KCNH2 Variant A558G Detail

We estimate the penetrance of LQTS for KCNH2 A558G is 59%. We are unaware of any observations of this variant in individuals. A558G is not present in gnomAD. A558G has not been functionally characterized. This residue is located in a Hotspot region for LQT2. In silico predictions, functional data (if available), and location in structure are equivalent to observing 5 individuals with LQT2 and 5 unaffected individuals.These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 A558G around 59% (5/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-3.459 0.584 0 0.874 67
PROVEAN scores less than -2 are considered deleterious. REVEL scores higher than 0.5 or 0.75 are considered likely pathogenic (higher sensitivity with the former cutoff, higher specificity with the latter cutoff). A PolyPhen-2 score of 0.85 or greater is considered likely pathogenic. BLAST-PSSM reflects the evolutionary conservation of residue substitutions, more negative numbers indicate fewer observations of the specific substitution than is expected. Penetrance density is our previously published method to calculate the average LQTS probability density in a shell of residues surrounding a residue of interest (Kroncke et al. 2019).

Reported Carrier Data

PubMed ID Year Carriers Unaffected LQT2 Other Disease
LITERATURE, COHORT, AND GNOMAD: - 0 0 0 -
VARIANT FEATURES ALONE: - 10 5 5 -
Summary totals might not agree with the literature table because of duplicate patients, which were excluded from the total counts. We do not distinguish here between multiple missense codons. Missense variants are combined across degenerate codon substitutions since codon-level data were not consistently available for curation.

A558G has 64 previously observed neighbors within 15 angstroms

A residue within a folded protein on average has nearest neighbors that fall roughly into two shells: a "nearest" neighbor around 5-6 angstroms and a second shell around 11 angstroms. NOTE: 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 15A window. All variants shown in the rightmost column have been observed in at least one individual in the literature or gnomAD.

Neighbor Distance (Angstroms) Variants Observed in Individuals
558 0 A558V, A558P, A558E,
559 4 L559F, L559H,
557 5
561 5 A561V, A561P, A561T,
560 5 I560fsX, I560M,
556 6
555 6
562 6 H562Q, H562Q, H562R, H562P,
619 7
554 7
563 8 W563X, W563C, W563G, W563C,
615 8 L615V, L615F,
646 8
423 9
618 9 T618S, T618S,
564 10 L564L,
422 10 A422T,
622 10 L622F,
419 10
642 10 I642Del, I642V,
553 10 L553V,
565 10
552 11 L552S,
551 11 F551L, F551L, F551L,
651 11 M651K,
655 11
611 11 Y611D,
645 11 M645L, M645I, M645I, M645L, M645I, M645V, M645R,
566 12 C566G, C566S, C566R, C566F, C566S,
623 12 T623I,
649 12
643 12
656 12 F656L, F656L, F656L,
614 12 A614T, A614V,
426 13 P426H,
620 13 S620I, S620G,
648 13 G648A,
550 13
652 13 Y652X,
424 13
612 13 V612L, V612A, V612L,
647 13
621 13 S621N, S621R, S621R, S621R,
650 13 L650X,
647 13
644 13 V644F, V644I,
639 13 I639F, I639N,
421 14 T421M, T421fsX,
418 14
617 14 F617V, F617L, F617L, F617L,
532 14
567 14 I567M, I567T,
616 14 Y616S,
427 14 Y427C, Y427H, Y427S,
641 14 S641F, S641P,
648 14 G648A,
644 14 V644F, V644I,
415 14
420 14 Y420C,
425 14
416 15
529 15
659 15
654 15