SCN5A Variant G999C Detail

We estimate the penetrance of LQTS for SCN5A G999C around 5% and the Brugada syndrome penetrance around 8%. SCN5A G999C was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. G999C is not present in gnomAD. G999C has been functionally characterized in 0 papers. This residue is located in a Non_Hotspot region for Brugada syndrome and a Non_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 G999C around 5% (0/10) and the Brugada syndrome penetrance around 8% (0/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.493 3 3
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: - 0 0 0 0 -
VARIANT FEATURES ALONE: - 15 15 0 0 - -
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.

G999C 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. 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
984 15
985 14
986 14 R986L, R986W, R986Q,
987 13
988 13 R988Q, R988W,
989 12
990 11
991 11 K991E, K991T,
992 10
993 9 A993T, A993S,
994 8 A994V, A994T,
995 8 L995F,
996 7 A996T,
997 5 A997S, A997D, A997T,
998 4
999 0 G999D,
1000 4 p.Gln1000del, Q1000L, Q1000X,
1001 5
1002 7 P1002S, c.3005-3012delCCAGCTGG,
1003 8
1004 8 C1004R,
1005 9 I1005V, I1005T,
1006 10 A1006S,
1007 11 T1007I, T1007N,
1008 11 P1008S,
1009 12
1010 13
1011 13 P1011L, P1011S,
1012 14
1013 14
1014 15 P1014S,