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Severe microcephaly

Gene: OLA1

Amber List (moderate evidence)
OLA1 (Obg like ATPase 1)
EnsemblGeneIds (GRCh38): ENSG00000138430
EnsemblGeneIds (GRCh37): ENSG00000138430
OMIM: 611175, Gene2Phenotype
OLA1 is in 3 panels

1 review

Ida Ertmanska (Genomics England Curator)

Green List (high evidence)

Comment on list classification: In a cohort of 14 patients with biallelic OLA1 variants, there are 2 patients reported with severe microcephaly, 2 with likely severe microcephaly, and 2 others with borderline severe microcephaly. Hence, this gene should be promoted to Green at the next update.
Created: 1 Apr 2026, 10:35 a.m. | Last Modified: 1 Apr 2026, 10:35 a.m.
Panel Version: 8.43
PMID: 41887223 Alabdi et al., 2026
14 individuals from 9 families reported with homozygous loss of function variants in OLA1 with a phenotype characterised by a neurodevelopmental condition with connective tissue disorder.
All 14 individuals presented with intellectual disability / psychomotor delay. Seizures were reported in unrelated 6 individuals. Joint hypermobility was noted in 13/13 patients, 5 of them had skin laxity. 6 individuals had scoliosis or kyphoscoliosis. Several patients were diagnosed with Ehlers-Danos syndrome.
Severe / borderline severe microcephaly was noted in 6 individuals from 4 unrelated families (severity details: -4.49 SD, -4.6SD, -2.5SD, -2.54SD, and 2 microcephalic sibs in Family 8 with HC 46cm at 10 years & HC 45cm at 9 years - both estimated to be under -3SD based on PMID: 20304425)

Functional evidence: C. elegans model with knock-in protein-truncating variants showed behavioural abnormalities (reduced bending, no response to touch), and reduced axon numbers in GABAergic neurons.
Variant in family 1 (p.Arg143Ter) was shown to cause complete loss of OLA1 protein on Western blot; RT-PCR was supportive of NMD taking place. Splice variant seen in Family 8 (c.728+5G>A) was demonstrated to cause exon 7 skipping.

OLA1 is not yet associated with a phenotype in OMIM (accessed 1st April 2026).
Sources: Literature
Created: 1 Apr 2026, 10:12 a.m. | Last Modified: 1 Apr 2026, 10:43 a.m.
Panel Version: 8.43

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Ehlers-Danlos syndrome, hypermobility type, MONDO:0007523; neurodevelopmental disorder,MONDO:0700092; microcephaly, MONDO:0001149

Publications

Created: 1 Apr 2026, 10:12 a.m.
Last Modified: 1 Apr 2026, 10:43 a.m.
Panel version: 8.42

Details

Mode of Inheritance
BIALLELIC, autosomal or pseudoautosomal
Sources
  • Expert Review Amber
  • Literature
Phenotypes
  • Ehlers-Danlos syndrome, hypermobility type, MONDO:0007523
  • neurodevelopmental disorder,MONDO:0700092
  • microcephaly, MONDO:0001149
Tags
Q2_26_promote_green
OMIM
611175
Clinvar variants
Variants in OLA1
Penetrance
None
Publications
Panels with this gene

History Filter Activity

1 Apr 2026, Gel status: 2

Removed Tag, Added Tag

Ida Ertmanska (Genomics England Curator)

Tag Q1_26_promote_green was removed from gene: OLA1. Tag Q2_26_promote_green tag was added to gene: OLA1.

1 Apr 2026, Gel status: 2

Entity classified by Genomics England curator

Ida Ertmanska (Genomics England Curator)

Gene: ola1 has been classified as Amber List (Moderate Evidence).

1 Apr 2026, Gel status: 1

Created, Added New Source, Added Tag, Set mode of inheritance, Set publications, Set Phenotypes

Ida Ertmanska (Genomics England Curator)

gene: OLA1 was added gene: OLA1 was added to Severe microcephaly. Sources: Literature Q1_26_promote_green tags were added to gene: OLA1. Mode of inheritance for gene: OLA1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: OLA1 were set to 41887223 Phenotypes for gene: OLA1 were set to Ehlers-Danlos syndrome, hypermobility type, MONDO:0007523; neurodevelopmental disorder,MONDO:0700092; microcephaly, MONDO:0001149 Review for gene: OLA1 was set to GREEN