Undiagnosed metabolic disorders

STR: GLS_GCA

Green List (high evidence)

Comment on list classification: There are sufficient unrelated cases and supportive functional data for inclusion as diagnostic-grade.

However, detection of this 5' UTR triplet expansion must first be validated within the Genomics England pipeline. In the meantime, rating Red but will raise the STR for validation with the Rare Disease team.

Created: 19 Jan 2021, 11:47 a.m. | Last Modified: 19 Jan 2021, 11:47 a.m.

Panel Version: 2.50

GLS is associated with relevant phenotypes in OMIM, but currently is not in Gene2Phenoype.
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- PMID: 30970188 (2019) - Three unrelated cases who presented with an early-onset global developmental delay, progressive ataxia, and elevated levels of glutamine (MIM# 618412). One patient also showed cerebellar atrophy.

All 3 individuals harboured a large trinucleotide (GCA) repeat expansion in the 5' UTR (length: 680-1,500-copy repeats). The repeat expansion was found in homozygosity in 1 case, and occurred in compound heterozygosity with an SNV in the other two cases (missense and frameshift variant, respectively). Functional analysis showed the repeat expansion results in reduced expression and glutaminase deficiency.
Sources: Literature

Created: 19 Jan 2021, 11:46 a.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Global developmental delay, progressive ataxia, and elevated glutamine, OMIM:618412; Global developmental delay, progressive ataxia, and elevated glutamine, MONDO:0032733

Publications

• 30970188