eMedicine | derm/691 oph/319 |
| MeSH | D001260 |
| GeneReviews | |
| Orphanet | 100 |
Ataxia-telangiectasia (AT or A-T), also referred to as ataxia-telangiectasia syndrome or Louis–Bar syndrome, is a rare, neurodegenerative, autosomal recessive disease causing severe disability. Ataxia refers to poor coordination and telangiectasia to small dilated blood vessels, both of which are hallmarks of the disease.
A-T affects many parts of the body:
Symptoms most often first appear in early childhood (the toddler stage) when children begin to walk. Though they usually start walking at a normal age, they wobble or sway when walking, standing still or sitting, and may appear almost as if they are drunk. In late pre-school and early school age, they develop difficulty moving their eyes in a natural manner from one place to the next (oculomotor apraxia). They develop slurred or distorted speech, and swallowing problems. Some have an increased number of respiratory tract infections (ear infections, sinusitis, bronchitis, and pneumonia). Because not all children develop in the same manner or at the same rate, it may be some years before A-T is properly diagnosed. Most children with A-T have stable neurologic symptoms for the first 4–5 years of life, but begin to show increasing problems in early school years.
A-T is caused by a defect in the ATM gene, which is responsible for managing the cell’s response to multiple forms of stress including double-strand breaks in DNA. In simple terms, the protein produced by the ATM gene recognizes that there is a break in DNA, recruits other proteins to fix the break, and stops the cell from making new DNA until the repair is complete.
There is substantial variability in the severity of features of A-T among affected individuals, and at different ages. The following symptoms or problems are either common or important features of A-T:
Many children are initially misdiagnosed as having ataxic cerebral palsy. The diagnosis of A-T may not be made until the preschool years when the neurologic symptoms of impaired gait, hand coordination, speech and eye movement appear or worsen, and the telangiectasia first appear. Because A-T is so rare, doctors may not be familiar with the symptoms, or methods of making a diagnosis. The late appearance of telangiectasia may be a barrier to the diagnosis. It may take some time before doctors consider A-T as a possibility because of the early stability of symptoms and signs.
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