SCN5A Variant I768N Detail

We estimate the penetrance of LQTS for SCN5A I768N around 21% and the Brugada syndrome penetrance around 30%. SCN5A I768N was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. I768N is not present in gnomAD. I768N 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 I768N around 21% (1/10) and the Brugada syndrome penetrance around 30% (3/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.839 41 25
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.

I768N has 40 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
719 14
710 10
766 8
758 14 G758E,
715 15 M715T, M715I,
713 13
762 10
774 10 Y774C, Y774D, p.Y774TfsX28, c.2320delT,
784 14 F784L,
763 10 E763D, E763K,
778 12
767 6
772 7 D772N,
770 6
781 15 W781X,
775 10
771 6 L771V,
720 15
785 10 D785N,
783 11 I783T,
769 5
789 11 V789A, V789I,
773 6 P773S,
760 13 p.F760SfsX5,
714 11 V714A, V714D,
780 13
776 5 p.Y776del,
768 0
788 14 I788V,
765 5
786 9
759 15 c.2274delG, I759V, p.I759FfsX6,
761 10
711 12
787 13
779 12 Q779X, Q779K,
764 6 M764K, M764R,
777 7 F777L,
782 8 N782T,
790 13