5-81252771-C-T

Variant names:

• chr5-81252771-C-T
• rs140687986
• NM_001099735.2:c.229C>T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001099735.2(CKMT2):​c.229C>T​(p.Arg77Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000013 in 1,614,228 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R77H) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000012 (0 hom.)
• Consequence: CKMT2 NM_001099735.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.773

Genes affected

CKMT2 (HGNC:1996): (creatine kinase, mitochondrial 2) Mitochondrial creatine kinase (MtCK) is responsible for the transfer of high energy phosphate from mitochondria to the cytosolic carrier, creatine. It belongs to the creatine kinase isoenzyme family. It exists as two isoenzymes, sarcomeric MtCK and ubiquitous MtCK, encoded by separate genes. Mitochondrial creatine kinase occurs in two different oligomeric forms: dimers and octamers, in contrast to the exclusively dimeric cytosolic creatine kinase isoenzymes. Sarcomeric mitochondrial creatine kinase has 80% homology with the coding exons of ubiquitous mitochondrial creatine kinase. This gene contains sequences homologous to several motifs that are shared among some nuclear genes encoding mitochondrial proteins and thus may be essential for the coordinated activation of these genes during mitochondrial biogenesis. Three transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Jul 2008]

CKMT2-AS1 (HGNC:48997): (CKMT2 antisense RNA 1)

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.14393473).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CKMT2	NM_001099735.2	c.229C>T	p.Arg77Cys	missense_variant	Exon 3 of 10	ENST00000254035.9	NP_001093205.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CKMT2	ENST00000254035.9	c.229C>T	p.Arg77Cys	missense_variant	Exon 3 of 10	1	NM_001099735.2	ENSP00000254035.4

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152218 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000482

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

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: 0.00

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251450 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135904

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000123 AC: 18 AN: 1461892 Hom.: 0 Cov.: 32 AF XY: 0.0000124 AC XY: 9 AN XY: 727248

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000504

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.0000187

Gnomad4 NFE exome AF: 0.00000899

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152336 Hom.: 0 Cov.: 32 AF XY: 0.0000268 AC XY: 2 AN XY: 74496

Gnomad4 AFR AF: 0.0000481

Gnomad4 AMR AF: 0.0000653

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000113

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.000259 AC: 1

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Jun 18, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.229C>T (p.R77C) alteration is located in exon 4 (coding exon 2) of the CKMT2 gene. This alteration results from a C to T substitution at nucleotide position 229, causing the arginine (R) at amino acid position 77 to be replaced by a cysteine (C). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.089
BayesDel_addAF	Benign	-0.17	T
BayesDel_noAF	Benign	-0.31
CADD	Benign	22
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.44	T;.;T;T;T
Eigen	Benign	-0.45
Eigen_PC	Benign	-0.33
FATHMM_MKL	Benign	0.48	N
LIST_S2	Uncertain	0.91	.;D;D;.;D
M_CAP	Benign	0.037	D
MetaRNN	Benign	0.14	T;T;T;T;T
MetaSVM	Benign	-0.95	T
MutationAssessor	Benign	1.1	L;.;L;L;.
PrimateAI	Uncertain	0.57	T
PROVEAN	Benign	-1.0	N;N;N;N;N
REVEL	Benign	0.16
Sift	Benign	0.30	T;T;T;T;T
Sift4G	Benign	0.27	T;T;T;T;T
Polyphen		0.080	B;.;B;B;.
Vest4		0.35
MVP		0.72
MPC		0.50
ClinPred		0.11	T
GERP RS		3.3
Varity_R		0.47
gMVP		0.78

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

LitVar

Other links and lift over

dbSNP: rs140687986; hg19: chr5-80548590;