chr20-427443-A-G

Variant names:

• chr20-427443-A-G
• rs566912235
• NM_031229.4:c.1160A>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP3 PP5_Moderate

The NM_031229.4(RBCK1):​c.1160A>G​(p.Asn387Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,202 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: RBCK1 NM_031229.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 8.55
• Publications: 6 publications found

Genes affected

RBCK1 (HGNC:15864): (RANBP2-type and C3HC4-type zinc finger containing 1) Enables several functions, including identical protein binding activity; protein sequestering activity; and ubiquitin binding activity. Involved in several processes, including T cell receptor signaling pathway; cellular protein metabolic process; and regulation of DNA-binding transcription factor activity. Part of LUBAC complex. Implicated in glycogen storage disease. [provided by Alliance of Genome Resources, Apr 2022]

TBC1D20 (HGNC:16133): (TBC1 domain family member 20) This gene encodes a protein that belongs to a family of GTPase activator proteins of Rab-like small GTPases. The encoded protein and its cognate GTPase, Rab1, bind the nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) to mediate viral replication. Depletion of this protein inhibits replication of the virus and HCV infection. Mutations in this gene are associated with Warburg micro syndrome 4. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2014]

TBC1D20 Gene-Disease associations (from GenCC):

• Warburg micro syndrome 4

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P, PanelApp Australia
• Warburg micro syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 20-427443-A-G is Pathogenic according to our data. Variant chr20-427443-A-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 140626.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_031229.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RBCK1	NM_031229.4	MANE Select	c.1160A>G	p.Asn387Ser	missense	Exon 9 of 12	NP_112506.2	Q9BYM8-1
	RBCK1	NM_001410770.1		c.1211A>G	p.Asn404Ser	missense	Exon 9 of 12	NP_001397699.1	A0A8V8TMZ2
	RBCK1	NM_006462.6		c.1034A>G	p.Asn345Ser	missense	Exon 8 of 11	NP_006453.1	Q9BYM8-3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	RBCK1	ENST00000356286.10	TSL:1 MANE Select	c.1160A>G	p.Asn387Ser	missense	Exon 9 of 12	ENSP00000348632.6	Q9BYM8-1
	RBCK1	ENST00000353660.7	TSL:1	c.1034A>G	p.Asn345Ser	missense	Exon 8 of 11	ENSP00000254960.5	Q9BYM8-3
	RBCK1	ENST00000382181.2	TSL:1	n.*180A>G		non_coding_transcript_exon	Exon 7 of 10	ENSP00000371616.3	Q9BYM8-4

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152202 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

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: 0.000478

GnomAD4 exome Cov.: 31

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152202 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74358

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

African (AFR) AF: 0.00 AC: 0 AN: 41452

American (AMR) AF: 0.00 AC: 0 AN: 15282

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3464

East Asian (EAS) AF: 0.00 AC: 0 AN: 5194

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68032

Other (OTH) AF: 0.000478 AC: 1 AN: 2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
1	-	-	Polyglucosan body myopathy 1 without immunodeficiency (1)
1	-	-	Polyglucosan body myopathy type 1 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.18
BayesDel_addAF	Benign	-0.090	T
BayesDel_noAF	Benign	-0.37
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.72	D
Eigen	Uncertain	0.67
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.97	D
M_CAP	Uncertain	0.094	D
MetaRNN	Uncertain	0.60	D
MetaSVM	Uncertain	-0.26	T
MutationAssessor	Benign	1.8	L
PhyloP100		8.6
PrimateAI	Uncertain	0.66	T
PROVEAN	Pathogenic	-4.7	D
REVEL	Pathogenic	0.75
Sift	Uncertain	0.0070	D
Sift4G	Uncertain	0.043	D
Polyphen		0.90	P
Vest4		0.55
MutPred		0.43		Gain of glycosylation at N387 (P = 0.1718)
MVP		0.78
MPC		0.95
ClinPred		0.99	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.54
gMVP		0.75
Mutation Taster		=6/94	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.60		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.60		Position offset: -1
DS_DL_spliceai		0.42		Position offset: 49

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

Other links and lift over

dbSNP: rs566912235; hg19: chr20-408087;