SCN5A Variant I137T Detail

We estimate the penetrance of LQTS for SCN5A I137T around 4% and the Brugada syndrome penetrance around 20%. SCN5A I137T was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. I137T is not present in gnomAD. I137T 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 (2 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 I137T around 4% (0/10) and the Brugada syndrome penetrance around 20% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.957 22 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 13 0 2 - -
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.

I137T has 50 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 11 c.692_693delCA,
198 13
124 14 A124D,
131 10
193 15 W193X, W193R,
164 10 F164L,
130 11
170 10 F170I,
228 9 K228R,
138 5 M138I,
227 14 L227P,
171 6
143 10
137 0 I137V,
142 9
197 10
229 11
129 12
163 12 c.486delC,
196 14
169 11
222 15 R222Q, R222L, R222X,
127 12
232 11 V232I, V232F,
174 11 V174I,
133 6
132 9 c.393-5C>A,
160 15 p.V160fs,
134 6 N134S,
226 12 A226V, A226G,
166 11 A166T,
144 11
172 11
230 14 I230M, I230V, I230T,
139 6 p.I137_C139dup,
165 12
136 5 L136P,
168 7
175 10 K175N,
194 13
141 6 I141N, I141V,
135 8 M135V,
167 7
128 10 c.381dupT,
201 12
225 8 R225Q, R225W,
173 13
200 14
140 5
145 13