GLS Repeat Expansion Testing

Description

Pathogenic GCA repeat expansions within the 5′ untranslated regions of the GLS gene, which may be biallelic or compound heterozygous with a different pathogenic variant, have been associated with autosomal recessive global developmental delay, progressive ataxia, and elevated glutamine (GDPAG). The pathogenic repeat expansions are thought to cause a repressive heterochromatin state which reduces GLS transcription.

Pathogenicity is dependent upon GCA repeat length according to the following ranges ¹: