KCNQ1 Variant S373P Detail

We estimate the penetrance of LQTS for KCNQ1 S373P is 49%. This variant was found in a total of 2 carriers in 6 papers or gnomAD, 1 had LQTS. S373P is not present in gnomAD. S373P has been functionally characterized in 1 papers. This residue is located in a Hotspot region for LQT1. In silico predictions, functional data (if available), and location in structure are equivalent to observing 4 individuals with LQT1 and 6 unaffected individuals. These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 S373P around 49% (5/12).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-2.82 0.996 2 0.764 53
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
32893267 2020 1 None 1 None
19490272 2009 6 None 6 None
17470695 2007 7 None 7 None
17192539 2006 1 None 1 None
12566525 2003 1 None 1 None
10220144 1999 7 1 1 None
LITERATURE, COHORT, AND GNOMAD: - 2 1 1
VARIANT FEATURES ALONE: - 10 6 4 -
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.

Functional Data Homozygously Collected

Peak current is relative to wildtype (100% being no different from wildtype). V0.5 activation is the voltages at which half of the maximal current is reached during an activation in units of mV and relative to wildtype. Recovery from inactivation (Rec. inact.) and deactivation time (Deactivation) are the ratio of characteristic time constants with wildtype (unitless).

PubMed ID Cell Type Peak Current IKs (%WT) V1/2 Act. Activation time (%WT) Deactivation time (%WT)
16556865 CHO 5 37.9 None None

Functional Data Heterozygously Collected

Functional parameters are the same as defined above.

PubMed ID Cell Type Peak Current IKs (%WT) V1/2 Act. Activation time (%WT) Deactivation time (%WT)
16556865 CHO None None None

S373P has 34 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
373 0 S373P,
372 4
374 5 L374H, L374F,
376 5
370 5 A370V,
371 5 A371T,
525 5 A525T, A525V,
377 6
375 6
369 7
528 8
529 8
522 8 Y522S,
524 8 V524G,
378 9 A378T,
521 9
380 9 R380S, R380S, R380G,
368 10
526 10 K526Q, K526E,
523 11
367 11 Q367H, Q367H,
527 11
532 12
379 12 W379R, W379R, W379C, W379C, W379G,
381 12 C381Y,
530 12
518 12 R518Q, R518G,
520 13 M520R,
531 14
533 14 R533W, R533Q,
517 14 I517T,
519 14 R519H, R519C,
365 14 N365H,
366 15 R366W, R366Q,