Genetic Variant NM_022168.4:c.1762_1764delAAA (chr2-162278205-CTTT-C) – ACMG Classification: Uncertain_significance (3 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2PM4_Supporting

The NM_022168.4(IFIH1):c.1762_1764delAAA(p.Lys588del) variant causes a conservative inframe deletion, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000691 in 1,447,786 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

IFIH1
NM_022168.4 conservative_inframe_deletion, splice_region

Scores

Not classified

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 2.56

Publications

4 publications found

Variant links:

Genes affected

IFIH1 (HGNC:18873): (interferon induced with helicase C domain 1) IFIH1 encodes MDA5 which is an intracellular sensor of viral RNA that triggers the innate immune response. Sensing RNA length and secondary structure, MDA5 binds dsRNA oligonucleotides with a modified DExD/H-box helicase core and a C-terminal domain, thus leading to a proinflammatory response that includes interferons. It has been shown that Coronaviruses (CoVs) as well as various other virus families, are capable of evading the MDA5-dependent interferon response, thus impeding the activation of the innate immune response to infection. MDA5 has also been shown to play an important role in enhancing natural killer cell function in malaria infection. In addition to its protective role in antiviral responses, MDA5 has been implicated in autoimmune and autoinflammatory diseases such as type 1 diabetes, systemic lupus erythematosus, and Aicardi-Goutieres syndrome[provided by RefSeq, Jul 2020]

IFIH1 Gene-Disease associations (from GenCC):

Aicardi-Goutieres syndrome 7
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, Illumina, Labcorp Genetics (formerly Invitae), G2P
Singleton-Merten syndrome 1
Inheritance: AD Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
Aicardi-Goutieres syndrome
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Singleton-Merten dysplasia
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
immunodeficiency 95
Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics

IFIH1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PM4

Nonframeshift variant in NON repetitive region in NM_022168.4. Strenght limited to Supporting due to length of the change: 1aa.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
IFIH1	NM_022168.4 link	c.1762_1764delAAA	p.Lys588del	conservative_inframe_deletion, splice_region_variant	Exon 9 of 16	ENST00000649979.2	NP_071451.2	Q9BYX4-1
IFIH1	XM_047445407.1 link	c.1045_1047delAAA	p.Lys349del	conservative_inframe_deletion, splice_region_variant	Exon 8 of 15		XP_047301363.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IFIH1	ENST00000649979.2 link	c.1762_1764delAAA	p.Lys588del	conservative_inframe_deletion, splice_region_variant	Exon 9 of 16		NM_022168.4	ENSP00000497271.1		Q9BYX4-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000427

AC:

AN:

234356

AF XY:

0.00000787

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000590

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.91e-7

AC:

AN:

1447786

Hom.:

AF XY:

0.00000139

AC XY:

AN XY:

720078

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:

32558

American (AMR)

AF:

0.00

AC:

AN:

41626

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25778

East Asian (EAS)

AF:

0.0000254

AC:

AN:

39322

South Asian (SAS)

AF:

0.00

AC:

AN:

83336

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53214

Middle Eastern (MID)

AF:

0.00

AC:

AN:

4996

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1107190

Other (OTH)

AF:

0.00

AC:

AN:

59766

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.275

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

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

2.6

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.020

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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over