SCN5A Variant A166T Detail

We estimate the penetrance of LQTS for SCN5A A166T around 0% and the Brugada syndrome penetrance around 1%. SCN5A A166T was found in a total of 70 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. A166T is present in 70 alleles in gnomAD. A166T has been functionally characterized in 1 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 (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 A166T around 0% (0/80) and the Brugada syndrome penetrance around 1% (1/80).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
-2.26 0.999 -0.59 0.801 11 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: - 70 70 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.

Functional Data

Peak and late/persistent current are relative to wildtype (100% being no different from wildtype). V0.5 act/inact are the voltages at which half of the maximal current is reached during an activation and inactivation protocol, each is in units of mV and relative to wildtype.
PubMed ID Year Cell Type Peak Current (%WT) V1/2 Act. (mV) V1/2 Inact. (mV) Late/Persistent Current (%WT)
32533946 2020 HEK 103 4.2 -8.5

A166T has 41 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
198 14
147 15
164 7 F164L,
209 15 N209T, N209S,
170 7 F170I,
171 9
143 14
137 11 I137V,
158 14 K158T,
197 14
163 5 c.486delC,
169 5
222 13 R222L, R222X, R222Q,
174 12 V174I,
133 13
157 15 T157I,
160 10 p.V160fs,
205 10 Y205X, c.612-2A>G,
206 14
166 0 A166T,
144 13
172 10
139 15 p.I137_C139dup,
165 4
204 10 c.611+1G>A, c.611+3_611+4dupAA, A204V, A204T,
162 8 Y162H, Y162C,
208 10 E208K,
136 13 L136P,
168 6
202 13 I202T,
175 14 K175N,
141 13 I141V, I141N,
167 4
161 10 E161Q, E161K,
201 10
225 13 R225Q, R225W,
159 12 Y159C, Y159X,
207 14
173 11
200 14
140 10