SPTAN1 is located at chromosome 9 and encodes α-ΙΙ spectrin. The patients with severe types show de novo in-frame variants at the last part of spectrin repeats. The variants of in-frame deletion/duplication in the last two spectrin repeats led severe phenotypes.
The truncating variants, microdeletion, or missense variants outside the last two spectrin are responsible for milder but complex phenotypes. The recurrent p.(Arg19Trip) variant is associated with spastic paraplegia and ataxia.
Currently, genetic diagnosis was made through comprehensive gene analysis. Only in-frame variants in the last two spectrin repeats could confirm the diagnosis of severe form of this gene variants.
SPTAN1