Blood Test May Predict Treatment Response in SMA

Testing the biological effects of experimental drugs for spinal muscular atrophy (SMA) may soon be fairly easy and accurate, say researchers Louise Simard, of the University of Manitoba (Canada) in Winnepeg and colleagues.

A research team that included MDA-supported Kathryn Swoboda at the University of Utah announced in the Feb. 6 issue of Neurology that it has developed a method for measuring full-length SMN, the protein needed in SMA, from a blood sample.

Experimental treatments for SMA aim to increase the output of full-length SMN protein from genes known as SMN2, which normally make very little of it. Functional SMN1 genes, which SMA patients lack, are the normal source of full-length SMN.

In general, the more copies of the SMN2 genes a person without functional SMN1 genes has (the number varies), the less severe his SMA disease will be.

Measuring actual levels of full-length SMN protein or full-length SMN RNA (final genetic instructions for the protein) could be a more accurate way of predicting disease severity than simply counting SMN2 genes, the researchers say, and it might also be used to measure a patient’s response to treatment.