SCN5A Variant M273L Detail

We estimate the penetrance of LQTS for SCN5A M273L around 16% and the Brugada syndrome penetrance around 24%. SCN5A M273L was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. M273L is not present in gnomAD. M273L 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 M273L around 16% (0/10) and the Brugada syndrome penetrance around 24% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.863 29 19
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.

M273L has 57 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
364 14
277 9
271 8 L271V,
266 10 L266H,
276 9 L276P, L276Q,
1544 14 T1544P,
348 15 P348A,
270 6 Q270K,
360 13
1627 14
385 13 A385T,
1624 14 V1624I,
1552 11 Q1552R, Q1552L,
355 8 F355C, F355I,
1549 7
278 11 H278R, H278D,
1556 14
356 6 D356N,
1557 12 I1557V,
361 10
343 9
365 15
384 13 S384T,
354 9
1546 12 M1546T,
1545 11
267 11
1550 5
1560 13 L1560F,
357 8
272 7
274 5 G274C,
273 0
1553 13 S1553R,
392 14
389 13 Y389H, Y389X,
269 5
1620 12 T1620M, T1620K,
345 14
275 7 N275K,
347 13
1548 7 G1548K, E1548K,
351 15 G351S, G351D, G351C, G351V,
265 11 A265V,
1619 12 P1619Q, c.4856delC, P1619L,
358 11
342 15
1551 8 D1551N, D1551Y,
346 15 E346G, E346K, E346X, E346D,
359 13 p.A359PfsX12, A359T,
1547 11 V1547L,
1554 15
344 13 A344S,
381 13 c.1140+1G>A, c.1141-3C>A,
268 8 G268S,
353 13 T353I,
1623 10 R1623Q, R1623L, R1623X, c.4867delC,