16-29664354-C-T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_003123.6(SPN):c.626C>T(p.Thr209Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000378 in 1,613,570 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.00024 (0 hom., cov: 31)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: SPN NM_003123.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.144

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 Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.03276363).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SPN	NM_003123.6	c.626C>T	p.Thr209Ile	missense_variant	2/2	ENST00000652691.1
SPN	NM_001030288.4	c.626C>T	p.Thr209Ile	missense_variant	2/2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SPN	ENST00000652691.1	c.626C>T	p.Thr209Ile	missense_variant	2/2		NM_003123.6	P1

Frequencies

GnomAD3 genomes AF: 0.000230 AC: 35 AN: 152050 Hom.: 0 Cov.: 31

Gnomad AFR AF: 0.000821

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

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

GnomAD3 exomes AF: 0.0000677 AC: 17 AN: 251276 Hom.: 0 AF XY: 0.0000515 AC XY: 7 AN XY: 135838

Gnomad AFR exome AF: 0.000986

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS 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: 0.0000164 AC: 24 AN: 1461402 Hom.: 0 Cov.: 31 AF XY: 0.0000165 AC XY: 12 AN XY: 727042

Gnomad4 AFR exome AF: 0.000687

Gnomad4 AMR exome AF: 0.0000224

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 AF: 0.000243 AC: 37 AN: 152168 Hom.: 0 Cov.: 31 AF XY: 0.000242 AC XY: 18 AN XY: 74404

Gnomad4 AFR AF: 0.000866

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.000197 Hom.: 0

Bravo AF: 0.000212

ESP6500AA AF: 0.000455 AC: 2

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.0000577 AC: 7

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

Dec 07, 2021

The c.626C>T (p.T209I) alteration is located in exon 2 (coding exon 1) of the SPN gene. This alteration results from a C to T substitution at nucleotide position 626, causing the threonine (T) at amino acid position 209 to be replaced by an isoleucine (I). 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	0.22
BayesDel_addAF	Benign	-0.42	T
BayesDel_noAF	Benign	-0.43
Cadd	Benign	14
Dann	Benign	0.90
DEOGEN2	Uncertain	0.47	T;.;T
Eigen	Benign	-0.66
Eigen_PC	Benign	-0.74
FATHMM_MKL	Benign	0.062	N
M_CAP	Benign	0.024	T
MetaRNN	Benign	0.033	T;T;T
MetaSVM	Benign	-0.75	T
MutationAssessor	Benign	1.2	L;.;L
MutationTaster	Benign	1.0	N;N
PrimateAI	Benign	0.25	T
PROVEAN	Benign	-2.2	N;N;N
REVEL	Benign	0.089
Sift	Benign	0.22	T;T;T
Sift4G	Benign	0.093	T;T;T
Polyphen		0.30	B;.;B
Vest4		0.14
MVP		0.83
MPC		0.20
ClinPred		0.018	T
GERP RS		1.9
Varity_R		0.046

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: rs141727997; hg19: chr16-29675675;