KCNH2 Variant S26I

Summary of observed carriers, functional annotations, and structural context for KCNH2 S26I. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT2 penetrance

42%

90% CI: 20.1% – 65.2%

5/12 effective observations

Total carriers

2

2 LQT2 · 0 unaffected

Functional studies

0

Publications with functional data

S26I has not been reported 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 9%. 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 (%)
-2.765 0.0 -4 0.714 84

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
11854117 2002 2 0 2
15840476 2005 1 0 1
Literature, cohort, and gnomAD – 2 0 2 –
Variant features alone – 10 7 3 –

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

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 S26I.
Neighbour residue Distance (Å) Observed variants
26 0 S26I,
27 4 R27X, R27P,
25 5 Q25P,
24 5
23 6
28 7 K28E,
22 8 F22Y, F22S,
47 8 G47C, G47V,
45 9 N45D, N45K, N45K,
29 9 F29L, F29V, F29S, F29L, F29L,
130 10 E130K,
128 10 N128S,
21 10
46 10 D46Y, D46E, D46E,
50 11 E50X,
19 11 I19F,
129 12 F129C,
48 12
20 13 R20G, R20L,
131 13 V131L, V131L, V131fsX,
51 13
18 13 I18M,
49 14 C49R, C49G,
43 14 Y43D, Y43C,
30 14 I30Del, I30T
44 14 C44F, C44X, C44W,
111 14 D111V,
126 14
127 15
109 15 L109X, L109Q, L109P,