KCNH2 Variant K344N Detail

We estimate the penetrance of LQTS for KCNH2 K344N is 7%. We are unaware of any observations of this variant in individuals. K344N is not present in gnomAD. K344N has not been functionally characterized. 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 K344N around 7% (0/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
0.035 0.11 1 0.412 1
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 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.

K344N 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
344 0
343 4 L343fsX,
345 4 G345S,
342 5 D342X, D342A, D342V,
346 5 D346E, D346N, D346Y, D346E,
341 7
347 7 P347S,
340 8 F340L, F340L, F340L,
348 8
339 8
349 8
338 9
350 9
337 10 T337X, T337S, T337S,
351 10 S351L,
336 11
352 11
335 11 Q335X,
353 11 T353S, T353S,
334 12 P334L,
354 12
333 13
355 13 D355G,
332 13
356 13 R356H, R356C,
331 14 S331T, S331N,
357 14 E357D, E357D,
330 14 I330V,
358 14
329 15
359 15 I359V,