Genetic Variant ST8SIA1:p.Gln330His (chr12-22201633-T-G) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_003034.4(ST8SIA1):c.990A>C(p.Gln330His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,772 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

ST8SIA1
NM_003034.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 0.461

Publications

0 publications found

Variant links:

Genes affected

ST8SIA1 (HGNC:10869): (ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 1) Gangliosides are membrane-bound glycosphingolipids containing sialic acid. Ganglioside GD3 is known to be important for cell adhesion and growth of cultured malignant cells. The protein encoded by this gene is a type II membrane protein that catalyzes the transfer of sialic acid from CMP-sialic acid to GM3 to produce gangliosides GD3 and GT3. The encoded protein may be found in the Golgi apparatus and is a member of glycosyltransferase family 29. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Jan 2015]

ST8SIA1 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ST8SIA1	NM_003034.4 link	c.990A>C	p.Gln330His	missense_variant	Exon 5 of 5	ENST00000396037.9	NP_003025.1	Q92185-1
ST8SIA1	NM_001304450.2 link	c.561A>C	p.Gln187His	missense_variant	Exon 4 of 4		NP_001291379.1	Q92185

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ST8SIA1	ENST00000396037.9 link	c.990A>C	p.Gln330His	missense_variant	Exon 5 of 5	1	NM_003034.4	ENSP00000379353.3		Q92185-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461772

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727192

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33462

American (AMR)

AF:

0.00

AC:

AN:

44710

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.00

AC:

AN:

86252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5756

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111954

Other (OTH)

AF:

0.00

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

not specified

Uncertain:1

May 14, 2025

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.990A>C (p.Q330H) alteration is located in exon 5 (coding exon 5) of the ST8SIA1 gene. This alteration results from a A to C substitution at nucleotide position 990, causing the glutamine (Q) at amino acid position 330 to be replaced by a histidine (H). 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

Pathogenic

0.73

BayesDel_addAF

Uncertain

0.12

BayesDel_noAF

Uncertain

-0.060

CADD

Benign

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.22

Eigen

Benign

-0.11

Eigen_PC

Benign

-0.16

FATHMM_MKL

Uncertain

0.91

LIST_S2

Uncertain

0.89

M_CAP

Benign

0.040

MetaRNN

Uncertain

0.57

MetaSVM

Benign

-0.81

MutationAssessor

Benign

1.8

PhyloP100

0.46

PrimateAI

Uncertain

0.76

PROVEAN

Uncertain

-2.4

REVEL

Uncertain

0.33

Sift

Benign

0.14

Sift4G

Benign

0.26

Polyphen

0.47

Vest4

0.74

MutPred

0.62

Loss of catalytic residue at Q330 (P = 0.0585);

MVP

0.52

MPC

1.2

ClinPred

0.91

GERP RS

-3.0

Varity_R

0.30

gMVP

0.92

Mutation Taster

=42/58

disease causing

(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