SCN5A Variant I1633M Detail

We estimate the penetrance of LQTS for SCN5A I1633M around 22% and the Brugada syndrome penetrance around 33%. SCN5A I1633M was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. I1633M is not present in gnomAD. I1633M has been functionally characterized in 0 papers. This residue is located in a 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 (3 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 I1633M around 22% (1/10) and the Brugada syndrome penetrance around 33% (3/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.853 44 27
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 11 1 3 - -
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.

I1633M has 56 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
1643 11 I1643L,
1627 12
1536 11
1538 9
1531 11
1635 7
1634 5 L1634P,
1543 14 V1543A, V1543L,
1534 12
1542 11
1650 15 L1650F,
260 11
1641 15
258 13 V258A,
1639 12 G1639A,
1630 6 I1630R, I1630V,
1532 11 V1532F, V1532I,
1644 11 R1644C, R1644H, R1644L,
1640 12
262 12 S262G,
256 10
261 14
1628 11
1589 14
1632 6 R1632L, R1632H, R1632C,
1530 15
1539 8 C1539Y, C1539F,
255 11
1645 15 T1645M,
1535 7
1537 13
1594 14 F1594S,
264 14
1638 11 R1638X, R1638Q,
1651 14
259 7
1633 0
1591 10 W1591X,
1595 13
1637 7
253 15
1636 5
263 11 V263I,
1629 10 R1629X, R1629G, R1629Q,
1533 13 T1533I,
1541 14
1642 14 G1642E,
1592 14
1540 13
1528 15
1631 5 G1631D,
1590 14
252 14
1647 11
257 13
1646 14