rs1554887222

Positions:

• chr10-100989791-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The NM_021830.5(TWNK):​c.1391T>C​(p.Leu464Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,890 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TWNK NM_021830.5 missense
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 7.99

Genes affected

TWNK (HGNC:1160): (twinkle mtDNA helicase) This gene encodes a hexameric DNA helicase which unwinds short stretches of double-stranded DNA in the 5' to 3' direction and, along with mitochondrial single-stranded DNA binding protein and mtDNA polymerase gamma, is thought to play a key role in mtDNA replication. The protein localizes to the mitochondrial matrix and mitochondrial nucleoids. Mutations in this gene cause infantile onset spinocerebellar ataxia (IOSCA) and progressive external ophthalmoplegia (PEO) and are also associated with several mitochondrial depletion syndromes. Alternative splicing results in multiple transcript variants encoding distinct isoforms.[provided by RefSeq, Aug 2009]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_021830.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.944
• PP5: Variant 10-100989791-T-C is Pathogenic according to our data. Variant chr10-100989791-T-C is described in ClinVar as [Pathogenic]. Clinvar id is 426105.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TWNK	NM_021830.5	c.1391T>C	p.Leu464Pro	missense_variant	2/5	ENST00000311916.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TWNK	ENST00000311916.8	c.1391T>C	p.Leu464Pro	missense_variant	2/5	1	NM_021830.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461890 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727248

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

Mitochondrial disease Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Wellcome Centre for Mitochondrial Research, Newcastle University

Apr 07, 2017

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.74
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.45
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.83	.;D;.;.;.
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Benign	0.85	T;T;T;T;T
M_CAP	Pathogenic	0.51	D
MetaRNN	Pathogenic	0.94	D;D;D;D;D
MetaSVM	Uncertain	0.66	D
MutationAssessor	Uncertain	2.2	.;M;M;.;.
MutationTaster	Benign	1.0	D;D
PROVEAN	Pathogenic	-5.4	.;D;D;.;.
REVEL	Pathogenic	0.88
Sift	Benign	0.036	.;D;D;.;.
Sift4G	Uncertain	0.031	.;D;D;.;.
Polyphen		0.85, 0.41	.;P;B;.;.
Vest4		0.97, 0.97
MutPred		0.80		.;Gain of disorder (P = 0.014);Gain of disorder (P = 0.014);.;.;
MVP		0.99
MPC		0.96
ClinPred		0.96	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.91
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554887222; hg19: chr10-102749548;