KCNQ1 Variant T309I

Summary of observed carriers, functional annotations, and structural context for KCNQ1 T309I. Data combine curated literature, international cohorts, and gnomAD observations.

Estimated LQT1 penetrance

56%

19/35 effective observations

Total carriers

25

11 LQT1 · 14 unaffected

Functional studies

0

Publications with functional data

T309I has not been reported in gnomAD. This residue resides in a Hotspot region for LQT1.

Variant features alone are equivalent to phenotyping 8 individuals with LQT1 and 2 unaffected individuals.

In silico predictors

Variant-level computational predictors.
PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density LQT1 (%)
-5.74 1.0 0 0.91 84

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 LQT1 Other Disease
33574382 2021 24 14 10 None
26118593 2015 1 None 1 None
Literature, cohort, and gnomAD – 25 14 11 –
Variant features alone – 15 2 8 –

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

Nearby variants

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

Previously observed variants near T309I.
Neighbour residue Distance (Å) Observed variants
312 10 T312del, T312I,
309 10 T309I, T309R,
314 10 G314S, G314D, G314C, G314del,
330 11
313 11
337 12
333 12
308 12 V308F,
311 12 T311A, T311I,
310 12 V310I,
329 13 A329T,
315 13 Y315C, Y315S, Y315N, Y315H, Y315F
316 13 G316E, G316R, G316R, G316V,
305 13 W305S, W305L, W305C, W305C, W305R, W305R,
326 13
334 13 V334A,
303 14 L303P,
279 14 F279I,
331 14
306 14 G306V, G306R, G306R,
319 14 V319L, V319L,
320 14 P320H, P320A, P320S,
275 14 F275del,
270 14 F270S,
336 15 A336S,
307 15 V307L, V307L,
327 15 T327A, T327S, T327S,
271 15
328 15 I328del,
325 15 G325R, G325R, G325E, G325W,