20-17969908-A-T

Variant names:

• chr20-17969908-A-T
• rs761854428
• NM_052865.4:c.49A>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_Strong PM2

The NM_052865.4(MGME1):​c.49A>T​(p.Lys17*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,438 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MGME1 NM_052865.4 stop_gained
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 2.35
• Publications: 0 publications found

Genes affected

MGME1 (HGNC:16205): (mitochondrial genome maintenance exonuclease 1) The protein encoded by this gene is a nuclear-encoded mitochondrial protein necessary for the maintenance of mitochondrial genome synthesis. The encoded protein is a RecB-type exonuclease and primarily cleaves single-stranded DNA. Defects in this gene have been associated with mitochondrial DNA depletion syndrome-11. Three transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2015]

OVOL2 (HGNC:15804): (ovo like zinc finger 2) This gene encodes a member of the evolutionarily conserved ovo-like protein family. Mammalian members of this family contain a single zinc finger domain composed of a tetrad of C2H2 zinc fingers with variable N- and C-terminal extensions that contain intrinsically disordered domains. Members of this family are involved in epithelial development and differentiation. Knockout of this gene in mouse results in early embryonic lethality with phenotypes that include neurectoderm expansion, impaired vascularization, and heart anomalies. In humans, allelic variants of this gene have been associated with posterior polymorphous corneal dystrophy. [provided by RefSeq, Apr 2016]

OVOL2 Gene-Disease associations (from GenCC):

• posterior polymorphous corneal dystrophy 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, LIMITED Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• congenital hereditary endothelial dystrophy type I

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• posterior polymorphous corneal dystrophy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 11 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_052865.4. 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
	MGME1	NM_052865.4	MANE Select	c.49A>T	p.Lys17*	stop_gained	Exon 2 of 5	NP_443097.1	Q9BQP7
	MGME1	NM_001310338.2		c.49A>T	p.Lys17*	stop_gained	Exon 2 of 6	NP_001297267.1
	MGME1	NM_001363738.2		c.49A>T	p.Lys17*	stop_gained	Exon 2 of 5	NP_001350667.1	Q5QPE8

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MGME1	ENST00000377710.10	TSL:1 MANE Select	c.49A>T	p.Lys17*	stop_gained	Exon 2 of 5	ENSP00000366939.5	Q9BQP7
	MGME1	ENST00000948803.1		c.49A>T	p.Lys17*	stop_gained	Exon 1 of 5	ENSP00000618862.1
	MGME1	ENST00000895985.1		c.49A>T	p.Lys17*	stop_gained	Exon 1 of 5	ENSP00000566044.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461438 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727046

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

African (AFR) AF: 0.00 AC: 0 AN: 33416

American (AMR) AF: 0.00 AC: 0 AN: 44564

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26126

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86192

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5756

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111898

Other (OTH) AF: 0.00 AC: 0 AN: 60370

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.27
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Benign	0.12
Eigen_PC	Benign	-0.17
FATHMM_MKL	Benign	0.20	N
PhyloP100		2.3
Vest4		0.071
GERP RS		3.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Mutation Taster		=13/187	disease causing (fs/PTC)

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

Other links and lift over

dbSNP: rs761854428; hg19: chr20-17950551;