KCNH2 Variant R273Q

Summary of observed carriers, functional annotations, and structural context for KCNH2 R273Q. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT2 penetrance

7%

0/17 effective observations

Total carriers

7

0 LQT2 · 5 unaffected

Functional studies

1

Publications with functional data

R273Q is present in 2 alleles in gnomAD. This residue resides in a Non_Hotspot region for LQT2.

We have tested the trafficking efficiency of this variant: 90% of WT with a standard error of 14%. 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.

Variant features alone are equivalent to phenotyping 0 individuals with LQT2 and 10 unaffected individuals.

In silico predictors

Variant-level computational predictors.
PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density LQT2 (%)
-1.578 0.962 -1 0.683 0

PROVEAN scores below -2 suggest deleterious impact. REVEL scores above 0.5–0.75 are often interpreted as likely pathogenic. PolyPhen-2 scores above 0.85 are typically pathogenic. BLAST-PSSM reflects evolutionary conservation; more negative values indicate rarer substitutions. Penetrance density summarises neighbouring residue risk (Kroncke et al. 2019).

Reported carrier data

Observed carriers by publication or cohort.
Source Year Carriers Unaffected LQT2 Other Disease
Italy Cohort 2020 5 5 0
17210839 1 0 SIDS
Literature, cohort, and gnomAD 7 5 0
Variant features alone 10 10 0

Totals may differ from individual publications due to duplicate patients removed during curation.

Functional data

Functional assay results from published electrophysiology studies. Steady state (S.S.) and peak tail current are relative % to wildtype (100% being no different from wildtype). V1/2 activation and inactivation are the voltages at which half of the maximal current is reached, in mV. Recovery from inactivation and deactivation time are ratios of characteristic time constants with wildtype. HM indicates homomeric channels, HT indicates heteromeric channels.

Homomeric channel data

Published electrophysiology measurements (homomeric).
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

Heteromeric channel data

Published electrophysiology measurements (heteromeric).
PubMed ID Cell Type S.S Peak (%WT) Peak Tail IKr (%WT) V1/2 Act. V1/2 Inact. Deactivation (%WT)
18222468 CHO 63 None None None

Nearby variants

Neighbouring residues within 15 Ångström provide structural context. Variants listed in the right-most column have been observed clinically or in gnomAD. Note that 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 15Å window.

Previously observed variants near R273Q.
Neighbour residue Distance (Å) Observed variants
273 0 R273Q, R273X,
272 4
274 4 E274X
271 5 R271L,
275 5 S275R, S275R, S275R,
270 7
276 7 C276X,
269 8
277 8
268 8 A268X,
278 8
267 9
279 9
266 10 S266G,
280 10
265 11
281 11 R281fsX, R281X,
264 11
282 11 A282X,
263 12
283 12
262 13 G262fsX, G262X,
284 13 S284X,
261 13 S261X,
285 13 A285fsX, A285V,
260 14 A260V,
286 14 D286X,
259 14 D259X, D259N,
287 14 D287fsX,
258 15 P258L,
288 15