KCNQ1 Variant K420E

Summary of observed carriers, functional annotations, and structural context for KCNQ1 K420E. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT1 penetrance

30%

3/11 effective observations

Total carriers

1

0 LQT1 · 1 unaffected

Functional studies

0

Publications with functional data

K420E is present in 1 alleles in gnomAD. This residue resides in a Mild_Hotspot region for LQT1.

Variant features alone are equivalent to phenotyping 3 individuals with LQT1 and 7 unaffected individuals.

In silico predictors

Variant-level computational predictors.
PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density LQT1 (%)
-1.88 0.077 0 0.664 39

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 LQT1 Other Disease
Literature, cohort, and gnomAD – 1 1 0 –
Variant features alone – 15 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.

Previously observed variants near K420E.
Neighbour residue Distance (Å) Observed variants
420 0 K420E, K420N, K420N,
419 4
421 4 K421N, K421N,
418 5 V418I,
422 5 K422T, K422R,
417 7 V417M,
423 7
416 8 V416M,
424 8 K424T,
415 8
425 8 L425V,
414 9
426 9
413 10 K413R,
427 10
412 11 P412S,
428 11 D428G,
411 11
429 11 N429S,
410 12
430 12
409 13
431 13 V431L, V431L,
408 13 P408A,
432 13 T432I, T432A
407 14
433 14 P433A,
406 14
434 14 G434R, G434R,
405 15
435 15