3-49026757-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PP2 PP3_Moderate

The NM_000884.3(IMPDH2):c.749T>G(p.Ile250Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000547 in 1,461,892 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I250M) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: IMPDH2 NM_000884.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.19

Genes affected

IMPDH2 (HGNC:6053): (inosine monophosphate dehydrogenase 2) This gene encodes the rate-limiting enzyme in the de novo guanine nucleotide biosynthesis. It is thus involved in maintaining cellular guanine deoxy- and ribonucleotide pools needed for DNA and RNA synthesis. The encoded protein catalyzes the NAD-dependent oxidation of inosine-5'-monophosphate into xanthine-5'-monophosphate, which is then converted into guanosine-5'-monophosphate. This gene is up-regulated in some neoplasms, suggesting it may play a role in malignant transformation. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PP2: Missense variant where missense usually causes diseases, IMPDH2
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.914

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
IMPDH2	NM_000884.3	c.749T>G	p.Ile250Ser	missense_variant	7/14	ENST00000326739.9
IMPDH2	NM_001410759.1	c.749T>G	p.Ile250Ser	missense_variant	7/15
IMPDH2	NM_001410760.1	c.674T>G	p.Ile225Ser	missense_variant	6/14
IMPDH2	NM_001410761.1	c.674T>G	p.Ile225Ser	missense_variant	6/13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
IMPDH2	ENST00000326739.9	c.749T>G	p.Ile250Ser	missense_variant	7/14	1	NM_000884.3	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000159 AC: 4 AN: 251496 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135922

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.000298

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000879

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461892 Hom.: 0 Cov.: 33 AF XY: 0.00000688 AC XY: 5 AN XY: 727246

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.000268

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000487 Hom.: 0

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 11, 2022

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. This variant has not been reported in the literature in individuals affected with IMPDH2-related conditions. This variant is present in population databases (rs767704477, gnomAD 0.03%). This sequence change replaces isoleucine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 250 of the IMPDH2 protein (p.Ile250Ser). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.83
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
Cadd	Pathogenic	27
Dann	Uncertain	0.99
DEOGEN2	Pathogenic	0.85	D;.
Eigen	Uncertain	0.63
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;D
M_CAP	Uncertain	0.17	D
MetaRNN	Pathogenic	0.91	D;D
MetaSVM	Uncertain	0.36	D
MutationAssessor	Uncertain	2.7	M;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-5.8	D;D
REVEL	Pathogenic	0.88
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		0.40	B;.
Vest4		0.97
MutPred		0.79		Gain of disorder (P = 0.0034);.;
MVP		0.93
MPC		1.2
ClinPred		0.88	D
GERP RS		6.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.8
Varity_R		0.95
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: rs767704477; hg19: chr3-49064190; COSMIC: COSV58708559; COSMIC: COSV58708559;