KCNH2 Variant N633D

Summary of observed carriers, functional annotations, and structural context for KCNH2 N633D. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT2 penetrance

41%

4/11 effective observations

Total carriers

1

1 LQT2 · 0 unaffected

Functional studies

1

Publications with functional data

N633D has not been reported in gnomAD. This residue resides in a Hotspot region for LQT2.

We have tested the trafficking efficiency of this variant: 16% of WT with a standard error of 10%. 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.

Variant features alone are equivalent to phenotyping 3 individuals with LQT2 and 7 unaffected individuals.

In silico predictors

Variant-level computational predictors.
PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density LQT2 (%)
-4.801 0.94 1 0.867 89

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
18593567 2008 1 0 1
16155735 2005 1 0 1
Literature, cohort, and gnomAD 1 0 1
Variant features alone 10 7 3

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)
18593567 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)
18593567 HEK293 None None None

Nearby variants

Neighbouring residues within 15 Ångström provide structural context. Variants listed in the right-most column have been observed clinically or in gnomAD. Note that some residues appear multiple times at different distances since the functional KV11.1 channel (protein product of KCNH2/hERG) is a homotetramer and occasionally the same residue from multiple subunits is present within the 15Å window.

Previously observed variants near N633D.
Neighbour residue Distance (Å) Observed variants
633 0 N633I, N633S, N633D,
632 5 P632S, P632A,
634 5 T634S, T634I, T634P, T634S, T634A,
584 6 G584R, G584S, G584C,
631 6 S631F,
592 6 Q592X,
637 6 E637K, E637G, E637X,
629 6 N629I, N629T, N629D, N629K, N629K, N629S,
638 6 K638R, K638D, K638E, K638Del,
593 7 I593K, I593X, I593R, I593V, I593T,
583 7 I583V,
635 8 N635I,
588 9 N588D, N588K, N588K,
589 9 L589P,
585 9 W585C, W585C,
636 9
616 9 Y616S,
613 9 T613M, T613K, T613L, T613A,
630 9 V630I, V630A, V630T,
630 10 V630I, V630A, V630T,
628 10 G628D, G628R, G628Del, G628A, G628S, G628V,
627 10 F627L, F627L, F627L, F627X, F627fsX,
609 10 D609N, D609G,
594 11
590 11 G590V, G590D,
612 11 V612L, V612A, V612L,
587 11
568 11 W568C, W568C,
641 11 S641P, S641F,
588 11 N588D, N588K, N588K,
628 11 G628D, G628R, G628Del, G628A, G628S, G628V,
591 11 D591H, D591N,
586 11 L586M,
639 11 I639F, I639N,
572 12 G572S, G572D, G572R, G572C,
571 12 I571V, I571L,
595 12 K595E, K595N, K595N,
617 12 F617L, F617V, F617L, F617L,
575 12 E575K,
640 12 F640L, F640V, F640L, F640L, F640Del,
589 13 L589P,
629 13 N629I, N629T, N629D, N629K, N629K, N629S,
631 13 S631F,
614 13 A614T, A614V,
606 13 S606F, S606P, S606Del,
605 13 P605L,
642 13 I642Del, I642V,
585 13 W585C, W585C,
617 13 F617L, F617V, F617L, F617L,
591 13 D591H, D591N,
610 13
577 14
592 14 Q592X,
608 14
626 14 G626V, G626S, G626A,
586 14 L586M,
576 14
615 14 L615F, L615V,
620 14 S620G, S620I,
590 14 G590V, G590D,
626 15 G626V, G626S, G626A,
613 15 T613M, T613K, T613L, T613A,
621 15 S621R, S621R, S621R, S621N
614 15 A614T, A614V,