Babies born in Western Australia are being screened for a genetic neuromuscular condition that can be life-threatening.

From Monday a check for spinal muscular atrophy will be included in the heel-prick test conducted on all newborns.

The condition is inherited and affects nerves leading to muscles, blocking messages from the brain. Over time, the muscles become weaker and waste away.

Babies born with the condition initially appear normal but often don't reach milestones like sitting or rolling in early infancy, are floppy and have progressive weakness and loss of motor function.

While there is no known cure, early therapy can provide dramatic improvements in life span and quality of life.

"We know early intervention leads to better health outcomes for newborns and their families, which is why the newborn heel-prick test is so important," Health Minister Amber-Jade Sanderson said.

"Expanding the heel-prick test to include spinal muscular atrophy will save lives and prevent long-term issues."

About 35,000 babies born in WA are screened for some 25 serious disorders. Of them, about one in 1000 has a congenital condition that would otherwise go undetected.

The test is performed when a baby is two to three days old. A health professional pricks the heel, collecting blood on a special card which is dried and sent to a laboratory for analysis.