SCN5A Variant I848M Detail

We estimate the penetrance of LQTS for SCN5A I848M around 29% and the Brugada syndrome penetrance around 23%. SCN5A I848M was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. I848M is not present in gnomAD. I848M 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 (2 diagnosed with Brugada syndrome) and 5 individuals for LQTS (1 with LQTS). These data combined with observations of carriers lead us to estimate the LQTS penetrance for SCN5A I848M around 29% (1/10) and the Brugada syndrome penetrance around 23% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.909 27 36
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 12 1 2 - -
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.

I848M has 64 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 12 I891N, I891T,
888 11
848 0 I848F,
223 10 V223L,
856 13 V856L,
895 13 L895F,
839 14 L839P,
842 10
240 11 V240M,
231 11 c.692_693delCA,
1455 15
149 14
193 13 W193X, W193R,
926 11
228 10 K228R,
138 13 M138I,
925 12 I925F,
227 7 L227P,
143 15
887 14
234 14 P234S,
1451 15 V1451D, V1451L,
142 11
229 6
933 15
851 6 c.2552_2553dupGT, c.2550_2551dupGT, F851L, p.F851CfsX19,
196 14
852 6
854 10 c.2559delT,
224 10 L224F,
845 5 c.2533delG,
857 15 G857D,
232 11 V232I, V232F,
892 13 F892I,
849 5
226 7 A226V, A226G,
921 15
922 13 V922I,
235 14 c.703+1G>A, c.704-1G>C, G235R,
840 11
843 9 T843A,
930 11 c.2787+17_2787+18insACACACACACACACACACACACA, c.2788-6C>T,
144 13
855 11
239 12 I239V, I239V ,
230 6 I230M, I230V, I230T,
148 13
929 14
884 13
841 11 p.N841TfsX2, N841K,
236 12
847 4
146 13 V146A, V146M,
846 7 L846R,
233 9
838 15
141 11 I141N, I141V,
853 9
225 12 R225Q, R225W,
844 6 L844RfsX3,
850 7 c.2549_2550insTG, V850M,
243 12
145 10
931 14