chr16-81356834-C-A

Position:

• chr16-81356834-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_022041.4(GAN):​c.683C>A​(p.Ser228Tyr) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,461,622 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 (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: GAN NM_022041.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.69

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 2 ACMG points.

• PM1: In a domain BACK (size 102) in uniprot entity GAN_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_022041.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24684548).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GAN	NM_022041.4	c.683C>A	p.Ser228Tyr	missense_variant	4/11	ENST00000648994.2	NP_071324.1
GAN	NM_001377486.1	c.44C>A	p.Ser15Tyr	missense_variant	3/10		NP_001364415.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GAN	ENST00000648994.2	c.683C>A	p.Ser228Tyr	missense_variant	4/11		NM_022041.4	ENSP00000497351.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251490 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: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461622 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727144

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: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

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

Labcorp Genetics (formerly Invitae), Labcorp

Dec 22, 2017

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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with GAN-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces serine with tyrosine at codon 228 of the GAN protein (p.Ser228Tyr). The serine residue is moderately conserved and there is a large physicochemical difference between serine and tyrosine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.20
BayesDel_addAF	Benign	-0.040	T
BayesDel_noAF	Benign	-0.29
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.42	T;T
Eigen	Benign	0.084
Eigen_PC	Uncertain	0.26
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.90	.;D
M_CAP	Benign	0.0069	T
MetaRNN	Benign	0.25	T;T
MetaSVM	Benign	-0.66	T
MutationAssessor	Benign	1.2	L;L
PrimateAI	Uncertain	0.52	T
Sift4G	Benign	0.38	T;.
Polyphen		0.044	B;B
Vest4		0.55
MutPred		0.33		Gain of phosphorylation at S228 (P = 0.0502);Gain of phosphorylation at S228 (P = 0.0502);
MVP		0.78
MPC		0.19
ClinPred		0.62	D
GERP RS		5.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.51
gMVP		0.36

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

Publications

LitVar

Other links and lift over

dbSNP: rs1301648787; hg19: chr16-81390439;