SCN5A Variant M923L Detail

We estimate the penetrance of LQTS for SCN5A M923L around 4% and the Brugada syndrome penetrance around 13%. SCN5A M923L was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. M923L is not present in gnomAD. M923L 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 M923L around 4% (0/10) and the Brugada syndrome penetrance around 13% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.607 12 2
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.

M923L has 70 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
364 14
891 9 I891T, I891N,
890 12 I890T,
901 14 S901L, E901K,
919 8
363 12
896 9 C896S,
404 13 L404Q, L404V,
895 7 L895F,
894 6 I894M,
247 14 V247L,
254 13
372 9
401 13 S401P,
926 6
371 12 Q371E,
250 14
409 14 L409P, L409V,
928 6 L928P,
925 8 I925F,
904 14 W904X,
366 9
365 14
933 14
246 15
412 15 V412D,
897 6 G897R, G897E,
924 5 V924I,
927 5 N927S, N927K,
854 14 c.2559delT,
369 11 M369K,
1418 13
902 11
892 11 F892I,
373 13
849 12
888 15
898 10
893 10 R893C, R893H,
921 7
922 5 V922I,
405 11
362 14
261 15
920 6
889 15
900 11
930 10 c.2787+17_2787+18insACACACACACACACACACACACA, c.2788-6C>T,
1459 14 c.4376_4379delTCTT,
918 10
917 11 L917R, L917V,
916 11
929 9
906 15
408 12
846 12 L846R,
903 11 p.M903CfsX29,
367 11 R367C, R367L, R367H,
853 10
370 8 T370M,
923 0
915 13 C915R,
406 15 N406K, N406S,
368 14
899 6
850 12 c.2549_2550insTG, V850M,
243 15
932 11
257 14
931 10