What is a Repeat Expansion Ataxia Panel?

A Repeat Expansion Ataxia Panel is a specialized genetic testing tool designed to identify and characterize repeat expansion mutations associated with various types of ataxia. Additionally, this panel plays a crucial role in diagnosing hereditary ataxias caused by abnormal repeat sequences within specific genes.

What is an Repeat Expansion Ataxia?

Repeat Expansion Ataxia involves a type of genetic mutation known as repeat expansion, and this phenomenon associates with certain neurological disorders, including various forms of ataxia. To understand this concept, let’s break it down:

1. Ataxia: A neurological term that describes a group of disorders characterized by problems with coordination, balance, and voluntary muscle movements. People with ataxia often experience difficulties with walking, speaking, and performing fine motor tasks due to dysfunction in the cerebellum or other parts of the nervous system responsible for motor control.
2. Repeat Expansion: This occurs when specific sequences of nucleotides (the building blocks of DNA) are repeated multiple times in certain regions of the DNA. It is important to realize, that normally these repeat sequences exist with a stable number of repeats. However, in some genetic disorders, these repeat sequences can abnormally expand beyond a certain threshold.

What are Repeat Expansion Mutations?

In the context of ataxia, there are various repeat expansion mutations, each linked to unique genetic abnormalities and clinical presentations. To explain, let’s provide two well-known examples of ataxias caused by repeat expansion mutations:

• Friedreich’s ataxia: This is a progressive and degenerative neurological disorder caused by an abnormal expansion of a specific repeat sequence (GAA repeats) in the FXN gene. Furthermore, this repeat expansion leads to reduced production of a protein called frataxin, which is essential for mitochondrial function and iron homeostasis in cells. As a result, the mitochondrial dysfunction and oxidative stress contribute to the neurological symptoms of Friedreich’s ataxia.
• Spinocerebellar ataxias (SCAs): (SCAs) represent a group of inherited ataxias caused by repeat expansion mutations in different genes. Each type of SCA links to a specific gene and repeat sequence expansion. For instance, SCA type 1 results from an expansion of CAG repeats in the ATXN1 gene. Furthermore, repeat expansion leads to abnormal protein aggregation in brain cells, contributing to ataxia symptoms.

Benefits of the Repeat Expansion Ataxia Panel:

A Repeat Expansion Ataxia Panel is essential for diagnosing and categorizing hereditary ataxias accurately. Additionally, this panel aids in distinguishing between different ataxia forms by identifying specific repeat expansion mutations in associated genes.

Another primary benefit of a Repeat Expansion Ataxia Panel is its ability to offer a precise diagnosis. For instance, Healthcare providers can accurately identify the genetic cause of ataxia by analyzing the patient’s DNA for specific repeat expansion mutations.

Genes Tested in Panel:

• ATN1,
• ATXN1,
• ATXN10,
• ATXN2,
• ATXN3,
• ATXN7,
• ATXN8OS,
• BEAN1,
• CACNA1A,
• FXN,
• NOP56,
• PPP2R2B,
• TBP