rs766155831

Variant names:

• chr16-81365357-G-A
• rs766155831
• NM_022041.4:c.1381G>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 5P and 1B. PM1 PM2 PP2 BP4

The NM_022041.4(GAN):​c.1381G>A​(p.Ala461Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,880 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A461V) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GAN NM_022041.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 5.89
• Publications: 0 publications found

Genes affected

GAN (HGNC:4137): (gigaxonin) This gene encodes a member of the cytoskeletal BTB/kelch (Broad-Complex, Tramtrack and Bric a brac) repeat family. The encoded protein plays a role in neurofilament architecture and is involved in mediating the ubiquitination and degradation of some proteins. Defects in this gene are a cause of giant axonal neuropathy (GAN). [provided by RefSeq, Oct 2008]

GAN Gene-Disease associations (from GenCC):

• giant axonal neuropathy 1

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Labcorp Genetics (formerly Invitae), ClinGen, Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 7 uncertain in NM_022041.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 11 curated pathogenic missense variants (we use a threshold of 10). The gene has 3 curated benign missense variants. Trascript score misZ: -2.0288 (below the threshold of 3.09). GenCC associations: The gene is linked to giant axonal neuropathy 1.
• BP4: Computational evidence support a benign effect (MetaRNN=0.41379857).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GAN	NM_022041.4	c.1381G>A	p.Ala461Thr	missense_variant	Exon 9 of 11	ENST00000648994.2	NP_071324.1
GAN	NM_001377486.1	c.742G>A	p.Ala248Thr	missense_variant	Exon 8 of 10		NP_001364415.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GAN	ENST00000648994.2	c.1381G>A	p.Ala461Thr	missense_variant	Exon 9 of 11		NM_022041.4	ENSP00000497351.1

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251486 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461880 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727244

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1112006

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 30

Alfa AF: 0.0000312 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Dec 31, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1381G>A (p.A461T) alteration is located in exon 9 (coding exon 9) of the GAN gene. This alteration results from a G to A substitution at nucleotide position 1381, causing the alanine (A) at amino acid position 461 to be replaced by a threonine (T). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Giant axonal neuropathy 1 Uncertain:1

Jul 30, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 461 of the GAN protein (p.Ala461Thr). This variant is present in population databases (rs766155831, gnomAD 0.0009%). This variant has not been reported in the literature in individuals affected with GAN-related conditions. ClinVar contains an entry for this variant (Variation ID: 581073). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt GAN protein function with a negative predictive value of 80%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

not provided Uncertain:1

Dec 17, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are a common cause of disease and they are underrepresented in the general population; In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This variant is associated with the following publications: (PMID: 27023907) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.74
BayesDel_addAF	Uncertain	0.061	T
BayesDel_noAF	Benign	-0.15
CADD	Pathogenic	29
DANN	Pathogenic	1.0
DEOGEN2	Benign	0.36	T;T
Eigen	Uncertain	0.47
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.94	.;D
M_CAP	Benign	0.018	T
MetaRNN	Benign	0.41	T;T
MetaSVM	Benign	-0.66	T
MutationAssessor	Benign	0.34	N;N
PhyloP100		5.9
PrimateAI	Uncertain	0.76	T
Sift4G	Uncertain	0.043	D;.
Polyphen		0.93	P;P
Vest4		0.71
MutPred		0.44		Gain of phosphorylation at A461 (P = 0.0786);Gain of phosphorylation at A461 (P = 0.0786);
MVP		0.68
MPC		0.41
ClinPred		0.82	D
GERP RS		5.7
Varity_R		0.10
gMVP		0.45
Mutation Taster		=84/16	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs766155831; hg19: chr16-81398962;