KCNQ1 Variant K427I Detail

We estimate the penetrance of LQTS for KCNQ1 K427I is 14%. We are unaware of any observations of this variant in individuals. K427I is not present in gnomAD. K427I has not been functionally characterized. This residue is located in a Non_Hotspot region for LQT1. In silico predictions, functional data (if available), and location in structure are equivalent to observing 1 individuals with LQT1 and 9 unaffected individuals. These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 K427I around 14% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-2.52 0.029 -2 0.667 4
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 LQT1 Other Disease
LITERATURE, COHORT, AND GNOMAD: - 0 0 0
VARIANT FEATURES ALONE: - 10 9 1 -
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.

K427I has 31 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. This results from the fact that the functional KV7.1 channel 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
427 0
426 4
428 4 D428G,
425 5 L425V,
429 5 N429S,
424 7 K424T,
430 7
423 8
431 8 V431L, V431L,
422 8 K422T, K422R,
432 8 T432I, T432A,
421 9 K421N, K421N,
433 9 P433A,
420 10 K420E, K420N, K420N,
434 10 G434R, G434R,
419 11
435 11
418 11 V418I,
436 11
417 12 V417M,
437 12 M437V,
416 13 V416M,
438 13
415 13
439 13
414 14
440 14
413 14 K413R,
441 14 P441S,
412 15 P412S,
442 15 H442R,