SCN5A Variant L227Q Detail

We estimate the penetrance of LQTS for SCN5A L227Q around 8% and the Brugada syndrome penetrance around 18%. SCN5A L227Q was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. L227Q is not present in gnomAD. L227Q 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 (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 L227Q around 8% (0/10) and the Brugada syndrome penetrance around 18% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.939 18 6
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.

L227Q has 63 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 7 I848F,
223 8 V223L,
856 12 V856L,
842 15
240 10 V240M,
231 9 c.692_693delCA,
198 14
193 7 W193X, W193R,
195 12
926 15
237 14
228 6 K228R,
138 11 M138I,
925 12 I925F,
227 0 L227P,
137 14 I137V,
142 12
197 10
229 6
851 10 c.2550_2551dupGT, c.2552_2553dupGT, F851L, p.F851CfsX19,
221 12
196 7
852 7
854 13 c.2559delT,
222 13 R222L, R222Q, R222X,
224 6 L224F,
845 9 c.2533delG,
232 11 V232I, V232F,
244 13
191 13
849 8
226 4 A226V, A226G,
921 15
241 14
843 15 T843A,
930 15 c.2787+17_2787+18insACACACACACACACACACACACA, c.2788-6C>T,
144 12
855 12
239 13 I239V , I239V,
230 6 I230T, I230V, I230M,
199 12 S199T,
139 15 p.I137_C139dup,
148 13
841 14 p.N841TfsX2, N841K,
236 12
847 11
203 14
846 12 L846R,
192 11
168 14
233 11
194 12
141 10 I141N, I141V,
853 11
201 14
225 7 R225Q, R225W,
844 12 L844RfsX3,
850 12 V850M, c.2549_2550insTG,
243 12
200 10
145 11
140 14
220 14 T220I,