KCNQ1 Variant A370S Detail

We estimate the penetrance of LQTS for KCNQ1 A370S is 28%. We are unaware of any observations of this variant in individuals. A370S is not present in gnomAD. A370S has not been functionally characterized. This residue is located in a Mild_Hotspot region for LQT1. In silico predictions, functional data (if available), and location in structure are equivalent to observing 2 individuals with LQT1 and 8 unaffected individuals. These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 A370S around 28% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-2.25 0.997 1 0.865 36
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 8 2 -
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.

A370S has 35 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
370 0 A370V,
371 4 A371T,
369 4
373 5 S373P,
372 5
529 5
368 6
525 6 A525T, A525V,
528 6
374 6 L374H, L374F,
367 7 Q367H, Q367H,
532 7
375 9
376 9
530 10
524 10 V524G,
526 10 K526Q, K526E,
533 10 R533W, R533Q,
366 10 R366W, R366Q,
531 10
377 10
527 10
365 10 N365H,
522 11 Y522S,
364 11 F364L, F364L, F364L, F364S,
362 12 K362R, K362del,
378 12 A378T,
521 12
534 12
363 13 H363N,
523 13
380 14 R380S, R380S, R380G,
540 14
535 15
361 15