Causes for Fragile X Syndrome

The cause of the Fragile X syndrome is the change in a gene, which results in Fragile X Mental Retardation 1 gene (also referred to as FMR1 gene), which is usually found on the X chromosome.

How the effect on single gene affect the production of protein in the body?

These genes present on the chromosome contain the information that is used by some other parts of the brain cells to produce proteins. Each protein is very important as they perform a specific function and are, thus, called the building blocks of the body. They help in developing the structure of your tissues and organs and also for your body functions.

How does the change in a single gene effect?

Every single gene has the information for the production of at least one protein. Thus, when the information is changed, the cell stops the production of that protein. As a result, the lack of protein shows many effects on the different parts of the body. Thus, Fragile X occurs due to the FMR1 gene, which is unable to produce the adequate amount of usable FMRP or Fragile X Mental Retardation Protein.

Which factor determines the effects of Fragile X?

The factor which is helpful in determining the severity of the Fragile X individual is the FMRP amount in the body. Thus, when an individual has FMRP in normal levels, then they may show no or mild symptoms, but an individual with less or no FMRP may show extremely severe symptoms.


Scientists are doing continuous study on Fragile X syndrome. One recent study in mice revealed that some cells process the brain cells in excess that are used to communicate with one another; thus it leads them to communicate either in excess or in an inappropriate way. Researchers believe that these FMRP levels may regulate the communication and control it. Scientists are hopeful about the similar function of FMRP in humans.

Mental retardation causes

Mental retardation is commonly associated with 500 conditions or more. Thus, the most commonly associated genetic causes among these are:

  • Down syndrome

    This is caused by  an error within the chromosome number.

  • Fragile X syndrome

    This is caused by a repetitive coding in the genetic code, which leads to the lack of protein production. These proteins are needed by the brain cells to function properly. Lack of these proteins causes various disorders.

  • Phenylketonuria (PKU)

    PKU is caused by a single gene error that is helpful in making a defective enzyme.

  • Other causes

    Some of the mental retardation causes can occur during the pregnancy, which includes the mother’s exposure to poisons, diseases, such as rubella, and excessive alcohol use, etc.

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