20-58652106-T-TC

Variant names:

• chr20-58652106-T-TC
• rs1461082513
• NM_001001433.3:c.102dupC

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_001001433.3(STX16):​c.102dupC​(p.Ser35GlnfsTer7) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,204 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: STX16 NM_001001433.3 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.74

Genes affected

STX16 (HGNC:11431): (syntaxin 16) This gene encodes a protein that is a member of the syntaxin or t-SNARE (target-SNAP receptor) family. These proteins are found on cell membranes and serve as the targets for V-SNARES (vesicle-SNAP receptors) permitting specific synaptic vesicle docking and fusion. A microdeletion in the region of chromosome 20 where this gene is located has been associated with pseudohypoparathyroidism type Ib. Multiple transcript variants have been found for this gene. Read-through transcription also exists between this gene and the neighboring downstream aminopeptidase-like 1 (NPEPL1) gene. [provided by RefSeq, Mar 2011]

STX16-NPEPL1 (HGNC:41993): (STX16-NPEPL1 readthrough (NMD candidate)) This locus represents naturally occurring read-through transcription between the neighboring syntaxin 16 (STX16) and aminopeptidase-like 1 (NPEPL1) genes on chromosome 20. The read-through transcript is a candidate for nonsense-mediated mRNA decay (NMD), and is thus unlikely to produce a protein product. [provided by RefSeq, Mar 2011]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
STX16	NM_001001433.3	c.102dupC	p.Ser35GlnfsTer7	frameshift_variant	Exon 1 of 9	ENST00000371141.8	NP_001001433.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
STX16	ENST00000371141.8	c.102dupC	p.Ser35GlnfsTer7	frameshift_variant	Exon 1 of 9	2	NM_001001433.3	ENSP00000360183.4
STX16-NPEPL1	ENST00000530122.1	n.102dupC		non_coding_transcript_exon_variant	Exon 1 of 23	5		ENSP00000457522.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152204 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

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: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152204 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74356

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

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

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Jul 22, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. This variant has not been reported in the literature in individuals affected with STX16-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Ser35Glnfs*7) in the STX16 gene. It is expected to result in an absent or disrupted protein product. However, the current clinical and genetic evidence is not sufficient to establish whether loss-of-function variants in STX16 cause disease. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.21		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.21		Position offset: 32

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1461082513; hg19: chr20-57227162;