6-31530878-CA-C

Variant names:

• chr6-31530878-CA-C
• NM_004640.7:c.1170delT

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PVS1_Moderate PM2

The NM_004640.7(DDX39B):​c.1170delT​(p.Phe390LeufsTer29) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: DDX39B NM_004640.7 frameshift
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.38

Genes affected

DDX39B (HGNC:13917): (DExD-box helicase 39B) This gene encodes a member of the DEAD box family of RNA-dependent ATPases that mediate ATP hydrolysis during pre-mRNA splicing. The encoded protein is an essential splicing factor required for association of U2 small nuclear ribonucleoprotein with pre-mRNA, and it also plays an important role in mRNA export from the nucleus to the cytoplasm. This gene belongs to a cluster of genes localized in the vicinity of the genes encoding tumor necrosis factor alpha and tumor necrosis factor beta. These genes are all within the human major histocompatibility complex class III region. Mutations in this gene may be associated with rheumatoid arthritis. Alternative splicing results in multiple transcript variants. Related pseudogenes have been identified on both chromosomes 6 and 11. Read-through transcription also occurs between this gene and the upstream ATP6V1G2 (ATPase, H+ transporting, lysosomal 13kDa, V1 subunit G2) gene. [provided by RefSeq, Feb 2011]

ATP6V1G2-DDX39B (HGNC:41999): (ATP6V1G2-DDX39B readthrough (NMD candidate)) This locus represents naturally occurring read-through transcription between the neighboring ATP6V1G2 (ATPase, H+ transporting, lysosomal 13kDa, V1 subunit G2) and DDX39B (DEAD box polypeptide 39B) genes located in the major histocompatibility complex class III region of chromosome 6. The read-through transcript and is a candidate for nonsense-mediated mRNA decay (NMD), and is thus unlikely to produce a protein product. [provided by RefSeq, Feb 2011]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0909 CDS is truncated, and there are 0 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DDX39B	NM_004640.7	c.1170delT	p.Phe390LeufsTer29	frameshift_variant	Exon 10 of 11	ENST00000396172.6	NP_004631.1
DDX39B	NM_080598.6	c.1170delT	p.Phe390LeufsTer29	frameshift_variant	Exon 10 of 11		NP_542165.1
DDX39B	NR_037852.2	n.1135delT		non_coding_transcript_exon_variant	Exon 8 of 9
ATP6V1G2-DDX39B	NR_037853.1	n.1973delT		non_coding_transcript_exon_variant	Exon 12 of 13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DDX39B	ENST00000396172.6	c.1170delT	p.Phe390LeufsTer29	frameshift_variant	Exon 10 of 11	1	NM_004640.7	ENSP00000379475.1
ATP6V1G2-DDX39B	ENST00000376185.5	n.*1384delT		non_coding_transcript_exon_variant	Exon 12 of 13	2		ENSP00000365356.1
ATP6V1G2-DDX39B	ENST00000376185.5	n.*1384delT		3_prime_UTR_variant	Exon 12 of 13	2		ENSP00000365356.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 35

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Feb 20, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); Frameshift variant predicted to result in protein truncation as the last 39 amino acids are replaced with 28 different amino acids, although loss-of-function variants have not been reported downstream of this position in the protein; Has not been previously published as pathogenic or benign to our knowledge; Variants in candidate genes are classified as variants of uncertain significance in accordance with ACMG guidelines (Richards et al., 2015) -

Computational scores

Source: dbNSFP v4.3

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr6-31498655;