The Fragile X Syndrome DNA test determines how many of the CGG repeats are present in the FMR1 gene.
- 5 – 44 repeats. This individual is normal.
- 45 – 54 repeats. This individual carries the intermediate allele, which does not cause fragile X syndrome.
- 55 – 200 repeats. This individual carries the premutation allele. The premutation allele is not associated with fragile X syndrome. However, these individuals are at increased risk for tremor ataxia syndrome and infertility issues. Women in this range are considered at risk of having a child affected with fragile X syndrome.
- >200 repeats. This individual carries the full mutation. The full mutation allele causes fragile X syndrome.
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