SCN5A Variant T423S Detail

We estimate the penetrance of LQTS for SCN5A T423S around 18% and the Brugada syndrome penetrance around 10%. SCN5A T423S was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. T423S is not present in gnomAD. T423S has been functionally characterized in 0 papers. This residue is located in a Non_Hotspot region for Brugada syndrome and a Mild_Hotspot region for LQTS. In silico predictions, functional data (if available), and location in structure are equivalent to phenotyping 10 individuals for Brugada syndrome (0 diagnosed with Brugada syndrome) and 5 individuals for LQTS (0 with LQTS). These data combined with observations of carriers lead us to estimate the LQTS penetrance for SCN5A T423S around 18% (0/10) and the Brugada syndrome penetrance around 10% (0/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.702 4 22
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 BrS/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 LQT3 BrS1 Other 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.

T423S has 24 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. 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
937 14
240 13 V240M,
418 9 E418K,
237 9
234 14 P234S,
417 10
245 14 Q245K,
415 12 A415T,
940 13 S940N,
420 6
241 11
235 10 c.703+1G>A, c.704-1G>C, G235R,
419 6 Q419X,
423 0
837 14
239 12 I239V , I239V,
242 12 A242D,
416 10 Y416C,
841 14 N841K, p.N841TfsX2,
236 12
238 7
838 13
422 4
421 7