Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a fatal form of infantile neurodegenerative disease characterized by a selective death of motor neurons, the cells responsible for the signal transmission from the brain to the muscles. SMARD1 is characterized by respiratory distress, usually within the first year of life, and progressive muscle weakness leading to early degeneration of spinal cord motor neurons and axonal loss leading to muscular atrophy and death due to respiratory failure.

There is no cure for SMARD1, which is devastating both for patients and their families. Importantly, atypical presentation and milder cases are increasingly being recognized. This variability suggests the presence of genetic disease modifiers that can affect onset and severity by influencing various biological pathways.

The disease results from loss of function mutations in the gene encoding immunoglobulin μ-binding protein 2 (IGHMBP2) on chromosome 11q13. The human gene is implicated in DNA replication and RNA metabolism but its precise function in these processes and the reason for selective motor neuron death remain elusive, even if defects in RNA metabolism are well-established causes of neurodegenerative disorders.

A splice-site mutation in murine Ighmbp2 gene causes a neuromuscular disorder similar to the human disease in the mouse, which is used as animal model for SMARD1 disease studies.