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Hereditary ataxia with onset in adulthood

STR: FGF14_GAA

Amber List (moderate evidence)

Chromosome: 13
GRCh38 Position: 101710804-102402443
Repeated Sequence: GAA
Normal Number of Repeats: < 249
Pathogenic Number of Repeats: = or > 300

FGF14 (fibroblast growth factor 14)
EnsemblGeneIds (GRCh38): ENSG00000102466
EnsemblGeneIds (GRCh37): ENSG00000102466
OMIM: 601515, Gene2Phenotype
FGF14 is in 11 panels

2 reviews

Eleanor Williams (Genomics England Curator)

After NHS Genomic Medicine Service consideration, the rating of this STR has not been changed and remains Amber.

Comments from review:
Agree that the expansion is likely disease causing. However only a small number of cases have been used to define the number of repeats that could be considered pathogenic. Would recommend that more cases should be identified to better define the pathogenic repeat lengths of this STR. Perhaps study in 100,000 Genomes and GMS data would provide additional cases.

Agree that alleles >250 rpts are of interest and those >300 likely to be diagnostic but concerned that Expansion Hunter will not be able to provide accurate sizing beyond a threshold well below this (~100 repeats). See Supplementary figure S2 of PMID 36493768 for an illustration of this. Can ExpansionHunterDeNovo do better using paired IRRs (PMID PMID: 32345345), or can Expansion Hunter be adapted to factor-in paired IRRs to give a better prediction of expansion size? PCR based assays will also be essential for confirmation and sizing of any repeats detected, not currently available diagnostically to our knowledge.
Created: 27 Oct 2023, 11:29 a.m. | Last Modified: 27 Oct 2023, 11:29 a.m.
Panel Version: 4.26
Comment on list classification: Promoting to amber but there is sufficient evidence to promote to green following GMS review, and configuration in the Rare Disease analysis pipeline. GMS expert review is required to confirm that the normal and pathogenic thresholds set are appropriate.
Created: 1 Mar 2023, 10:43 p.m. | Last Modified: 12 Jun 2023, 10:19 p.m.
Panel Version: 4.12
The FGF14 gene is associated with Spinocerebellar ataxia 27A (#193003) (SNVs) and Spinocerebellar ataxia 27B, late-onset (#620174) (repeat expansion) in OMIM.

PMID: 36516086 - Pellerin et al 2023 - in 6 French Canadian patients with autosomal dominant late-onset cerebellar ataxia (LOCA), from 3 families (2 from each family) were analysed and a deep intronic GAA repeat expansion in FGF14 was identified, as well as in 15 affected relatives. 250 GAA repeats was the smallest expansion in any affected family member. They also determined FGF14_GAA repeat expansion size of 66 French Canadian, 228 German, 20 Australian, and 31 Indian index patients plus 408 persons without ataxia. There was significant association between FGF14 (GAA)≥250 expansions and LOCA in the French Canadian series (P<0.001) and in the German series, P<0.001) The high proportion of French Canadian patients carrying the FGF14 expansion may correspond to a founder effect in this population.

PMID: 36493768 - Rafehi et al 2023 - 4/95 (4.2%) of Australian individuals with adult-onset ataxia were identified to have repeat expansions (GAA)>300 in FGF14 and a further 9 individuals with (GAA)>250. No control subjects had (GAA)>300 and only 0.6% of control subjects had a pure (GAA)>250. In a German validation cohort, 9/104 (8.7%) of affected individuals had (GAA)>335 and a further 6 had (GAA)>250. Again no control subjects had (GAA)>335 and 5.3% control subjects had (GAA)>250. They conclude that (GAA)>335 are disease causing and fully penetrant while (GAA)>250 is likely pathogenic with reduced penetrance.
Created: 1 Mar 2023, 10:35 p.m. | Last Modified: 1 Mar 2023, 10:35 p.m.
Panel Version: 3.12

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown

Phenotypes
Spinocerebellar ataxia 27B, late-onset, OMIM:620174

Publications

Philip Twiss (Cambridge University Hospitals)

I don't know

New STR disease loci reported to account for significant number of dominant late onset ataxia cases. Not current standard of care therefore no diagnostic accredited PCR assays available currently in UK.
Sources: Literature
Created: 15 Feb 2023, 12:56 p.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
Late-onset cerebellar ataxia; Episodic features; Nystagmus

Publications

Details

Name
FGF14_GAA
Chromosome
13
GRCh38 Coordinates
101710804-102402443
Repeated Sequence
GAA
Normal Number of Repeats: <
249
Pathogenic Number of Repeats: = or >
300
Mode of Inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Sources
  • Expert Review Amber
Phenotypes
  • Spinocerebellar ataxia 27B, late-onset, OMIM: 620174
Tags
watchlist
OMIM
601515
Clinvar variants
Variants in FGF14
Penetrance
Complete
Publications

History Filter Activity

27 Oct 2023, Gel status: 2

Removed Tag, Removed Tag, Removed Tag, Added Tag

Eleanor Williams (Genomics England Curator)

Tag Q1_23_promote_green was removed from STR: FGF14_GAA. Tag Q1_23_expert_review was removed from STR: FGF14_GAA. Tag Q1_23_NHS_review was removed from STR: FGF14_GAA. Tag watchlist tag was added to STR: FGF14_GAA.

7 Sep 2023, Gel status: 2

Set Phenotypes

Sarah Leigh (Genomics England Curator)

Phenotypes for STR: FGF14_GAA were changed from Late-onset cerebellar ataxia; Episodic features; Nystagmus; Spinocerebellar ataxia 27B, late-onset, OMIM:620174 to Spinocerebellar ataxia 27B, late-onset, OMIM: 620174

7 Sep 2023, Gel status: 2

Set publications

Sarah Leigh (Genomics England Curator)

Publications for STR: FGF14_GAA were set to 36516086; 36493768

1 Mar 2023, Gel status: 2

Set Phenotypes

Eleanor Williams (Genomics England Curator)

Phenotypes for STR: FGF14_GAA were changed from Late-onset cerebellar ataxia; Episodic features; Nystagmus to Late-onset cerebellar ataxia; Episodic features; Nystagmus; Spinocerebellar ataxia 27B, late-onset, OMIM:620174

1 Mar 2023, Gel status: 2

Set publications

Eleanor Williams (Genomics England Curator)

Publications for STR: FGF14_GAA were set to PMID: 36516086

1 Mar 2023, Gel status: 2

Entity classified by Genomics England curator

Eleanor Williams (Genomics England Curator)

Str: fgf14_gaa has been classified as Amber List (Moderate Evidence).

1 Mar 2023, Gel status: 0

Added Tag, Added Tag, Added Tag

Eleanor Williams (Genomics England Curator)

Tag Q1_23_promote_green tag was added to STR: FGF14_GAA. Tag Q1_23_expert_review tag was added to STR: FGF14_GAA. Tag Q1_23_NHS_review tag was added to STR: FGF14_GAA.

15 Feb 2023, Gel status: 0

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

Philip Twiss (Cambridge University Hospitals)

STR: FGF14_GAA was added STR: FGF14_GAA was added to Hereditary ataxia - adult onset. Sources: Literature Mode of inheritance for STR: FGF14_GAA was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for STR: FGF14_GAA were set to PMID: 36516086 Phenotypes for STR: FGF14_GAA were set to Late-onset cerebellar ataxia; Episodic features; Nystagmus Penetrance for STR: FGF14_GAA were set to Complete Review for STR: FGF14_GAA was set to AMBER