KCNH2 Variant V612L

Summary of observed carriers, functional annotations, and structural context for KCNH2 V612L. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT2 penetrance

37%

5/14 effective observations

Total carriers

4

2 LQT2 · 1 unaffected

Functional studies

2

Publications with functional data

V612L is present in 1 alleles in gnomAD. This residue resides in a Hotspot region for LQT2.

We have tested the trafficking efficiency of this variant: 0% of WT with a standard error of 19%. 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 (%)
-2.595 0.338 1 0.76 86

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
9544837 1998 3 1 2
Literature, cohort, and gnomAD 4 1 2
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)
11524404 Xeno 0 None None None None
15851652 HEK293 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)
11524404 Xeno 68 25 1.1 -1.3 None
15851652 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 V612L.
Neighbour residue Distance (Å) Observed variants
612 0 V612L, V612L, V612A,
613 4 T613M, T613A, T613L, T613K,
611 5 Y611D,
609 5 D609G, D609N,
615 5 L615F, L615V,
614 6 A614T, A614V,
638 6 K638Del, K638R, K638E, K638D,
635 6 N635I,
608 6
639 7 I639F, I639N,
616 7 Y616S,
610 8
642 8 I642Del, I642V,
565 9
607 9
636 9
634 9 T634A, T634S, T634I, T634P, T634S,
606 9 S606F, S606P, S606Del,
641 10 S641P, S641F,
617 10 F617L, F617L, F617L, F617V,
632 10 P632S, P632A,
618 10 T618S, T618S,
619 10
562 10 H562Q, H562Q, H562P, H562R,
637 10 E637G, E637X, E637K,
589 11 L589P,
633 11 N633D, N633I, N633S,
569 11 Y569X, Y569C, Y569H,
566 11 C566F, C566S, C566G, C566S, C566R,
431 11 F431L, F431L, F431L,
630 11 V630I, V630A, V630T,
427 11 Y427S, Y427H, Y427C,
561 11 A561T, A561V, A561P,
568 11 W568C, W568C,
585 11 W585C, W585C,
605 12 P605L,
593 12 I593K, I593X, I593V, I593T, I593R,
629 12 N629I, N629D, N629S, N629K, N629K, N629T,
620 12 S620I, S620G,
640 12 F640Del, F640L, F640L, F640L, F640V
645 12 M645I, M645I, M645L, M645V, M645R, M645I, M645L,
586 12 L586M,
643 12
564 13 L564L,
627 13 F627L, F627X, F627L, F627L, F627fsX,
558 13 A558P, A558V, A558E,
592 13 Q592X,
631 14 S631F,
423 14
430 14
567 14 I567T, I567M,
595 14 K595E, K595N, K595N,
646 14
644 14 V644I, V644F,
590 14 G590V, G590D,
621 14 S621R, S621R, S621N, S621R,
628 14 G628V, G628R, G628S, G628D, G628A, G628Del,
631 15 S631F,
588 15 N588K, N588D, N588K,
426 15 P426H,
570 15
559 15 L559H, L559F,
571 15 I571V, I571L,
604 15 G604S, G604C, G604D,