18-26862243-C-G

Position:

• chr18-26862243-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001650.7(AQP4):​c.386G>C​(p.Gly129Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: AQP4 NM_001650.7 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.56

Genes affected

AQP4 (HGNC:637): (aquaporin 4) This gene encodes a member of the aquaporin family of intrinsic membrane proteins that function as water-selective channels in the plasma membranes of many cells. This protein is the predominant aquaporin found in brain and has an important role in brain water homeostasis. Alternatively spliced transcript variants encoding different isoforms have been described for this gene. Additional isoforms, resulting from the use of alternative in-frame translation initiation codons, have also been described. Recent studies provided evidence for translational readthrough in this gene, and expression of C-terminally extended isoforms via the use of an alternative in-frame translation termination codon. [provided by RefSeq, Jun 2018]

AQP4-AS1 (HGNC:26399): (AQP4 antisense RNA 1)

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.88

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
AQP4	NM_001650.7	c.386G>C	p.Gly129Ala	missense_variant	2/5	ENST00000383168.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
AQP4	ENST00000383168.9	c.386G>C	p.Gly129Ala	missense_variant	2/5	1	NM_001650.7	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 13, 2023

The c.386G>C (p.G129A) alteration is located in exon 2 (coding exon 2) of the AQP4 gene. This alteration results from a G to C substitution at nucleotide position 386, causing the glycine (G) at amino acid position 129 to be replaced by an alanine (A). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.51
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.21
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.88	D;.;.;D
Eigen	Uncertain	0.65
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.98	D;.;D;D
M_CAP	Benign	0.060	D
MetaRNN	Pathogenic	0.88	D;D;D;D
MetaSVM	Uncertain	0.68	D
MutationAssessor	Benign	-0.010	N;.;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.79	T
PROVEAN	Pathogenic	-5.7	D;.;.;.
REVEL	Pathogenic	0.78
Sift	Benign	0.19	T;.;.;.
Sift4G	Benign	0.16	T;T;T;.
Polyphen		1.0	D;.;.;.
Vest4		0.84
MutPred		0.76		Loss of catalytic residue at I127 (P = 0.3305);.;.;.;
MVP		0.99
MPC		0.61
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.77
gMVP		0.92

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: rs1598516446; hg19: chr18-24442207;