KCNH2 Variant G314S Detail

We estimate the penetrance of LQTS for KCNH2 G314S is 7%. This variant was found in a total of 1 carriers in 0 papers or gnomAD, 0 had LQTS. G314S is present in 1 alleles in gnomAD. G314S has been functionally characterized in 1 papers. This residue is located in a Non_Hotspot region for LQT2. In silico predictions, functional data (if available), and location in structure are equivalent to observing 0 individuals with LQT2 and 10 unaffected individuals.These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 G314S around 7% (0/11).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-0.081 0.001 3 0.523 6
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 LQT2 Other Disease
LITERATURE, COHORT, AND GNOMAD: - 1 1 0 -
VARIANT FEATURES ALONE: - 10 10 0 -
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

Steady state (S.S.) and peak tail current are relative % to wildtype (100% being no different from wildtype). V0.5 act/inact are the voltages at which half of the maximal current is reached during an activation and inactivation protocol, each is 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 S.S Peak (%WT) Peak Tail IKr (%WT) V1/2 Act. V1/2 Inact. Recov. Inact. Deactivation (%WT)
31493597 HEK293 100 100 0.0 5.5 None None

Functional Data Heterozygously Collected

Functional parameters are the same as defined above.

PubMed ID Cell Type S.S Peak (%WT) Peak Tail IKr (%WT) V1/2 Act. V1/2 Inact. Deactivation (%WT)
31493597 HEK293 100 100 None None None

G314S 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 since the functional KV11.1 channel (protein product of KCNH2/hERG) 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
314 0 G314S,
313 4
315 4
312 5 R312Del, R312C, R312H,
316 5
311 7 L311R,
317 7 N317S,
310 8 P310L, P310X,
318 8
309 8 H309Q, H309Y, H309Q,
319 8 T319T,
308 9 M308I, M308V, M308I, M308T, M308R, M308I,
320 9 S320L, S320W, S320X,
307 10 A307P,
321 10 D321Y,
306 11 G306W,
322 11
305 11
323 11 D323E, D323N, D323E,
304 12 S304R, S304R, S304R,
324 12 L324L,
303 13
325 13 V325M,
302 13 H302X, H302H, H302fsX,
326 13 R326fsX, R326C, R326H,
301 14
327 14 Y327H,
300 14
328 14 R328fsX, R328C, R328H,
299 15
329 15