KCNH2 Variant S543G

Summary of observed carriers, functional annotations, and structural context for KCNH2 S543G. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT2 penetrance

17%

1/10 effective observations

Total carriers

0

0 LQT2 · 0 unaffected

Functional studies

1

Publications with functional data

S543G has not been reported in gnomAD. This residue resides in a Mild_Hotspot region for LQT2.

We have tested the trafficking efficiency of this variant: 65% of WT with a standard error of 14%. 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 1 individuals with LQT2 and 9 unaffected individuals.

In silico predictors

Variant-level computational predictors.
PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density LQT2 (%)
None None None None 33

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
Literature, cohort, and gnomAD 0 0 0
Variant features alone 10 9 1

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)
24407947 Xeno -12.6 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)
24407947 Xeno 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 S543G.
Neighbour residue Distance (Å) Observed variants
543 0 S543fsX,
540 5 D540fsX,
544 5 E544A, E544fsX,
539 6
549 6 V549M,
542 6
674 7 H674Y, H674fsX,
548 7
546 7
545 7
541 8 R541C, R541H,
552 9 L552S,
3 9
547 9 A547T,
673 10
670 10
412 10 W412X,
665 10 R665Q,
677 11 M677T,
538 11
535 11 V535M,
662 11
536 11 A536X,
553 11 L553V,
550 11
681 11 R681W,
678 11
671 11 A671G, A671Del,
551 12 F551L, F551L, F551L,
675 12
411 12
415 12
658 13
408 13
666 13
4 13
669 13 G669R, G669C, G669X,
702 13
667 14 Y667X,
537 14 R537W,
659 14
661 14 A661V,
555 14
556 14
705 15 W705fsX, W705X
676 15 Q676fsX, Q676X,
698 15 E698K, E698X,
672 15 R672C, R672H,
655 15