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What is intellectual disability?

Intellectual disability (ID) is the result of a disturbance in human development that appears before the age of 18. It is characterised by a significant limitation in intellectual functioning and adaptive behaviour. In other words, the concept encompasses people whose cognitive resources are often less than expected for their chronological age.

What types of intellectual disabilities are there?

It affects about 1% of the population. It can present in mild or more severe forms.

Approximately 85% of cases are considered mild (between 50 and 70 IQ). These children are able to remain in the educational system, acquire some independence skills, receive training and even have professional activity.

● In cases of moderate intellectual disability, the IQ is between 35 and 50. They usually need a lot of attention and dedication, but can have a certain degree of autonomy.

Severe intellectual disability is found in cases with an IQ between 20 and 35. These people have reduced skills, little or no reading and numerical comprehension. They need continuous supervision.

● In cases of profound intellectual disability, the IQ is below 20.

What are the causes of intellectual disability?

There are many causes of ID. Some are genetic in origin. Others are the result of problems arising during birth or during the course of a childhood illness.

Genetic causes can be divided into syndromic and non-syndromic. This classification depends on whether the intellectual disability is present in isolation or accompanied by other clinical disorders.

The most frequent syndromes of genetic cause, which also affect intellectual development are:

● Down Syndrome

● Prader-Willi syndrome

● Angelman Syndrome

● Fragile X syndrome

● Lesch-Nyhan syndrome

● DiGeorge Syndrome

How is intellectual disability diagnosed?

Overall, only 25% of cases end up with an accurate and specific diagnosis. In this context, appropriate genetic testing can help to achieve an accurate diagnosis. In particular, genetic testing is recommended when the following conditions exist:

● There is a family history of intellectual or developmental disability, miscarriage or perinatal death.

● The disability is accompanied by characteristic phenotypic features.

● Other causes have been ruled out.

In Genosalut we evaluate more than 300 genetic alterations associated with mental retardation and autism.

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Intellectual disability: what is it, types, causes and diagnosis?
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