KCNQ1 Variant R360G Detail

We estimate the penetrance of LQTS for KCNQ1 R360G is 81%. This variant was found in a total of 4 carriers in 4 papers or gnomAD, 4 had LQTS. R360G is not present in gnomAD. R360G 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 7 individuals with LQT1 and 3 unaffected individuals. These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 R360G around 81% (11/14).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-6.56 0.989 -3 0.843 82
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
21131640 2011 1 None 1 None
19808498 2009 1 None 1 None
19490272 2009 3 None 3 None
17470695 2007 3 None 3 None
LITERATURE, COHORT, AND GNOMAD: - 4 0 4
VARIANT FEATURES ALONE: - 10 3 7 -
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)
19808498 CHO 20 None 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)
19808498 CHO None None None

R360G has 14 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
538 11
537 11
539 12 R539W, R539L, R539Q,
531 13
360 13 R360ins, R360G, R360M,
357 14 Q357H, Q357H,
536 14
353 14 L353P,
356 14
535 14
541 15 V541I,
540 15
534 15
532 15