SCN5A Variant N927K Detail

We estimate the penetrance of LQTS for SCN5A N927K around 7% and the Brugada syndrome penetrance around 24%. SCN5A N927K was found in a total of 1 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. N927K is present in 1 alleles in gnomAD. N927K has been functionally characterized in 2 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 (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 N927K around 7% (0/11) and the Brugada syndrome penetrance around 24% (2/11).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
-5.31 0.062 0.07 0.673 48 5
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: - 1 1 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.

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)
17928536 2007 HEK 100 -6.8 -5.6
18690024 2007 HEK 172 -7.1

N927K has 74 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
891 11 I891N, I891T,
890 14 I890T,
919 12
896 7 C896S,
404 13 L404Q, L404V,
937 15
895 6 L895F,
1417 15
842 13
894 8 I894M,
247 13 V247L,
1455 14
254 14
372 12
401 13 S401P,
926 4
371 12 Q371E,
250 13
409 10 L409P, L409V,
928 4 L928P,
925 8 I925F,
366 12
934 11
1458 12 S1458Y,
933 10
246 13
935 10 L935P,
412 11 V412D,
897 7 G897R, G897E,
924 7 V924I,
927 0 N927S, N927K,
1466 15 c.4396_4397insG,
369 12 M369K,
845 14 c.2533delG,
1418 12
892 11 F892I,
373 15
1768 14 I1768V,
849 11
898 11
893 12 R893C, R893H,
921 11
922 8 V922I,
405 9
1462 14
920 11
843 14 T843A,
900 15
930 7 c.2788-6C>T, c.2787+17_2787+18insACACACACACACACACACACACA,
1459 10 c.4376_4379delTCTT,
918 14
1454 13
410 14 A410V,
242 15 A242D,
929 7
413 14 A413E, A413T,
408 9
847 14
407 14
846 10 L846R,
367 15 R367H, R367C, R367L,
936 13
1416 15 A1416G, c.4245+1G>C, A1416E, c.4245+2T>A, c.4245+1G>A,
853 12
370 9 T370M,
923 5
406 12 N406K, N406S,
899 10
850 12 V850M, c.2549_2550insTG,
411 14 V411M,
243 12
932 6
931 5
1463 12 N1463Y,