SCN5A Variant M203L Detail

We estimate the penetrance of LQTS for SCN5A M203L around 5% and the Brugada syndrome penetrance around 35%. SCN5A M203L was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. M203L is not present in gnomAD. M203L has been functionally characterized in 0 papers. This residue is located in a 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 (3 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 M203L around 5% (0/10) and the Brugada syndrome penetrance around 35% (3/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.774 50 2
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 0 3 - -
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.

M203L has 49 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 13 V856L,
859 13
198 11
164 15 F164L,
209 11 N209S, N209T,
195 10
227 14 L227P,
197 11
216 10 S216L, S216X,
221 7
196 10
169 13
189 14
852 15
222 8 R222X, R222Q, R222L,
224 9 L224F,
213 15
226 14 A226G, A226V,
205 9 c.612-2A>G, Y205X,
860 14 p.L860fsx89,
206 6
214 13
211 13
144 15
217 7
855 15
172 14
199 6 S199T,
148 15
165 12
210 14 I210T,
204 5 A204T, c.611+3_611+4dupAA, c.611+1G>A, A204V,
162 15 Y162C, Y162H,
203 0
208 10 E208K,
168 12
202 5 I202T,
194 15
161 13 E161K, E161Q,
201 7
219 10 c.656_657insATTCA, R219H, p.R219HfsX11, R219C,
225 11 R225W, R225Q,
218 5
207 7
212 13 L212P, L212Q,
215 11 p.L215CfsX10,
200 5
220 9 T220I,