NOP56 Repeat Expansion Testing

Description

Pathogenic hexanucleotide GGCCTG repeat expansions within the first intron of the NOP56 gene have been associated with autosomal dominant spinocerebellar ataxia 36 (SCA36). The pathogenic repeat expansions have been shown to lead to formation of RNA foci that sequester important RNA binding proteins, which can interfere with the normal cellular function of neurons ¹.

Pathogenicity is dependent upon GGCCTG repeat length according to the following ranges ^2-4:

*Rare cases of SCA36 associated with repeat sizes in this range have been reported and might be associated with lower penetrance or milder phenotypes ^2,4.

Note: As SCA36 is typically adult onset, NOP56 repeat expansions are not reported in minors in comprehensive analyses.