GeneDx Expands Its Genetic Tests to Adult Forms of Ataxias

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Genetic tests

GeneDx has expanded its list of genetic tests to include the analysis of expansion repeats that underlie adult-onset ataxias, including Friedreich’s ataxia (FA), spinocerebellar ataxia, and other forms of inherited ataxias.

With this expansion, GeneDx — a subsidiary of BioReference Laboratories, part of the OPKO Health company — is now offering affordable genetic tests for both childhood and adult ataxias.

“GeneDx has a deep clinical knowledge of the ataxias and related movement disorders, gained from our long history and industry-leading development of neurogenetic testing,” Sean Hofherr, PhD, executive vice president and CLIA laboratory director of GeneDx, said in a press release.

“Expanding our menu to include adult-onset ataxias, in addition to the existing portfolio for childhood-onset ataxias, underscores GeneDx’s commitment to rare disease identification as well as filling an unmet need for patients and providers, alike,” Hofherr added.

FA is an inherited form of ataxia that is caused by mutations in the FXN gene, which has the instructions for the production of frataxin, a protein required for the proper functioning of nerves and muscle cells. As a result, people with FA develop difficulties in walking due to loss of muscle coordination (ataxia).

Disease-causing mutations in FA and other ataxias often involve an abnormal expansion of a portion of the gene. In FA, these mutations cause the repeat of three nucleotides — the building blocks of DNA — called GAA. Thus, the genetic tests for diagnosing FA assess the length of the GAA expansion, which can go as high as 1,700 repeats.

Typically, a high number of repeats is associated with disease manifestations in the first decade of life, and patients with a low number of GAA repeats tend to have their first symptoms later in life, during adulthood.

However, only a limited number of labs perform specialized genetic tests that examine nucleotide repeat expansions. There is a particular shortage of testing for adult-onset ataxias, meaning that patients experience long waiting times before receiving their results and have high out-of-pocket costs.

“Individuals with ataxia need more diagnostic testing options for genetic forms of the disease,” said Amanda Lindy, PhD, director of neurogenetics for GeneDx. “Historically, genetic testing for ataxia has been limited, creating a barrier for some individuals to obtain testing.”

GeneDx has expanded its list of comprehensive and affordable genetic tests to include most genes involved in pediatric- and adult-onset ataxias. Patients and healthcare professionals can order genetic analysis of repeat expansions for a single gene or multiple genes.

This can be accompanied by a more general genetic profile, called an ataxia Xpanded panel, that looks for other mutations in common ataxia-related genes.

This strategy improves the accuracy of the diagnosis, especially for clinical cases in which a disease diagnosis cannot be established solely on clinical symptoms, expanding the genetic analysis to a panel of genes that are most likely relevant to the patient’s clinical presentation.

“GeneDx’s expanded test offerings provide the flexibility of ordering single or multi-gene repeat expansion analyses, concurrently or reflexively, with a phenotypically driven Xpanded panel or an exome. Thus covering the broadest possible differential, delivering more answers to patients and their families, and enabling precision medical management,” said Lindy.