SCN5A Variant L754Q Detail

We estimate the penetrance of LQTS for SCN5A L754Q around 13% and the Brugada syndrome penetrance around 28%. SCN5A L754Q was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. L754Q is not present in gnomAD. L754Q 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 (0 with LQTS). These data combined with observations of carriers lead us to estimate the LQTS penetrance for SCN5A L754Q around 13% (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 0.873 36 14
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.

L754Q has 38 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
758 7 G758E,
811 11 R811H, R811G, c.2435_2436+3delTGGTAinsCGCCT,
733 11 F733L,
808 13 R808P, R808C, R808H,
746 13 E746K,
760 11 p.F760SfsX5,
759 10 I759V, c.2274delG, p.I759FfsX6,
792 10
755 5
791 15 L791F,
800 10 R800H, R800L, R800C,
754 0
726 13
797 12 G797V,
737 15
750 6 Q750R,
749 10
788 14 I788V,
798 14
793 10 L793F,
762 13
747 10 E747A,
734 13 M734V, c.2201dupT,
756 8
814 12 R814Q,
757 6
761 11
752 5 G752R,
751 5 V751I, V751F,
796 7
730 11 N730K,
789 13 V789A, V789I,
753 5
729 14 p.L729del,
795 10
748 11 M748I,
799 11
794 14