Pediatric Pearls. More on the Newborn Screen: Spinal Muscular Atrophy (SMA)

October 3, 2023

This will be the last Pediatric Pearl post about the newborn screen. I hope I have convinced you that obtaining a newborn screen is of critical importance. Many of the conditions screened are important to pick up as soon as possible. Wherever you live, please check to see what conditions are screened for in your country/state/providence/province/area.

Don’t assume that the baby can’t have X because it was screened for. Things happen - maybe the collection was inadequate, maybe the parents refused, maybe your state doesn’t screen for X.

The state where I live, Massachusetts in the United States, screens for 35 conditions and then offers a screen for 8 more disorders in the pilot study group. No extra blood is needed for the pilot studies to be run. However, the parents do need to consent for the pilot studies to be conducted. I picked SMA to review because it is one of the conditions screened for in the pilot studies.

This is a newborn screen card. The infant’s heel was pricked and the blood has fully saturated the four circles at the right of the card. Note the check mark in the consent box in the upper right hand corner with the nurse’s initials, BM. This means the parents consented to have the pilot studies run.

What is SMA?

SMA stands for Spinal Muscular Atrophy. It is a rare genetic disease caused by the deletion or mutation of the survival motor neuron 1 (SMN1) gene. The SMN1 gene produces a protein, survival motor neuron (SMN) protein, that is critical for normal function of motor neurons. Patients with SMA have an insufficient amount of this SMN protein, which leads to a loss of motor neurons.

Motor neurons are nerve cells that control voluntary muscle movement. These cells are located in the spinal cord. If muscles are not receiving proper signals from the nerves, they weaken and shrink (or atrophy) from inactivity.