18-26856489-T-C

Position:

• chr18-26856489-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001650.7(AQP4):​c.694A>G​(p.Ile232Val) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,808 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 17/23 in silico tools predict a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: AQP4 NM_001650.7 missense, splice_region
• Scores: Splicing: ADA: 0.00001244
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.87

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 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.15891787).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
AQP4	NM_001650.7	c.694A>G	p.Ile232Val	missense_variant, splice_region_variant	5/5	ENST00000383168.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
AQP4	ENST00000383168.9	c.694A>G	p.Ile232Val	missense_variant, splice_region_variant	5/5	1	NM_001650.7	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461808 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727212

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

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

Aug 30, 2022

The c.694A>G (p.I232V) alteration is located in exon 5 (coding exon 5) of the AQP4 gene. This alteration results from a A to G substitution at nucleotide position 694, causing the isoleucine (I) at amino acid position 232 to be replaced by a valine (V). 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	Benign	0.074
BayesDel_addAF	Benign	-0.12	T
BayesDel_noAF	Benign	-0.42
CADD	Benign	12
DANN	Benign	0.73
DEOGEN2	Uncertain	0.43	T;.;.
Eigen	Benign	-0.66
Eigen_PC	Benign	-0.42
FATHMM_MKL	Benign	0.62	D
LIST_S2	Benign	0.82	T;.;T
M_CAP	Benign	0.011	T
MetaRNN	Benign	0.16	T;T;T
MetaSVM	Benign	-0.89	T
MutationAssessor	Benign	-0.41	N;.;.
MutationTaster	Benign	0.98	D;D;D
PrimateAI	Uncertain	0.59	T
PROVEAN	Benign	0.36	N;.;.
REVEL	Benign	0.19
Sift	Benign	1.0	T;.;.
Sift4G	Benign	1.0	T;T;T
Polyphen		0.0	B;.;.
Vest4		0.11
MutPred		0.48		Loss of sheet (P = 0.302);.;.;
MVP		0.79
MPC		0.10
ClinPred		0.15	T
GERP RS		2.2
Varity_R		0.059
gMVP		0.37

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.000012
dbscSNV1_RF	Benign	0.0020
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

No publications associated with this variant yet.

Other links and lift over

hg19: chr18-24436453;