The disease is caused by a mutation in UBA1 gene and is passed in an X-linked recessive manner by carrier mothers to affected sons.

[citation needed] The disorder is usually fatal in infancy or early childhood due to progressive respiratory failure, although survival into teenage years has been reported.

[citation needed] XL-SMA is characterized by severe hypotonia and areflexia with loss of anterior horn cells in the spinal cord (i.e., lower motor neurons).

Components that may lead to a diagnosis include the presence of clinical symptoms,[7] evidence of degeneration, and analysis of family history.

In order to confirm this the most practical measures to take next are:[8] Following a diagnosis of the X-linked infantile spinal muscular atrophy it is recommended for the patient to go through further evaluations to alleviate symptoms as there is currently no known cure to SMAX2.

[8] Overall treatment aims at alleviating the symptoms and may include mechanical ventilation, feeding tube, gastrostomy, and orthopedic interventions.

[citation needed] X-linked spinal muscular atrophy type 2 is considered a rare disorder, and its prevalence is unknown.