chr16-28932061-G-C

Position:

• chr16-28932061-G-C

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001770.6(CD19):​c.61G>C​(p.Glu21Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,816 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CD19 NM_001770.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.837

Genes affected

CD19 (HGNC:1633): (CD19 molecule) This gene encodes a member of the immunoglobulin gene superfamily. Expression of this cell surface protein is restricted to B cell lymphocytes. This protein is a reliable marker for pre-B cells but its expression diminishes during terminal B cell differentiation in antibody secreting plasma cells. The protein has two N-terminal extracellular Ig-like domains separated by a non-Ig-like domain, a hydrophobic transmembrane domain, and a large C-terminal cytoplasmic domain. This protein forms a complex with several membrane proteins including complement receptor type 2 (CD21) and tetraspanin (CD81) and this complex reduces the threshold for antigen-initiated B cell activation. Activation of this B-cell antigen receptor complex activates the phosphatidylinositol 3-kinase signalling pathway and the subsequent release of intracellular stores of calcium ions. This protein is a target of chimeric antigen receptor (CAR) T-cells used in the treatment of lymphoblastic leukemia. Mutations in this gene are associated with the disease common variable immunodeficiency 3 (CVID3) which results in a failure of B-cell differentiation and impaired secretion of immunoglobulins. CVID3 is characterized by hypogammaglobulinemia, an inability to mount an antibody response to antigen, and recurrent bacterial infections. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Jul 2020]

RABEP2 (HGNC:24817): (rabaptin, RAB GTPase binding effector protein 2) Predicted to enable GTPase activator activity and growth factor activity. Involved in regulation of cilium assembly. Located in cytosol; intracellular membrane-bounded organelle; and microtubule organizing center. [provided by Alliance of Genome Resources, Apr 2022]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.030639976).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CD19	NM_001770.6	c.61G>C	p.Glu21Gln	missense_variant	1/15	ENST00000538922.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CD19	ENST00000538922.8	c.61G>C	p.Glu21Gln	missense_variant	1/15	5	NM_001770.6	P3
CD19	ENST00000324662.8	c.61G>C	p.Glu21Gln	missense_variant	1/15	1		A2
RABEP2	ENST00000566762.1	c.-150+4203C>G		intron_variant		4
CD19	ENST00000565089.5	n.97G>C		non_coding_transcript_exon_variant	1/13	2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461816 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727220

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

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.: 31

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Immunodeficiency, common variable, 3 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 08, 2022

This sequence change replaces glutamic acid, which is acidic and polar, with glutamine, which is neutral and polar, at codon 21 of the CD19 protein (p.Glu21Gln). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CD19-related conditions. ClinVar contains an entry for this variant (Variation ID: 885125). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The glutamine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.084
BayesDel_addAF	Benign	-0.35	T
BayesDel_noAF	Benign	-0.74
CADD	Benign	7.3
DANN	Benign	0.60
DEOGEN2	Benign	0.31	.;T;.
Eigen	Benign	-1.5
Eigen_PC	Benign	-1.3
FATHMM_MKL	Benign	0.0015	N
LIST_S2	Benign	0.34	T;T;.
M_CAP	Benign	0.0044	T
MetaRNN	Benign	0.031	T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	-1.5	N;N;N
MutationTaster	Benign	1.0	N;N;N
PrimateAI	Benign	0.26	T
PROVEAN	Benign	1.6	N;N;N
REVEL	Benign	0.052
Sift	Benign	1.0	T;T;T
Sift4G	Benign	1.0	T;T;T
Polyphen		0.0	.;B;.
Vest4		0.14
MutPred		0.22		Loss of disorder (P = 0.0918);Loss of disorder (P = 0.0918);Loss of disorder (P = 0.0918);
MVP		0.35
MPC		0.25
ClinPred		0.048	T
GERP RS		2.1
Varity_R		0.22
gMVP		0.44

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: rs771929657; hg19: chr16-28943382;