SCN5A Variant L218I Detail

We estimate the penetrance of LQTS for SCN5A L218I around 6% and the Brugada syndrome penetrance around 19%. SCN5A L218I was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. L218I is not present in gnomAD. L218I 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 L218I around 6% (0/10) and the Brugada syndrome penetrance around 19% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.803 21 4
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.

L218I has 42 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
223 11 V223L,
856 12 V856L,
859 10
209 9 N209S, N209T,
195 15
863 15
158 14 K158T,
216 6 S216L, S216X,
221 7
196 14
222 8 R222X, R222L, R222Q,
224 12 L224F,
213 10
857 14 G857D,
205 10 Y205X, c.612-2A>G,
860 11 p.L860fsx89,
206 6
214 9
858 15 M858L,
211 10
217 4
855 14
199 11 S199T,
148 14
165 13
210 11 I210T,
204 7 A204T, c.611+3_611+4dupAA, A204V, c.611+1G>A,
162 14 Y162C, Y162H,
203 5
208 10 E208K,
168 15
202 9 I202T,
161 12 E161K, E161Q,
201 11
219 6 p.R219HfsX11, R219H, c.656_657insATTCA, R219C,
225 14 R225Q, R225W,
218 0
207 5
212 9 L212Q, L212P,
215 7 p.L215CfsX10,
200 9
220 7 T220I,