KCNH2 Variant E387Q Detail

We estimate the penetrance of LQTS for KCNH2 E387Q is 12%. We are unaware of any observations of this variant in individuals. E387Q is not present in gnomAD. E387Q has not been functionally characterized. This residue is located in a Mild_Hotspot region for LQT2. In silico predictions, functional data (if available), and location in structure are equivalent to observing 1 individuals with LQT2 and 9 unaffected individuals.These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 E387Q around 12% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-2.855 0.781 2 0.813 17
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: - 0 0 0 -
VARIANT FEATURES ALONE: - 10 9 1 -
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.

E387Q 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
387 0
386 4 P386X,
388 4
385 5
389 5
384 7
390 7
383 8
391 8 Q391X,
382 8 A382T,
392 8
381 9
393 9 P393L,
380 10 L380X,
394 10 R394C, R394H,
379 11 S379Y,
395 11
378 11
396 11
377 12
397 12 R397H, R397X,
376 13 Q376sp, Q376R,
398 13 W398X, W398L,
375 13
399 13
374 14
400 14 I400N,
373 14
401 14
372 15
402 15 H402R,