Genetic Variant NAPB:p.Ser77Asn (chr20-23397137-C-T) – ACMG Classification: Likely_benign (-2 pts)

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_022080.3(NAPB):c.230G>A(p.Ser77Asn) variant causes a missense change. The variant allele was found at a frequency of 0.0000124 in 1,613,586 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 14/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: 𝑓 0.000085 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000048 ( 1 hom. )

Consequence

NAPB
NM_022080.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 6.01

Publications

0 publications found

Variant links:

Genes affected

NAPB (HGNC:15751): (NSF attachment protein beta) This gene encodes a member of the soluble N-ethyl-maleimide-sensitive fusion attachment protein (SNAP) family. SNAP proteins play a critical role in the docking and fusion of vesicles to target membranes as part of the 20S NSF-SNAP-SNARE complex. This gene encodes the SNAP beta isoform which has been shown to be preferentially expressed in brain tissue. The encoded protein also interacts with the GluR2 α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunit C-terminus and may play a role as a chaperone in the molecular processing of the AMPA receptor. [provided by RefSeq, Mar 2017]

NAPB Gene-Disease associations (from GenCC):

developmental and epileptic encephalopathy 107
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P

NAPB links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.14895123).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NAPB	NM_022080.3 link	c.230G>A	p.Ser77Asn	missense_variant	Exon 3 of 11	ENST00000377026.4	NP_071363.1	Q9H115-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NAPB	ENST00000377026.4 link	c.230G>A	p.Ser77Asn	missense_variant	Exon 3 of 11	1	NM_022080.3	ENSP00000366225.4		Q9H115-1

Frequencies

GnomAD3 genomes

AF:

0.0000854

AC:

AN:

152198

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000850

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000119

AC:

AN:

251104

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000869

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000479

AC:

AN:

1461388

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726986

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33472

American (AMR)

AF:

0.000157

AC:

AN:

44710

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39682

South Asian (SAS)

AF:

0.00

AC:

AN:

86230

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53412

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5752

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111622

Other (OTH)

AF:

0.00

AC:

AN:

60376

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.0000854

AC:

AN:

152198

Hom.:

Cov.:

AF XY:

0.000108

AC XY:

AN XY:

74356

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41450

American (AMR)

AF:

0.000850

AC:

AN:

15288

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5192

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10610

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68032

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.463

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000453

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Jun 07, 2025

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.230G>A (p.S77N) alteration is located in exon 3 (coding exon 3) of the NAPB gene. This alteration results from a G to A substitution at nucleotide position 230, causing the serine (S) at amino acid position 77 to be replaced by an asparagine (N). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.13

BayesDel_addAF

Benign

-0.34

BayesDel_noAF

Benign

-0.48

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.11

.;T

Eigen

Benign

0.031

Eigen_PC

Uncertain

0.25

FATHMM_MKL

Uncertain

0.91

LIST_S2

Uncertain

0.88

D;D

M_CAP

Benign

0.036

MetaRNN

Benign

0.15

T;T

MetaSVM

Benign

-0.66

MutationAssessor

Benign

0.48

.;N

PhyloP100

6.0

PrimateAI

Pathogenic

0.80

PROVEAN

Benign

-0.96

.;N

REVEL

Benign

0.27

Sift

Benign

0.20

.;T

Sift4G

Benign

0.35

T;T

Polyphen

0.0020

.;B

Vest4

0.077

MutPred

0.30

.;Gain of helix (P = 0.0425);

MVP

0.47

MPC

0.53

ClinPred

0.25

GERP RS

5.6

Varity_R

0.33

gMVP

0.21

Mutation Taster

=259/41

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over