KCNH2 Variant E698X

Summary of observed carriers, functional annotations, and structural context for KCNH2 E698X. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT2 penetrance

%

NA/NA effective observations

Total carriers

2

2 LQT2 · 0 unaffected

Functional studies

2

Publications with functional data

E698X has not been reported in gnomAD. This residue resides in a None region for LQT2.

We have tested the trafficking efficiency of this variant: 0% of WT with a standard error of 0%. In our analysis we used SE < 20% as 'high quality'. Approximately below 50% of WT is considered PS3 moderate and below 30% is PS3 strong.

In silico predictors

Variant-level computational predictors.
PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density LQT2 (%)
None None None None

PROVEAN scores below -2 suggest deleterious impact. REVEL scores above 0.5–0.75 are often interpreted as likely pathogenic. PolyPhen-2 scores above 0.85 are typically pathogenic. BLAST-PSSM reflects evolutionary conservation; more negative values indicate rarer substitutions. Penetrance density summarises neighbouring residue risk (Kroncke et al. 2019).

Reported carrier data

Observed carriers by publication or cohort.
Source Year Carriers Unaffected LQT2 Other Disease
19038855 2009 1 0 1 Seizure
12402336 2002 1 0 1
19127321 2008 3 0 1
Literature, cohort, and gnomAD – 2 0 2 –
Variant features alone – 10 NA NA –

Totals may differ from individual publications due to duplicate patients removed during curation.

Functional data

Functional assay results from published electrophysiology studies. Steady state (S.S.) and peak tail current are relative % to wildtype (100% being no different from wildtype). V1/2 activation and inactivation are the voltages at which half of the maximal current is reached, in mV. Recovery from inactivation and deactivation time are ratios of characteristic time constants with wildtype. HM indicates homomeric channels, HT indicates heteromeric channels.

Homomeric channel data

Published electrophysiology measurements (homomeric).
PubMed ID Cell Type S.S Peak (%WT) Peak Tail IKr (%WT) V1/2 Act. V1/2 Inact. Recov. Inact. Deactivation (%WT)
19324319 HEK293 0 None None None None
24366185 HEK293 0 None None None None

Heteromeric channel data

Published electrophysiology measurements (heteromeric).
PubMed ID Cell Type S.S Peak (%WT) Peak Tail IKr (%WT) V1/2 Act. V1/2 Inact. Deactivation (%WT)
19324319 HEK293 None None None
24366185 HEK293 None None None