SCN5A Variant M858T Detail

We estimate the penetrance of LQTS for SCN5A M858T around 8% and the Brugada syndrome penetrance around 17%. SCN5A M858T was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. M858T is not present in gnomAD. M858T has been functionally characterized in 0 papers. This residue is located in a Mild_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 (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 M858T around 8% (0/10) and the Brugada syndrome penetrance around 17% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.953 16 6
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 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.

M858T has 63 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
891 11 I891T, I891N,
880 10
888 11
154 12 P154L,
223 10 V223L,
856 7 V856L,
890 10 I890T,
919 13
862 6
867 14 E867X, E867Q, E867K,
859 5
153 13
149 9
147 13
863 10
887 6
156 13 W156X, W156R,
864 11
886 10 H886Q, H886P,
216 12 S216L, S216X,
851 10 F851L, c.2552_2553dupGT, c.2550_2551dupGT, p.F851CfsX19,
221 12
909 15
852 11
854 6 c.2559delT,
222 12 R222X, R222Q, R222L,
224 14 L224F,
876 14
857 5 G857D,
150 12
902 14
882 7
881 6
226 15 A226G, A226V,
860 8 p.L860fsx89,
889 12
858 0 M858L,
144 13
217 13
918 13
855 5
865 10
148 9
884 7
906 13
866 12 S866L, S866P,
910 14 S910L,
885 11
146 14 V146A, V146M,
152 8 D152N,
853 11
219 10 c.656_657insATTCA, R219H, p.R219HfsX11, R219C,
877 14
151 8
879 14 W879R,
218 15
883 7
915 13 C915R,
850 12 V850M, c.2549_2550insTG,
914 14
145 12
861 8 p.F861WfsX90, c.2582_2583delTT,
220 9 T220I,