ALS Survival is Linked to ATXN2 polyQ Intermediate Repeats, Study Shows

A new study on amyotrophic lateral sclerosis (ALS), entitled, “ATXN2 polyQ intermediate repeats are a modifier of ALS survival” published in Neurology by Dr. A. Chiò from the ALS Center, Department of Neuroscience, University of Torino in Italy, evaluated the rate of ATXN2 polyQ intermediate repeats in a group of ALS patients.

Amyotrophic lateral sclerosis (ALS) is an uncommon and progressive neurodegenerative disease of the motor neurons that causes paralysis of skeletal muscles. It is generally characterized by rapid irreversible progression and is usually fatal. The origins of ALS are mostly not understood, but previous studies have suggested that genetic and environmental risk factors also contribute to the development of ALS. The repeats of CAG in the ataxin 2 gene (ATXN2) of intermediate lengths have been identified as regulators of amyotrophic lateral sclerosis (ALS) susceptibility.

In this study, the research team examined a population-based group of 672 Italian patients with ALS for the rate of occurrence, and clinical features of ALS patients carrying an intermediate CAG repeat (encoding 27-33 glutamines, polyQ) of the gene ATXN2. They repeated the analysis in a group of 661 patients from an ALS Clinic Center at the Catholic University in Rome, Italy. The control group was comprised of age- and sex-matched individuals without any neurological condition.

The research team found that in the 672 ALS patients, the frequency of lengths longer than 31 polyQ ATNX2 repeats was considerably higher. The survival of the patients was negatively correlated with higher numbers of polyQ repeats, i.e. the odds of survival were less encouraging than those carrying shorter 31 repeats.

From these observations, the authors concluded that an intermediate-length of the polyQ repeat of the gene ATXN2 is associated with ALS survival. Therapies that could be designed or formulated to specifically target the ATXN2 gene may be a promising, untapped strategy to prevent ALS.

In other developments in the ongoing fight against ALS, a $30 million alliance between Biogen Idec and Columbia University Medical Center was formed to conduct research in genetics and to understand the underlying causes of several diseases such as amyotrophic lateral sclerosis (ALS). This new partnership may help identify new treatment approaches to address the largely unmet clinical needs of this disorder.