Genetic Variant NM_005896.4:c.395G>A (chr2-208248388-C-T) – ACMG Classification: Pathogenic (18 pts)

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PS3PM5PP3_StrongPP5_Very_Strong

The NM_005896.4(IDH1):c.395G>A(p.Arg132His) variant causes a missense change. The variant allele was found at a frequency of 0.00000992 in 1,613,530 control chromosomes in the GnomAD database, with no homozygous occurrence. There is a variant allele frequency bias in the population database for this variant (GnomAdExome4), which may indicate mosaicism or somatic mutations in the reference population data. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000996209: The p.Arg132H variant results in loss of its native enzymatic activity and gain of alternative enzymatic activity (producing D-2-hydroxyglutarate) (PMID 21446021). Structural studies demonstrated that when p.Arg132 is mutated to histidine (R132H), residues in the active site are shifted to produce structural changes consistent with reduced oxidative decarboxylation of isocitrate and acquisition of the ability to convert alpha-ketoglutarate to 2HG (PMID 19935646)." and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R132G) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000096 ( 0 hom. )

Consequence

IDH1
NM_005896.4 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:10O:4

Conservation

PhyloP100: 6.17

Publications

3887 publications found

Variant links:

Genes affected

IDH1 (HGNC:5382): (isocitrate dehydrogenase (NADP(+)) 1) Isocitrate dehydrogenases catalyze the oxidative decarboxylation of isocitrate to 2-oxoglutarate. These enzymes belong to two distinct subclasses, one of which utilizes NAD(+) as the electron acceptor and the other NADP(+). Five isocitrate dehydrogenases have been reported: three NAD(+)-dependent isocitrate dehydrogenases, which localize to the mitochondrial matrix, and two NADP(+)-dependent isocitrate dehydrogenases, one of which is mitochondrial and the other predominantly cytosolic. Each NADP(+)-dependent isozyme is a homodimer. The protein encoded by this gene is the NADP(+)-dependent isocitrate dehydrogenase found in the cytoplasm and peroxisomes. It contains the PTS-1 peroxisomal targeting signal sequence. The presence of this enzyme in peroxisomes suggests roles in the regeneration of NADPH for intraperoxisomal reductions, such as the conversion of 2, 4-dienoyl-CoAs to 3-enoyl-CoAs, as well as in peroxisomal reactions that consume 2-oxoglutarate, namely the alpha-hydroxylation of phytanic acid. The cytoplasmic enzyme serves a significant role in cytoplasmic NADPH production. Alternatively spliced transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Sep 2013]

IDH1 Gene-Disease associations (from GenCC):

Maffucci syndrome
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

IDH1 links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 18 ACMG points.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000996209: The p.Arg132H variant results in loss of its native enzymatic activity and gain of alternative enzymatic activity (producing D-2-hydroxyglutarate) (PMID 21446021). Structural studies demonstrated that when p.Arg132 is mutated to histidine (R132H), residues in the active site are shifted to produce structural changes consistent with reduced oxidative decarboxylation of isocitrate and acquisition of the ability to convert alpha-ketoglutarate to 2HG (PMID 19935646).; SCV005685410: "In support of this prediction, functional studies using cell lines show that this variant alters the enzymatic properties of IDH1 and results in a gain-of-function for NADPH-dependent reduction of alpha-ketoglutarate." PMID:19935646

PM5

Other missense variant is known to change same aminoacid residue: Variant chr2-208248389-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 375891.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.979

PP5

Variant 2-208248388-C-T is Pathogenic according to our data. Variant chr2-208248388-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 156444.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005896.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
IDH1	NM_005896.4	MANE Select	c.395G>A	p.Arg132His	missense	Exon 4 of 10	NP_005887.2
IDH1	NM_001282386.1		c.395G>A	p.Arg132His	missense	Exon 4 of 10	NP_001269315.1	O75874
IDH1	NM_001282387.1		c.395G>A	p.Arg132His	missense	Exon 4 of 10	NP_001269316.1	A0A024R3Y6

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
IDH1	ENST00000345146.7	TSL:1 MANE Select	c.395G>A	p.Arg132His	missense	Exon 4 of 10	ENSP00000260985.2	O75874
IDH1	ENST00000415913.5	TSL:1	c.395G>A	p.Arg132His	missense	Exon 4 of 10	ENSP00000390265.1	O75874
IDH1	ENST00000446179.5	TSL:1	c.395G>A	p.Arg132His	missense	Exon 4 of 10	ENSP00000410513.1	O75874

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

151806

Hom.:

Cov.:

show subpopulations

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:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00

AC:

AN:

251268

AF XY:

0.00

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000958

AC:

AN:

1461724

Hom.:

Cov.:

AF XY:

0.0000138

AC XY:

AN XY:

727172

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

33472

American (AMR)

AF:

0.0000224

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.0000383

AC:

AN:

26136

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.0000374

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00000720

AC:

AN:

1111882

Other (OTH)

AF:

0.00

AC:

AN:

60378

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000000000000111022), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.321

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000132

AC:

AN:

151806

Hom.:

Cov.:

AF XY:

0.0000270

AC XY:

AN XY:

74100

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

41346

American (AMR)

AF:

0.00

AC:

AN:

15256

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5186

South Asian (SAS)

AF:

0.00

AC:

AN:

4818

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10442

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

67980

Other (OTH)

AF:

0.00

AC:

AN:

2082

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.00233887), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.350

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

ExAC

AF:

0.0000165

AC:

ClinVar

ClinVar submissions

Significance:Pathogenic/Likely pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

not provided (3)

Enchondromatosis (2)

Glioma susceptibility 1 (2)

Glioblastoma multiforme, somatic (1)

Metaphyseal chondromatosis (1)

Metaphyseal chondromatosis with D-2-hydroxyglutaric aciduria (1)

Acute myeloid leukemia with NPM1 somatic mutations (1)

Astrocytoma IDH-mutant (1)

Neoplasm (1)

Oligodendroglioma (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.99

BayesDel_addAF

Pathogenic

0.30

BayesDel_noAF

Pathogenic

0.19

CADD

Benign

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.90

Eigen

Uncertain

0.40

Eigen_PC

Uncertain

0.43

FATHMM_MKL

Uncertain

0.94

LIST_S2

Uncertain

0.93

M_CAP

Pathogenic

0.56

MetaRNN

Pathogenic

0.98

MetaSVM

Uncertain

0.59

MutationAssessor

Pathogenic

4.5

PhyloP100

6.2

PrimateAI

Uncertain

0.69

PROVEAN

Pathogenic

-4.4

REVEL

Pathogenic

0.85

Sift

Uncertain

0.014

Sift4G

Uncertain

0.011

Polyphen

0.13

Vest4

0.84

MutPred

0.94

Loss of MoRF binding (P = 0.0508)

MVP

0.94

MPC

0.67

ClinPred

1.0

GERP RS

4.7

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.89

gMVP

0.96

Mutation Taster

=1/99

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.040

Details are displayed if max score is > 0.2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over