SCN5A Variant I1688M Detail

We estimate the penetrance of LQTS for SCN5A I1688M around 3% and the Brugada syndrome penetrance around 28%. SCN5A I1688M was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. I1688M is not present in gnomAD. I1688M 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 (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 I1688M around 3% (0/10) and the Brugada syndrome penetrance around 28% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.731 37 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: - 0 0 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.

I1688M has 62 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
333 13 c.998+1G>A, c.998+5G>A,
1702 11
1741 12 D1741Y, D1741N, D1741E,
1715 8
1687 4
1698 14 A1698T,
1675 14
1743 13 G1743E, G1743R,
334 15 c.999-424_1338+81del,
1711 14 c.5131delG,
332 15 A332T,
1707 13
1681 12 c.5040_5042delTTAinsC, Y1681F,
1694 8
1704 13 L1704H,
1706 11 Q1706H,
1695 10 Q1695X,
376 14 R376H, R376C,
1716 7 p.L1716SfsX71,
1714 12 D1714G,
1688 0
1684 5 W1684R,
1676 14 M1676T, M1676I,
1692 7
1744 13 S1744I,
1721 12
1742 14
1693 6
378 13
1699 10
331 15
1712 11 G1712C, G1712S,
379 10
1680 11 A1680T, A1680P,
1703 9
1719 6
1701 15 M1701I,
1690 7 D1690N, c.5068_5070delGA,
324 14
1227 15
1399 15
1713 14
383 12
1748 14 p.G1748del, G1748D,
1683 9
382 14
1718 10 S1718R,
1696 13
1689 5 D1689N,
1700 11
1717 11 L1717P,
1751 15
1682 8
1752 13
1686 6
1740 15 G1740R,
375 12
1691 8
380 14
1720 9 c.5157delC,
1679 11
1685 6