KCNH2 Variant T353A Detail

We estimate the penetrance of LQTS for KCNH2 T353A is 7%. We are unaware of any observations of this variant in individuals. T353A is not present in gnomAD. T353A 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 T353A around 7% (0/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-1.848 0.0 1 0.524 0
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
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.

T353A 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
353 0 T353S, T353S,
352 4
354 4
351 5 S351L,
355 5 D355G,
350 7
356 7 R356C, R356H,
349 8
357 8 E357D, E357D,
348 8
358 8
347 9 P347S,
359 9 I359V,
346 10 D346Y, D346N, D346E, D346E,
360 10
345 11 G345S,
361 11
344 11
362 11
343 12 L343fsX,
363 12 I363X,
342 13 D342V, D342A, D342X,
364 13 K364X,
341 13
365 13 E365G,
340 14 F340L, F340L, F340L,
366 14 R366Q, R366X,
339 14
367 14 T367S, T367S,
338 15
368 15 H368Y,