chr18-26862261-C-A

Position:

• chr18-26862261-C-A

Variant summary

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

The NM_001650.7(AQP4):​c.368G>T​(p.Cys123Phe) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,178 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., 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 (HGNC:):

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, 0.886

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
AQP4	NM_001650.7	c.368G>T	p.Cys123Phe	missense_variant	2/5	ENST00000383168.9	NP_001641.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
AQP4	ENST00000383168.9	c.368G>T	p.Cys123Phe	missense_variant	2/5	1	NM_001650.7	ENSP00000372654.4

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152178 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

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

GnomAD4 exome Cov.: 30

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152178 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74342

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

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

Nov 28, 2024

The c.368G>T (p.C123F) alteration is located in exon 2 (coding exon 2) of the AQP4 gene. This alteration results from a G to T substitution at nucleotide position 368, causing the cysteine (C) at amino acid position 123 to be replaced by a phenylalanine (F). 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	0.43
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.85	D;.;.;D
Eigen	Uncertain	0.64
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;.;D;T
M_CAP	Benign	0.074	D
MetaRNN	Pathogenic	0.89	D;D;D;D
MetaSVM	Uncertain	0.30	D
MutationAssessor	Benign	1.0	L;.;.;.
PrimateAI	Pathogenic	0.86	D
PROVEAN	Pathogenic	-5.8	D;.;.;.
REVEL	Pathogenic	0.85
Sift	Uncertain	0.021	D;.;.;.
Sift4G	Uncertain	0.021	D;D;D;.
Polyphen		0.99	D;.;.;.
Vest4		0.92
MutPred		0.67		Gain of MoRF binding (P = 0.2653);.;.;.;
MVP		0.96
MPC		0.72
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.88
gMVP		0.80

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs2054962133; hg19: chr18-24442225;