KCNH2 Variant F508L Detail

We estimate the penetrance of LQTS for KCNH2 F508L is 36%. We are unaware of any observations of this variant in individuals. F508L is not present in gnomAD. F508L 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 3 individuals with LQT2 and 7 unaffected individuals.These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 F508L around 36% (3/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-5.427 0.225 0 0.836 45
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
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.

F508L has 29 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
508 0
507 5 P507L, P507S,
506 6 I506V,
510 6
509 6 D509N,
524 7
525 8 K525N, K525N,
521 9
505 9 A505V,
522 10 G522E,
528 10 R528P, R528W, R528X,
527 10
503 10
504 10 A504V,
460 11 D460fsX,
523 11
526 11
520 12
502 12 M502I, M502I, M502I,
457 13 L457P,
456 13 D456Y,
531 14 R531Del, R531W, R531Q,
464 14 I464X,
425 14
530 15
461 15
429 15 A429P, A429V,
463 15 F463L, F463L, F463L,
459 15