What is the Difference Between Fragile X and Down Syndrome?
🆚 Go to Comparative Table 🆚Fragile X syndrome (FXS) and Down syndrome (DS) are two of the most prevalent genetic causes of intellectual disability. They share some similarities, such as disturbances in how the nervous system develops and communicates, as well as deficits in expressive language ability and increased rates of Autism Spectrum Disorder (ASD), seizure disorders, and other mental health disorders. However, there are significant differences between the two conditions:
- Causes: DS is caused by an extra copy of all or part of chromosome 21, while FXS is an inherited disorder caused by an expansion of the sequence of trinucleotide (CGG) repeats included in the fragile X mental retardation 1 (FMR1) gene located on the X chromosome.
- Genetic Inheritance: FXS is an inherited genetic disorder, with affected individuals typically having a family history of the condition. DS, on the other hand, is usually not inherited and occurs randomly during the formation of reproductive cells in the parents.
- Molecular Pathways: Despite their distinct genetic causes, a shared molecular pathway for intellectual disability has been identified in both FXS and DS. This pathway is involved in the regulation of how nerve cells develop and communicate.
- Molecular Mechanisms: In DS, the extra genetic material leads to increased protein expression through increased gene dosage, while in FXS, the loss of translational repression results in increased protein expression.
In summary, while Fragile X syndrome and Down syndrome share some similarities in their effects on intellectual disability and related conditions, they have distinct genetic causes and molecular pathways.
Comparative Table: Fragile X vs Down Syndrome
Fragile X syndrome (FXS) and Down syndrome (DS) are two of the most prevalent genetic causes of intellectual disability. Both syndromes share certain characteristics, such as deficits in expressive language ability and increased rates of Autism Spectrum Disorder (ASD), seizure disorders, and other mental health disorders. However, there are key differences between the two syndromes:
| Feature | Fragile X Syndrome | Down Syndrome |
|---|---|---|
| Cause | Mutation of the FMR1 gene in the X chromosome | Presence of an extra copy of the 21st chromosome |
| Diagnosis | Karyotype test (chromosome analysis) to confirm diagnosis | |
| Key Difference | Fragile X syndrome is due to a gene mutation, while Down syndrome is due to the presence of an extra copy of chromosome 21 | Intellectual disability triggers impaired cognitive development and daily lifestyle functions. Both syndromes may have similar symptoms, such as a lack of expressive language abilities, increased risk for autism spectrum disorder, seizure disorders, and other mental health disorders |
Despite the presence of intellectual disability and increased risk of communication impairment in both syndromes, there are important differences in their molecular causes and manifestations.
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- Mosaic Down Syndrome vs Down Syndrome
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- Williams Syndrome vs Down Syndrome
- Down Syndrome vs Edward Syndrome
- Genetic Disorders vs Chromosomal Disorders
- Monogenic Disorders vs Chromosomal Disorders
- Rett Syndrome vs Autism
- Autism vs Asperger’s Syndrome
- Autism Spectrum Disorder vs Intellectual Disability
- Mendelian vs Chromosomal Disorders
- Dwarfism vs Cretinism
- Genetic vs Congenital Disorders
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- Trisomy vs Triploidy
- XX vs XY Chromosomes
- X Linked Dominant vs X Linked Recessive