The syndrome has a higher prevalence in females and typically appears between 5-15 years of age.

In most of the families reported so far, tetra-amelia syndrome appears to have an autosomal recessive pattern of inheritance.

The syndrome appears to involve the spinal cord: specifically, the anterior horn cells subserving the affected muscles are often damaged.

This syndrome appears to affect males mostly.

Schimmelpenning syndrome appears to be sporadic rather than inherited, in almost all cases.

A syndrome called sudden unexpected death in epilepsy patients, or Sudep, appears to be much more common than previously thought.

The syndrome can appear dramatically or develop unnoticed.

The data is inconclusive; however the syndrome does appear to exist as a manifestation of all the internal and external stress crews in space must face.

In most affected individuals, Angelman syndrome appears to occur spontaneously (sporadically) for unknown reasons.

Catel-Manzke syndrome usually appears to occur randomly, for unknown sporadic reasons.