16-29664620-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_003123.6(SPN):c.892G>C(p.Gly298Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000694 in 1,441,888 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: 31)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: SPN NM_003123.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.94

Genes affected

SPN (HGNC:11249): (sialophorin) This gene encodes a highly sialylated glycoprotein that functions in antigen-specific activation of T cells, and is found on the surface of thymocytes, T lymphocytes, monocytes, granulocytes, and some B lymphocytes. It contains a mucin-like extracellular domain, a transmembrane region and a carboxy-terminal intracellular region. The extracellular domain has a high proportion of serine and threonine residues, allowing extensive O-glycosylation, and has one potential N-glycosylation site, while the carboxy-terminal region has potential phosphorylation sites that may mediate transduction of activation signals. Different glycoforms of this protein have been described. In stimulated immune cells, proteolytic cleavage of the extracellular domain occurs in some cell types, releasing a soluble extracellular fragment. Defects in expression of this gene are associated with Wiskott-Aldrich syndrome. [provided by RefSeq, Sep 2017]

QPRT (HGNC:9755): (quinolinate phosphoribosyltransferase) This gene encodes a key enzyme in catabolism of quinolinate, an intermediate in the tryptophan-nicotinamide adenine dinucleotide pathway. Quinolinate acts as a most potent endogenous exitotoxin to neurons. Elevation of quinolinate levels in the brain has been linked to the pathogenesis of neurodegenerative disorders such as epilepsy, Alzheimer's disease, and Huntington's disease. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2015]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.25694382).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SPN	NM_003123.6	c.892G>C	p.Gly298Arg	missense_variant	2/2	ENST00000652691.1
SPN	NM_001030288.4	c.892G>C	p.Gly298Arg	missense_variant	2/2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SPN	ENST00000652691.1	c.892G>C	p.Gly298Arg	missense_variant	2/2		NM_003123.6	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.94e-7 AC: 1 AN: 1441888 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 716032

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000239

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 11, 2022

The c.892G>C (p.G298R) alteration is located in exon 2 (coding exon 1) of the SPN gene. This alteration results from a G to C substitution at nucleotide position 892, causing the glycine (G) at amino acid position 298 to be replaced by an arginine (R). 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	0.30
BayesDel_addAF	Benign	-0.13	T
BayesDel_noAF	Benign	-0.42
Cadd	Uncertain	24
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.71	D;.;D
Eigen	Benign	0.083
Eigen_PC	Benign	-0.034
FATHMM_MKL	Benign	0.37	N
M_CAP	Benign	0.012	T
MetaRNN	Benign	0.26	T;T;T
MetaSVM	Benign	-0.94	T
MutationAssessor	Benign	1.6	L;.;L
MutationTaster	Benign	1.0	N;N
PrimateAI	Uncertain	0.54	T
PROVEAN	Uncertain	-3.6	D;D;D
REVEL	Benign	0.13
Sift	Benign	0.16	T;T;T
Sift4G	Benign	0.10	T;T;T
Polyphen		1.0	D;.;D
Vest4		0.20
MutPred		0.51		Gain of MoRF binding (P = 0.0224);Gain of MoRF binding (P = 0.0224);Gain of MoRF binding (P = 0.0224);
MVP		0.56
MPC		0.78
ClinPred		0.97	D
GERP RS		4.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.21

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs779504783; hg19: chr16-29675941;