Invitae Corporation, one of the fastest growing genetic information companies, has announced the availability of a new genetic test for the diagnosis of Spinal Muscular Atrophy (SMA), a neuromuscular disease that is one of the leading lethal genetic disorders among infants as well as a significant cause of progressive neuromuscular disease in childhood. The new test, announced during the American College of Medical Genetics (ACMG) Annual Clinical Genetics Meeting, features a novel, custom methodology that offers significant improvements over current testing approaches.

SMA is an autosomal recessive disorder and the second leading genetic disease in infancy behind cystic fibrosis affects. SMA affects approximately one in every 10,000 infants, while one in 50 people is a carrier for the disorder. The majority of SMA cases are caused by loss of the gene SMN1, with variation in the number of copies of related gene, SMN2, playing a role in mitigating the severity of the disease. Loss of SMN1 results in the absence of a protein necessary for the normal function of nerves governing movement. Without adequate nerve function, patients with SMA experience progressive muscle weakness and atrophy, impacting the ability to crawl, sit, or stand and eventually to breathe or swallow.

Accurate testing of both genes is critical for the diagnosis and treatment of SMA. Testing for the absence of functional SMN1 is the basis of diagnosis and can distinguish the condition from other neuromuscular diseases such as muscular dystrophy. Understanding the number of copies of the SMN2 gene can provide prognostic information and help guide therapeutic choices and clinical trial participation. However, due to the similarities between the two genes, testing is technically challenging and reliably accurate tests have not previously been widely available.

"Determining SMN2 copy number accurately has, in the past, been a challenge. Improvement in the SMN2 copy number assay will provide better diagnostic and prognostic information about SMA patients that will guide clinicians with appropriate disease management," said Perry Shieh, MD, associate professor and director of the neuromuscular program at the University of California Los Angeles.

Invitae's unique approach leverages advanced next generation sequencing and a customized bioinformatics solution to accurately identify sequence changes and copy number changes in both genes from a single test. Analysis of SMN1 and SMN2 is now available from Invitae as a stand-alone test, and it has been added to a number of the company's comprehensive neuromuscular and neuropathy panels, allowing physicians the ability to test for SMA alongside a number of other neurological disorders for no additional cost.

"In addition to the use of the Invitae SMA test in the diagnosis of infants and children with early onset neuromuscular disease, the recent development of new therapies directed at SMA is leading to the possible inclusion of SMN1 testing in universal newborn screening panels, which will mean in turn that having an accurate, cost-effective confirmatory test is essential," said Robert Nussbaum, MD, chief medical officer at Invitae. "We're proud to bring this advancement in testing to the SMA community."