rs1555789463

Positions:

• chr20-18535747-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP5_Moderate

The NM_006363.6(SEC23B):​c.1404+5G>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000138 in 1,453,574 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SEC23B NM_006363.6 splice_region, intron
• Scores: Splicing: ADA: 0.9965
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 2.06

Genes affected

SEC23B (HGNC:10702): (SEC23 homolog B, COPII coat complex component) The protein encoded by this gene is a member of the SEC23 subfamily of the SEC23/SEC24 family, which is involved in vesicle trafficking. The encoded protein has similarity to yeast Sec23p component of COPII. COPII is the coat protein complex responsible for vesicle budding from the ER. The function of this gene product has been implicated in cargo selection and concentration. Multiple alternatively spliced transcript variants have been identified in this gene. [provided by RefSeq, Feb 2010]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 20-18535747-G-A is Pathogenic according to our data. Variant chr20-18535747-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 532195.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SEC23B	NM_006363.6	c.1404+5G>A		splice_region_variant, intron_variant		ENST00000650089.1	NP_006354.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SEC23B	ENST00000650089.1	c.1404+5G>A		splice_region_variant, intron_variant			NM_006363.6	ENSP00000497473.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000138 AC: 2 AN: 1453574 Hom.: 0 Cov.: 28 AF XY: 0.00000276 AC XY: 2 AN XY: 723748

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.00000181

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Congenital dyserythropoietic anemia, type II;C4225179:Cowden syndrome 7 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 13, 2018

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Experimental studies have shown that this change leads to the in-frame deletion of exon 12 that results in an unstable transcript (PMID: 23453696). This variant has been observed on the opposite chromosome (in trans) from a pathogenic variant in an individual affected with dyserythropoietic anemia (PMID:23453696). This finding is consistent with autosomal recessive inheritance, and suggests that this variant contributes to disease. This variant is not present in population databases (ExAC no frequency). This sequence change falls in intron 12 of the SEC23B gene. It does not directly change the encoded amino acid sequence of the SEC23B protein, but it affects a nucleotide within the consensus splice site of the intron. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.44
CADD	Benign	14
DANN	Benign	0.72
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.86
SpliceAI score (max)		0.37		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.37		Position offset: -5

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555789463; hg19: chr20-18516391;