A health ministry panel approved Wednesday the production and sale of a gene therapy for treating spinal muscular atrophy, a rare incurable disease that destroys muscle function through a decrease in motor neuron cells.

The health minister is expected to formally approve the drug, Zolgensma, by the end of March, with public health insurance coverage seen starting this summer.

The one-time-only gene therapy, developed by Swiss drug giant Novartis AG, will cover patients below 2 years old with abnormalities in their genes to make proteins necessary for maintaining motor nerves. Novartis estimates 15 to 20 children a year are likely to receive treatment using the drug in Japan.

In the therapy, proteins are created after the genes, carried by adeno-associated viruses, are delivered to motor nerves through intravenous drips. In an overseas clinical trial, all of the 15 severe SMA patients who used the therapy were able to live without an artificial ventilator. If no treatment is offered, about 75 percent of such patients are expected to die or need an artificial ventilator before they reach the age of 13.6 months.