SCN5A Variant Q270H Detail

We estimate the penetrance of LQTS for SCN5A Q270H around 26% and the Brugada syndrome penetrance around 27%. SCN5A Q270H was found in a total of 0 carriers in 0 papers and/or in gnomAD: 0 had Brugada syndrome, 0 had LQTS. Q270H is not present in gnomAD. Q270H 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 Q270H around 26% (1/10) and the Brugada syndrome penetrance around 27% (2/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density BrS (%) Penetrance Density LQT3 (%)
NA NA NA 0.917 35 33
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.

Q270H has 64 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 15
277 14
271 6 L271V,
266 6 L266H,
276 13 L276P, L276Q,
1544 10 T1544P,
270 0 Q270K,
1627 9
385 14 A385T,
1624 9 V1624I,
1552 14 Q1552R, Q1552L,
355 9 F355I, F355C,
1549 10
1538 15
1556 15
356 10 D356N,
1543 12 V1543L, V1543A,
1542 10
1557 13 I1557V,
361 11
343 15
365 14
1564 13
354 12
1546 9 M1546T,
1545 6
1630 15 I1630R, I1630V,
1626 10 R1626P, R1626C, R1626L, R1626H,
267 6
1550 10
1625 12
1560 12 L1560F,
262 12 S262G,
357 11
272 8
274 10 G274C,
362 14
261 15
273 6
1628 13
392 12
389 13 Y389H, Y389X,
269 4
1620 8 T1620M, T1620K,
275 10 N275K,
264 11
1548 7 E1548K, G1548K,
265 9 A265V,
1619 9 P1619Q, c.4856delC, P1619L,
358 10
1551 12 D1551Y, D1551N,
263 11 V263I,
359 13 p.A359PfsX12, A359T,
1547 10 V1547L,
1563 15
1541 11
381 15 c.1141-3C>A, c.1140+1G>A,
1617 15 p.F1617del,
268 6 G268S,
1622 11
1618 12
1621 11
1561 14
1623 5 c.4867delC, R1623X, R1623Q, R1623L,