Fast Five Quiz: Acute Infantile Spinal Muscular Atrophy Type 1, or Werdnig-Hoffmann Disease

Stephen L. Nelson, Jr, MD, PhD


August 12, 2020

In most patients with SMA type 1, the cardiac system is not affected and ECGs are normal. Similarly, most patients have normal creatine kinase levels.

Prenatal and postnatal genetic tests are now commercially available. The US Department of Health and Human Services now recommends prenatal screening for SMA as part of their recommended uniform screening panel. Homozygous SMN1 gene deletion is 95% sensitive and almost 100% specific for the diagnosis of SMA. When SMA type 1 is suspected and patients do not have SMN1 gene deletion, SMN1 copy testing with sequencing of coding regions of SMN1 copy (if present) is suggested. Molecular genetic testing, which can detect the presence of a mutation in the survival motor neuron (SMN) gene, can be utilized to confirm a diagnosis of SMA.

Learn more about the workup for SMA type 1.


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