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Friedreich's Ataxia

Overview

Friedreich’s Ataxia (also known as FA or Friedreich Ataxia) is a rare inherited genetic disease that causes movement problems and nervous system damage [1].  Over time, the disease leads to degeneration in the spinal cord, peripheral nerves and cerebellum (the part of the brain that controls synchronization and balance) and causes impaired muscle coordination (ataxia) that gets worse over time [2].

Poor coordination is one of the first noticeable features of FA.  The neurological degeneration caused by the disease results in unsteady movements, impaired sensory function, and even the loss of speech.   Affected individuals can also develop heart problems, diabetes, or curvature of the spine.  However, the disorder does not affect cognitive ability [1].

Though rare, FA affects 1 in every 50,000 people and is the most common form of hereditary ataxia in the US [1].

Genetic Cause of FA

FA is characterized by abnormal copies of the gene FXN, which leads to a decrease in production of a protein called frataxin. In a normal copy of the FXN gene, a triplet sequence of DNA called GAA repeats 7-22 times.  However, in an affected cell, GAA can repeat up to a thousand times.  Frataxin is found in the energy-producing parts of the cell and a decrease in it can cause poor iron regulation, impaired cellular energy production, and a buildup of toxic byproducts. [1]

 FA is an inherited condition that is passed down in an autosomal recessive pattern, meaning that both copies of the gene – one from each parent - must show mutations for the disease to develop [2].  However, a person with only one abnormal copy of the gene is a carrier and will not show symptoms.  About 1 in 90 Americans with European ancestry carry the gene mutation.

 

Diagnosis & Prognosis

People with Friedreich’s Ataxia begin to experience symptoms between 5 and 15 years, though they can appear in adulthood.  Poor coordination and movement impairments are usually the first symptoms to appear and within 10 years of the first symptoms, affected individuals typically require the use of a wheelchair [2].

FA requires a clinical examination to diagnose, including a physical exam, medical history check, and a genetic screening.  Other methods of aiding an FA diagnosis include [1];

  • electromyogram (EMG) - measures the electrical activity of muscle cells

  • rve conduction studies - measures the speed with which nerves transmit impulses

  • electrocardiogram (also called EKG or ECG) - shows the electrical activity or beat pattern of the heart

  • echocardiogram - records the position and motion of the heart muscle

  • blood tests to check for elevated glucose levels and vitamin E levels

  • magnetic resonance imaging (MRI) or computed tomography (CT) scans - provides brain and spinal cord images