rs780427229

chr16-81365453-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_022041.4(GAN):c.1477G>A(p.Glu493Lys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000547 in 1,461,832 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. E493E) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: GAN NM_022041.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.64

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.938

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAN	NM_022041.4	c.1477G>A	p.Glu493Lys	missense_variant	9/11	ENST00000648994.2
GAN	NM_001377486.1	c.838G>A	p.Glu280Lys	missense_variant	8/10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAN	ENST00000648994.2	c.1477G>A	p.Glu493Lys	missense_variant	9/11		NM_022041.4	P1
GAN	ENST00000567335.1	n.35G>A		non_coding_transcript_exon_variant	1/2	3
GAN	ENST00000648349.2	c.*1185G>A		3_prime_UTR_variant, NMD_transcript_variant	8/10
GAN	ENST00000650388.1	c.*834G>A		3_prime_UTR_variant, NMD_transcript_variant	7/9

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251492 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135922

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461832 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727232

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.0000187

Gnomad4 NFE exome AF: 0.00000630

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 30

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Giant axonal neuropathy 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Apr 28, 2023

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. An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 533935). This missense change has been observed in individuals with giant axonal neuropathy (PMID: 30532362, 31655922). This variant is present in population databases (rs780427229, gnomAD 0.002%). This sequence change replaces glutamic acid, which is acidic and polar, with lysine, which is basic and polar, at codon 493 of the GAN protein (p.Glu493Lys). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.36
Cadd	Pathogenic	33
Dann	Pathogenic	1.0
DEOGEN2	Uncertain	0.53	D;D
Eigen	Uncertain	0.65
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Pathogenic	1.0	D
M_CAP	Uncertain	0.095	D
MetaRNN	Pathogenic	0.94	D;D
MetaSVM	Benign	-0.30	T
MutationAssessor	Benign	0.81	L;L
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.91	D
Sift4G	Pathogenic	0.0	D;.
Polyphen		1.0	D;D
Vest4		0.95
MutPred		0.81		Gain of methylation at E493 (P = 0.0071);Gain of methylation at E493 (P = 0.0071);
MVP		0.94
MPC		0.60
ClinPred		0.87	D
GERP RS		5.7
Varity_R		0.55
gMVP		0.92

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs780427229; hg19: chr16-81399058;