chr16-81354496-T-C

Position:

• chr16-81354496-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_022041.4(GAN):​c.374T>C​(p.Leu125Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,794 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 Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GAN NM_022041.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.67

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.95
• PP5: Variant 16-81354496-T-C is Pathogenic according to our data. Variant chr16-81354496-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 465396.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GAN	NM_022041.4	c.374T>C	p.Leu125Ser	missense_variant	3/11	ENST00000648994.2	NP_071324.1
GAN	NM_001377486.1	c.-266T>C		5_prime_UTR_variant	2/10		NP_001364415.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GAN	ENST00000648994.2	c.374T>C	p.Leu125Ser	missense_variant	3/11		NM_022041.4	ENSP00000497351	P1
GAN	ENST00000674788.1	n.499T>C		non_coding_transcript_exon_variant	3/3
GAN	ENST00000648349.2	c.*82T>C		3_prime_UTR_variant, NMD_transcript_variant	2/10			ENSP00000498114
GAN	ENST00000650388.1	c.168-2289T>C		intron_variant, NMD_transcript_variant				ENSP00000498081

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461794 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727214

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Giant axonal neuropathy 1 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 15, 2023

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. 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 expected to disrupt GAN protein function. ClinVar contains an entry for this variant (Variation ID: 465396). This missense change has been observed in individual(s) with clinical features of giant axonal neuropathy (Invitae). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces leucine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 125 of the GAN protein (p.Leu125Ser). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.44
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.91	D;D
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.86	.;D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.95	D;D
MetaSVM	Uncertain	0.79	D
MutationAssessor	Pathogenic	3.4	M;M
MutationTaster	Benign	0.98	D
PrimateAI	Pathogenic	0.85	D
Sift4G	Uncertain	0.054	T;.
Polyphen		1.0	D;D
Vest4		0.99
MVP		0.93
MPC		0.37
ClinPred		0.99	D
GERP RS		5.7
Varity_R		0.89
gMVP		0.91

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: rs1555511093; hg19: chr16-81388101;