SCN5A Variant M1676T Detail

We estimate the penetrance of LQTS for SCN5A M1676T around 4% and the Brugada syndrome penetrance around 9%. SCN5A M1676T was found in a total of 1 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. M1676T is present in 1 alleles in gnomAD. M1676T has been functionally characterized in 0 papers. This residue is located in a Non_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 (0 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 M1676T around 4% (0/11) and the Brugada syndrome penetrance around 9% (0/11).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
-5.75 0.999 -1.27 0.951 4 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: - 1 1 0 0 -
VARIANT FEATURES ALONE: - 15 15 0 0 - -
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.

M1676T has 67 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
1702 12
1741 15 D1741Y, D1741E, D1741N,
1304 10 T1304M,
1698 9 A1698T,
1220 13 G1220E,
1673 5
1675 4
1743 14 G1743R, G1743E,
1707 14
1681 10 c.5040_5042delTTAinsC, Y1681F,
1694 6
1704 11 L1704H,
1226 5
1747 13 V1747M,
1695 7 Q1695X,
1716 14 p.L1716SfsX71,
1688 14
1669 10
1671 10
1221 13 A1221V,
1668 12 M1668T,
1676 0 M1676T, M1676I,
1692 13
1744 13 S1744I,
1219 13 S1219N,
1672 5 S1672Y,
1693 9
1699 9
1239 14 L1239P,
1665 15
1305 14
1680 7 A1680P, A1680T,
1703 11
1235 15
1302 14 p.L1302Vfs18,
1701 10 M1701I,
1307 13
1228 11 Y1228F, Y1228H, Y1228C,
1690 15 c.5068_5070delGA, D1690N,
1678 7 N1678S,
1223 8 c.3667delG,
1755 14
1697 8
1222 10 p.L1222LfsX7, L1222R,
1227 8
1300 13
1674 8 F1674V,
1229 12
1748 14 p.G1748del, G1748D,
1301 10
1696 7
1705 15
1700 7
1751 11
1677 5
1682 11
1752 14
1224 11
1670 10
1740 14 G1740R,
1225 8 E1225K, G1225K,
1691 14
1720 13 c.5157delC,
1679 7
1667 14 V1667I,
1303 13 R1303Q, R1303W,
1666 15