SCN5A Variant L136I Detail

We estimate the penetrance of LQTS for SCN5A L136I around 2% and the Brugada syndrome penetrance around 37%. SCN5A L136I was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. L136I is not present in gnomAD. L136I 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 L136I around 2% (0/10) and the Brugada syndrome penetrance around 37% (3/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.326 57 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 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.

L136I has 38 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
231 14 c.692_693delCA,
124 15 A124D,
131 9
164 12 F164L,
130 10
170 11 F170I,
228 13 K228R,
138 7 M138I,
171 10
143 11
137 5 I137V,
142 10
197 15
229 14
129 13
163 13 c.486delC,
169 14
127 11
232 13 V232I, V232F,
174 13 V174I,
133 6
132 5 c.393-5C>A,
134 7 N134S,
166 13 A166T,
144 13
172 15
139 5 p.I137_C139dup,
165 15
136 0 L136P,
168 11
175 14 K175N,
141 10 I141V, I141N,
135 5 M135V,
167 9
128 11 c.381dupT,
225 13 R225W, R225Q,
145 15
140 7