KCNH2 Variant S1040G Detail

We estimate the penetrance of LQTS for KCNH2 S1040G is 5%. This variant was found in a total of 5 carriers in 1 papers or gnomAD (version 4), 0 had LQTS. S1040G is present in 5 alleles in gnomAD. We have tested the trafficking efficiency of this variant, 117% of WT with a standard error of 5%; in our analysis we used SE < 20% as 'high quality'. Approximately below 50% of WT is considered PS3 moderate and below 30% is PS3 strong. S1040G 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 S1040G around 5% (0/15).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-2.348 0.0 -1 0.479 8
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
17210839 1 0 SIDS
LITERATURE, COHORT, AND GNOMAD: - 5 0 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)
18222468 CHO None None 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)
18222468 CHO 100 100 None None None

S1040G 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
1040 0
1039 4 E1039X,
1041 4
1038 5 V1038L, V1038L, V1038fsX, V1038M, V1038X,
1042 5
1037 7 D1037E, D1037E, D1037N, D1037X, D1037fsX,
1043 7 D1043G,
1036 8 G1036X, G1036Del, G1036fsX, G1036D,
1044 8
1035 8 R1035X, R1035fsX, R1035W, R1035Q,
1045 8 L1045F,
1034 9 P1034fsX, P1034X,
1046 9 Q1046X,
1033 10 R1033fsX, R1033W, R1033Q, R1033X,
1047 10 R1047L, R1047C, R1047H,
1032 11 R1032fsX, R1032X, R1032W, R1032Q, R1032P,
1048 11
1031 11 G1031fsX, G1031C, G1031X,
1049 11
1030 12 P1030X, P1030L,
1050 12
1029 13 S1029fsX,
1051 13
1028 13 S1028Del,
1052 13
1027 14 L1027I,
1053 14 E1053fsX, E1053X,
1026 14 P1026R,
1054 14 T1054fsX,
1025 15
1055 15 R1055Q, R1055W,