SCN5A Variant L1646Q Detail

We estimate the penetrance of LQTS for SCN5A L1646Q around 24% and the Brugada syndrome penetrance around 21%. SCN5A L1646Q was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. L1646Q is not present in gnomAD. L1646Q has been functionally characterized in 0 papers. This residue is located in a Mild_Hotspot region for Brugada syndrome and a Mild_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 (1 with LQTS). These data combined with observations of carriers lead us to estimate the LQTS penetrance for SCN5A L1646Q around 24% (1/10) and the Brugada syndrome penetrance around 21% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.998 22 29
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 12 1 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.

L1646Q 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
403 11
414 11 M414V,
1643 5 I1643L,
404 10 L404Q, L404V,
1778 8
1773 14
249 11 K249X,
1653 11
254 12
1771 10 I1771T,
1652 10 M1652R, M1652T,
1634 11 L1634P,
1777 11 V1777M, V1777L,
250 11
409 13 L409P, L409V,
1650 6 L1650F,
260 13
1641 10
258 15 V258A,
1639 13 G1639A,
246 15
1779 9 T1779M,
412 14 V412D,
1776 11
1787 12 S1787N,
1654 12
1648 8
415 15 A415T,
1649 6 A1649V,
1774 10 c.5321_5324dupACTT, N1774D,
1644 8 R1644H, R1644C, R1644L,
1640 10
256 8
399 15
405 13
1657 15
1781 13 E1781D, E1781G,
1789 12
255 11
1772 11 L1772V,
1645 5 T1645M,
251 12
410 9 A410V,
1780 13 E1780G,
1788 13 c.5361_5364delTGAG,
1770 14 I1770V,
1638 14 R1638X, R1638Q,
1651 9
259 14
1633 14
413 14 A413E, A413T,
1637 10
408 11
253 8
407 7
1783 15
1775 6 F1775V, p.F1775LfsX15,
1642 6 G1642E,
1790 15 p.D1790del, D1790N, D1790G,
406 12 N406K, N406S,
252 9
411 9 V411M,
1647 4
257 12
400 14 G400A, G400R, G400E,
1646 0
1782 11