chr6-70856970-T-A

Variant names:

• chr6-70856970-T-A
• rs1771451558
• NM_001044305.3:c.901T>A

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_001044305.3(SMAP1):​c.901T>A​(p.Ser301Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000248 in 1,613,886 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: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: SMAP1 NM_001044305.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.28
• Publications: 0 publications found

Genes affected

SMAP1 (HGNC:19651): (small ArfGAP 1) The protein encoded by this gene is similar to the mouse stromal membrane-associated protein-1. This similarity suggests that this human gene product is also a type II membrane glycoprotein involved in the erythropoietic stimulatory activity of stromal cells. Alternate splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, Jul 2008]

B3GAT2 (HGNC:922): (beta-1,3-glucuronyltransferase 2) The product of this gene is a transmembrane protein belonging to the glucuronyltransferase family, and catalyzes the transfer of a beta-1,3 linked glucuronic acid to a terminal galactose in different glycoproteins or glycolipids containing a Gal-beta-1-4GlcNAc or Gal-beta-1-3GlcNAc residue. The encoded protein is involved in the synthesis of the human natural killer-1 (HNK-1) carbohydrate epitope, a sulfated trisaccharide implicated in cellular migration and adhesion in the nervous system. [provided by RefSeq, Jul 2008]

ACMG classification

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.38800496).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMAP1	NM_001044305.3	c.901T>A	p.Ser301Thr	missense_variant	Exon 9 of 11	ENST00000370455.8	NP_001037770.1
B3GAT2	NM_080742.3	c.*4693A>T		3_prime_UTR_variant	Exon 4 of 4	ENST00000230053.11	NP_542780.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMAP1	ENST00000370455.8	c.901T>A	p.Ser301Thr	missense_variant	Exon 9 of 11	1	NM_001044305.3	ENSP00000359484.3
B3GAT2	ENST00000230053.11	c.*4693A>T		3_prime_UTR_variant	Exon 4 of 4	1	NM_080742.3	ENSP00000230053.6

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152220 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461666 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727106

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

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26126

East Asian (EAS) AF: 0.00 AC: 0 AN: 39672

South Asian (SAS) AF: 0.00 AC: 0 AN: 86238

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

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

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111862

Other (OTH) AF: 0.00 AC: 0 AN: 60390

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152220 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74370

African (AFR) AF: 0.00 AC: 0 AN: 41454

American (AMR) AF: 0.00 AC: 0 AN: 15278

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5202

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68040

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.0000312 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Mar 22, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.901T>A (p.S301T) alteration is located in exon 9 (coding exon 9) of the SMAP1 gene. This alteration results from a T to A substitution at nucleotide position 901, causing the serine (S) at amino acid position 301 to be replaced by a threonine (T). 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	0.17
BayesDel_addAF	Benign	-0.049	T
BayesDel_noAF	Benign	-0.31
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Benign	0.040	.;.;T;.
Eigen	Uncertain	0.59
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D;D;D
M_CAP	Benign	0.047	D
MetaRNN	Benign	0.39	T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.5	.;.;M;.
PhyloP100		7.3
PrimateAI	Uncertain	0.70	T
PROVEAN	Benign	-1.1	N;N;N;.
REVEL	Benign	0.18
Sift	Benign	0.21	T;T;T;.
Sift4G	Benign	0.29	T;T;T;T
Polyphen		1.0	D;D;P;.
Vest4		0.55
MVP		0.47
MPC		0.35
ClinPred		0.94	D
GERP RS		5.6
Varity_R		0.24
gMVP		0.77
Mutation Taster		=53/47	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: rs1771451558; hg19: chr6-71566673;