NM_006441.4:c.378A>C

Variant names:

• chr15-79889094-T-G
• rs138155613
• NM_006441.4:c.378A>C

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_006441.4(MTHFS):​c.378A>C​(p.Thr126Thr) variant causes a splice region, synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,822 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. T126T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MTHFS NM_006441.4 splice_region, synonymous
• Scores: Splicing: ADA: 0.04294
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.120
• Publications: 0 publications found

Genes affected

MTHFS (HGNC:7437): (methenyltetrahydrofolate synthetase) The protein encoded by this gene is an enzyme that catalyzes the conversion of 5-formyltetrahydrofolate to 5,10-methenyltetrahydrofolate, a precursor of reduced folates involved in 1-carbon metabolism. An increased activity of the encoded protein can result in an increased folate turnover rate and folate depletion. Three transcript variants encoding two different isoforms have been found for this gene. [provided by RefSeq, Jun 2011]

ST20-MTHFS (HGNC:44655): (ST20-MTHFS readthrough) This locus represents naturally occurring read-through transcription between the neighboring suppressor of tumorigenicity 20 and 5,10-methenyltetrahydrofolate synthetase (5-formyltetrahydrofolate cyclo-ligase) genes on chromosome 15. The read-through transcript produces a fusion protein that shares sequence identity with each individual gene product. [provided by RefSeq, Dec 2010]

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.69).
• BP7: Synonymous conserved (PhyloP=0.12 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_006441.4. 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
	MTHFS	NM_006441.4	MANE Select	c.378A>C	p.Thr126Thr	splice_region synonymous	Exon 2 of 3	NP_006432.1	P49914-1
	ST20-MTHFS	NM_001199760.2		c.306A>C	p.Thr102Thr	splice_region synonymous	Exon 3 of 4	NP_001186689.1	A0A0A6YYL1
	MTHFS	NM_001199758.1		c.207A>C	p.Thr69Thr	splice_region synonymous	Exon 2 of 3	NP_001186687.1	P49914

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MTHFS	ENST00000258874.4	TSL:1 MANE Select	c.378A>C	p.Thr126Thr	splice_region synonymous	Exon 2 of 3	ENSP00000258874.4	P49914-1
	ST20-MTHFS	ENST00000479961.1	TSL:3	c.306A>C	p.Thr102Thr	splice_region synonymous	Exon 3 of 4	ENSP00000455643.1
	MTHFS	ENST00000559722.2	TSL:2	c.465A>C	p.Thr155Thr	splice_region synonymous	Exon 2 of 3	ENSP00000489076.1	A0A0U1RQM3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461822 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727208

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111966

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.69
CADD	Benign	10
DANN	Benign	0.76
PhyloP100		0.12

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.043
dbscSNV1_RF	Benign	0.46
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

Other links and lift over

dbSNP: rs138155613; hg19: chr15-80181436;