Genetic Variant DDX20:p.Ala2Glu (chr1-111755929-C-A) – ACMG Classification: Uncertain_significance (2 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_007204.5(DDX20):c.5C>A(p.Ala2Glu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000705 in 1,418,596 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A2G) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 7.0e-7 ( 0 hom. )

Consequence

DDX20
NM_007204.5 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 1.43

Publications

0 publications found

Variant links:

Genes affected

DDX20 (HGNC:2743): (DEAD-box helicase 20) DEAD box proteins, characterized by the conserved motif Asp-Glu-Ala-Asp (DEAD), are putative RNA helicases. They are implicated in a number of cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly. Based on their distribution patterns, some members of this family are believed to be involved in embryogenesis, spermatogenesis, and cellular growth and division. This gene encodes a DEAD box protein, which has an ATPase activity and is a component of the survival of motor neurons (SMN) complex. This protein interacts directly with SMN, the spinal muscular atrophy gene product, and may play a catalytic role in the function of the SMN complex on RNPs. [provided by RefSeq, Jul 2008]

DDX20 links:

INKA2 (HGNC:28045): (inka box actin regulator 2) Enables protein kinase binding activity. Predicted to be involved in negative regulation of catalytic activity. Located in nucleoplasm. [provided by Alliance of Genome Resources, Apr 2022]

INKA2 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DDX20	NM_007204.5 link	c.5C>A	p.Ala2Glu	missense_variant	Exon 1 of 11	ENST00000369702.5	NP_009135.4	Q9UHI6-1Q9H4N4
INKA2	NM_198926.2 link	c.-217G>T		upstream_gene_variant			NP_945120.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DDX20	ENST00000369702.5 link	c.5C>A	p.Ala2Glu	missense_variant	Exon 1 of 11	1	NM_007204.5	ENSP00000358716.4		Q9UHI6-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

7.05e-7

AC:

AN:

1418596

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

699988

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

32222

American (AMR)

AF:

0.00

AC:

AN:

40478

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

23604

East Asian (EAS)

AF:

0.00

AC:

AN:

38932

South Asian (SAS)

AF:

0.00

AC:

AN:

81714

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51810

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5562

European-Non Finnish (NFE)

AF:

9.21e-7

AC:

AN:

1086042

Other (OTH)

AF:

0.00

AC:

AN:

58232

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.275

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.25

BayesDel_addAF

Uncertain

0.066

BayesDel_noAF

Benign

-0.14

CADD

Uncertain

(source)

DANN

Benign

0.97

DEOGEN2

Benign

0.17

Eigen

Uncertain

0.52

Eigen_PC

Uncertain

0.45

FATHMM_MKL

Benign

0.49

LIST_S2

Benign

0.42

M_CAP

Pathogenic

0.33

MetaRNN

Uncertain

0.66

MetaSVM

Benign

-1.0

MutationAssessor

Uncertain

2.1

PhyloP100

1.4

PrimateAI

Uncertain

0.79

PROVEAN

Benign

-0.50

REVEL

Benign

0.20

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Polyphen

1.0

Vest4

0.41

MutPred

0.24

Loss of catalytic residue at A2 (P = 0.2429);

MVP

0.76

MPC

0.092

ClinPred

0.95

GERP RS

4.9

PromoterAI

-0.54

Under-expression

(source)

Varity_R

0.55

gMVP

0.69

Mutation Taster

=78/22

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

Other links and lift over