SCN5A Variant R121G Detail

We estimate the penetrance of LQTS for SCN5A R121G around 4% and the Brugada syndrome penetrance around 45%. SCN5A R121G was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. R121G is not present in gnomAD. R121G 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 (4 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 R121G around 4% (0/10) and the Brugada syndrome penetrance around 45% (4/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.897 65 1
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 11 0 4 - -
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.

R121G has 34 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
126 9 K126E,
175 11 K175N,
113 10 V113I, V113A,
129 12
188 14
178 5 A178G,
128 10 c.381dupT,
117 8
179 7 R179Q, R179X,
119 7 P119L, P119S,
177 6 L177P,
123 7 A123V, A123G,
121 0 R121Q, R121W,
127 11
124 6 A124D,
118 6
125 6 V125L,
181 11
176 9
172 14
174 9 V174I,
185 14 A185T, A185V,
115 6 S115G,
182 14 C182R, C182Y,
173 11
112 10 Y112C,
114 6
184 11 H184R,
170 14 F170I,
116 6
180 8 G180V,
120 6
183 14
122 5