SCN5A Variant I1643L Detail

We estimate the penetrance of LQTS for SCN5A I1643L around 11% and the Brugada syndrome penetrance around 14%. SCN5A I1643L was found in a total of 1 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. I1643L is present in 1 alleles in gnomAD. I1643L has been functionally characterized in 0 papers. This residue is located in a Mild_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 (1 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 I1643L around 11% (0/11) and the Brugada syndrome penetrance around 14% (1/11).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
-1.85 0.943 3.55 0.915 20 14
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
LITERATURE, COHORT, AND GNOMAD: - 1 1 0 0 -
VARIANT FEATURES ALONE: - 15 14 0 1 - -
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.

I1643L has 50 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
403 14
414 14 M414V,
1643 0 I1643L,
404 12 L404Q, L404V,
1778 12
249 11 K249X,
1635 14
254 10
1771 14 I1771T,
1652 14 M1652T, M1652R,
1634 9 L1634P,
250 10
1650 10 L1650F,
260 12
1641 8
258 12 V258A,
1639 9 G1639A,
1779 12 T1779M,
1787 14 S1787N,
1648 10
1649 10 A1649V,
1774 15 N1774D, c.5321_5324dupACTT,
1644 7 R1644L, R1644H, R1644C,
1640 6
256 7
248 15
1789 12
255 8
1645 6 T1645M,
251 9
410 13 A410V,
1788 15 c.5361_5364delTGAG,
1638 11 R1638Q, R1638X,
1651 12
259 11
1633 11
1637 6
408 13
253 7
1636 11
407 10
1775 11 p.F1775LfsX15, F1775V,
1642 4 G1642E,
1631 14 G1631D,
252 6
411 12 V411M,
1647 5
257 10
1646 5
1782 13