rs886041796

chr20-44624275-AC-Achr20-44624275-AC-ACC

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000022.4(ADA):c.532del(p.Val178Ter) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,172 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★★). Synonymous variant affecting the same amino acid position (i.e. V178V) has been classified as Benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: ADA NM_000022.4 frameshift
• Clinical Significance: Pathogenic reviewed by expert panel P:8
• Conservation: PhyloP100: 7.30

Genes affected

ADA (HGNC:186): (adenosine deaminase) This gene encodes an enzyme that catalyzes the hydrolysis of adenosine to inosine in the purine catabolic pathway. Various mutations have been described for this gene and have been linked to human diseases related to impaired immune function such as severe combined immunodeficiency disease (SCID) which is the result of a deficiency in the ADA enzyme. In ADA-deficient individuals there is a marked depletion of T, B, and NK lymphocytes, and consequently, a lack of both humoral and cellular immunity. Conversely, elevated levels of this enzyme are associated with congenital hemolytic anemia. [provided by RefSeq, Sep 2019]

PKIG (HGNC:9019): (cAMP-dependent protein kinase inhibitor gamma) This gene encodes a member of the protein kinase inhibitor family. Studies of a similar protein in mice suggest that this protein acts as a potent competitive cAMP-dependent protein kinase inhibitor, and is a predominant form of inhibitor in various tissues. The encoded protein may be involved in osteogenesis. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2013]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 20-44624275-AC-A is Pathogenic according to our data. Variant chr20-44624275-AC-A is described in ClinVar as [Pathogenic]. Clinvar id is 505549.Status of the report is reviewed_by_expert_panel, 3 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ADA	NM_000022.4	c.532del	p.Val178Ter	frameshift_variant	6/12	ENST00000372874.9
ADA	NM_001322051.2	c.532del	p.Val178Ter	frameshift_variant	6/11
ADA	NM_001322050.2	c.127del	p.Val43Ter	frameshift_variant	5/11
ADA	NR_136160.2	n.624del		non_coding_transcript_exon_variant	6/11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ADA	ENST00000372874.9	c.532del	p.Val178Ter	frameshift_variant	6/12	1	NM_000022.4	P4

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152172 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000193

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251362 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135874

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152172 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74336

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000193

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8

Revision: reviewed by expert panel

Submissions by phenotype

Severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-negative, due to adenosine deaminase deficiency Pathogenic:7

Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Nov 13, 2019	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Sep 20, 2017	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Feb 03, 2017	The p.Val178X variant in ADA has not been previously reported in individuals wit h adenosine deaminase (ADA) deficiency, but was identified in 2/18938 East Asian individuals by the Genome Aggregation Database (gnomAD, http://gnomad.broadinst itute.org/). This variant is a deletion of 1 nucleotide at position 532, which g enerates a premature termination codon at amino acid position 178. Loss of funct ion of the ADA gene is an established disease mechanism in severe combined immun odeficiency due to adenosine deaminase deficiency. In summary, although addition al studies are required to fully establish its clinical significance, the p.Val1 78X variant is likely pathogenic due to its predicted impact to the protein. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Aug 10, 2021	- -
Pathogenic, reviewed by expert panel	curation	ClinGen Severe Combined Immunodeficiency Variant Curation Expert Panel, ClinGen	Oct 10, 2023	The NM_000022.4:c.532del (p.Val178*) variant in ADA creates a premature translational stop signal in exon 6 (of 12) and is expected to result in nonsense-mediated decay in a loss of function gene (PVS1). This variant was reported as homozygous in an infant with T-B- severe combined immunodeficiency (SCID) (PMID: 30290665) (PP4, PM3_Supporting). The highest population minor allele frequency for this variant in gnomAD v2.1.1 is 0.0001 (2/19948 alleles) in the East Asian population, which is lower than the ADA cutoff (gnomAD popmax filtering allele frequency <0.0001742). So PM2 is met. In summary, this variant meets the criteria to be classified as pathogenic for SCID. ACMG/AMP criteria applied, as specified by the ClinGen SCID-VCEP: PVS1, PP4, PM3_Supporting, PM2_Supporting (SCID VCEP specifications version 1.0). -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Apr 06, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	May 02, 2023	For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 505549). This variant has not been reported in the literature in individuals affected with ADA-related conditions. This variant is present in population databases (no rsID available, gnomAD 0.01%). This sequence change creates a premature translational stop signal (p.Val178*) in the ADA gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in ADA are known to be pathogenic (PMID: 26255240, 26376800). -

Severe combined immunodeficiency disease Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Dec 03, 2021

Variant summary: ADA c.532delG (p.Val178X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant allele was found at a frequency of 4e-06 in 251362 control chromosomes. c.532delG has been reported in the literature in a homozygous individual affected with Severe Combined Immunodeficiency (Chi_2018). To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Five Six submitters have provided clinical-significance assessments for this variant in ClinVar after 2014 without evidence for independent evaluation, and classified the variant as pathogenic (n=2) / likely pathogenic (n=3). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs886041796; hg19: chr20-43252916;