chr7-128394575-C-A

Variant names:

• chr7-128394575-C-A
• rs2228075
• NM_000883.4:c.1575G>T

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 1P and 4B. PP3 BS2

The NM_000883.4(IMPDH1):​c.1575G>T​(p.Ala525Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,613,436 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. A525A) has been classified as Benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 31)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: IMPDH1 NM_000883.4 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -2.88
• Publications: 30 publications found

Genes affected

IMPDH1 (HGNC:6052): (inosine monophosphate dehydrogenase 1) The protein encoded by this gene acts as a homotetramer to regulate cell growth. The encoded protein is an enzyme that catalyzes the synthesis of xanthine monophosphate (XMP) from inosine-5'-monophosphate (IMP). This is the rate-limiting step in the de novo synthesis of guanine nucleotides. Defects in this gene are a cause of retinitis pigmentosa type 10 (RP10). Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Dec 2008]

IMPDH1 Gene-Disease associations (from GenCC):

• IMPDH1-related retinopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• Leber congenital amaurosis 11

  Inheritance: AD Classification: DEFINITIVE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), G2P
• retinitis pigmentosa 10

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• Leber congenital amaurosis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• retinitis pigmentosa

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

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

• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• BS2: High AC in GnomAdExome4 at 5 AD gene.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000883.4. 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
	IMPDH1	NM_000883.4	MANE Select	c.1575G>T	p.Ala525Ala	synonymous	Exon 15 of 17	NP_000874.2
	IMPDH1	NM_001102605.2		c.1545G>T	p.Ala515Ala	synonymous	Exon 14 of 16	NP_001096075.1	P20839-5
	IMPDH1	NM_001142576.2		c.1476G>T	p.Ala492Ala	synonymous	Exon 14 of 16	NP_001136048.1	P20839-7

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	IMPDH1	ENST00000338791.11	TSL:2 MANE Select	c.1575G>T	p.Ala525Ala	synonymous	Exon 15 of 17	ENSP00000345096.6	P20839-6
	IMPDH1	ENST00000348127.11	TSL:1	c.1467G>T	p.Ala489Ala	synonymous	Exon 13 of 15	ENSP00000265385.8	P20839-3
	IMPDH1	ENST00000955327.1		c.1563G>T	p.Ala521Ala	synonymous	Exon 13 of 15	ENSP00000625386.1

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151874 Hom.: 0 Cov.: 31

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461562 Hom.: 0 Cov.: 38 AF XY: 0.00000413 AC XY: 3 AN XY: 727084

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

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

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

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53180

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5736

European-Non Finnish (NFE) AF: 0.00000450 AC: 5 AN: 1111970

Other (OTH) AF: 0.00 AC: 0 AN: 60388

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151874 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 74146

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

African (AFR) AF: 0.00 AC: 0 AN: 41330

American (AMR) AF: 0.00 AC: 0 AN: 15270

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5150

South Asian (SAS) AF: 0.00 AC: 0 AN: 4816

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10574

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 67948

Other (OTH) AF: 0.00 AC: 0 AN: 2090

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 3739

Bravo AF: 0.00000756

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.68
CADD	Benign	7.1
DANN	Benign	0.48
PhyloP100		-2.9

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.54		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.54		Position offset: -25

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

Other links and lift over

dbSNP: rs2228075; hg19: chr7-128034629;