SCN5A Variant M138L Detail

We estimate the penetrance of LQTS for SCN5A M138L around 4% and the Brugada syndrome penetrance around 20%. SCN5A M138L was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. M138L is not present in gnomAD. M138L 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 (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 M138L around 4% (0/10) and the Brugada syndrome penetrance around 20% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.874 21 0
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.

M138L has 51 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
848 13 I848F,
223 14 V223L,
231 8 c.692_693delCA,
131 11
193 13 W193X, W193R,
164 12 F164L,
130 13
170 15 F170I,
228 7 K228R,
138 0 M138I,
227 11 L227P,
171 10
143 9
137 5 I137V,
234 14 P234S,
142 6
197 11
229 6
129 14
851 15 c.2552_2553dupGT, c.2550_2551dupGT, F851L, p.F851CfsX19,
196 13
224 14 L224F,
845 15 c.2533delG,
232 7 V232I, V232F,
133 9
132 11 c.393-5C>A,
134 7 N134S,
226 9 A226V, A226G,
144 10
172 15
230 10 I230M, I230V, I230T,
139 5 p.I137_C139dup,
148 15
165 15
236 14
146 13 V146A, V146M,
136 7 L136P,
168 10
175 13 K175N,
233 11
194 14
141 5 I141N, I141V,
135 7 M135V,
167 11
128 13 c.381dupT,
201 14
225 8 R225Q, R225W,
844 14 L844RfsX3,
200 14
145 10
140 7