Cardiac safety

QT-prolonging medicines

Several hundred medicines lengthen the heart's recovery time as a side effect. Most people absorb it without consequence — and the reason some do not is partly written in common variants that do nothing on their own.

What this drug connects to

The genes involved

NOS1AP

QT Interval and Drug-Induced Long QT →

A mechanism with population evidence behind it and no clinical test in front of it. Several hundred medicines prolong the QT interval, and most people absorb that without consequence because the heart has spare capacity to repolarise on time. Common QT variants appear to reduce that spare capacity: a risk score built from them was associated with drug-induced QT prolongation and with torsade de pointes (Strauss et al., Circulation 2017). No society recommends genotyping before prescribing, and the factors clinicians actually act on — potassium and magnesium levels, heart rate, kidney function, other QT-prolonging drugs — matter more. Useful as an explanation of why the same drug is uneventful in most people and not in everyone.

Strauss DG et al., Common Genetic Variant Risk Score Is Associated With Drug-Induced QT Prolongation and Torsade de Pointes Risk. Circulation 2017; CredibleMeds QT drug lists

Variants MyGeneLog™ reports for these genes

These are the positions in your own file that carry the genes above. Not every gene in a guideline is one we report — where that is the case the gene appears above without a variant here, and the note says so.

Platelet count

NOS1AP · rs6684278

Smoking cessation

NOS1AP · rs10918790

Smoking cessation

NOS1AP · rs4657158

Mean platelet volume during third trimester of pregnancy

NOS1AP · rs78344479

Educational attainment

NOS1AP · rs80159981

QT interval

NOS1AP · rs12029454

QT interval

NOS1AP · rs73017364

Mean spheric corpuscular volume

NOS1AP · rs12567315

QT interval

NOS1AP · rs6669543

QT interval

NOS1AP · rs16857031

QT interval

NOS1AP · rs17457880

Body mass index (change over time)

NOS1AP · rs347313

Granulocyte percentage of myeloid white cells

NOS1AP · rs6658646

Monocyte percentage of white cells

NOS1AP · rs6677530

Monocyte count

NOS1AP · rs60441301

FCGR3B protein levels

NOS1AP · rs10800384

FCRLB protein levels

NOS1AP · rs191648462

QT interval

NOS1AP · rs17460657

QT interval

NOS1AP · rs347272

QT interval

NOS1AP · rs164133

FCGR2A protein levels

NOS1AP · rs7539084

Low affinity immunoglobulin gamma Fc region receptor II-b levels

NOS1AP · rs189676321

monocyte (fraction, minimum, inv-norm transformed)

NOS1AP · rs10918705

FCGR3B protein levels

NOS1AP · rs114836703

FCGR2A protein levels

NOS1AP · rs560123160

FCGR2A protein levels

NOS1AP · rs146009967

Mean reticulocyte volume (UKB data field 30260)

NOS1AP · rs7536043

Questions about QT-prolonging medicines

What are QT-prolonging medicines?

QT-prolonging medicines are drugs — certain antiarrhythmics, antipsychotics, antibiotics and antiemetics — that lengthen the heart’s recovery time as a side effect. Most people absorb this without consequence, and the reason some do not is partly written in common variants that do nothing on their own.

Does the NOS1AP variant predict who is at risk from QT-prolonging medicines?

Partly, at a population level. A risk score built from common QT variants near NOS1AP was associated with drug-induced QT prolongation and with the dangerous arrhythmia torsade de pointes in one study — but this is population-level evidence, not a personal prediction, and no clinical test is used before prescribing.

Is genetic testing used to decide who can take QT-prolonging medicines?

No. No medical society recommends genotyping before prescribing a QT-prolonging drug. The factors clinicians actually check — potassium and magnesium levels, heart rate, kidney function, and other QT-prolonging drugs a person is taking — matter more.

Quoting this page

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QT-prolonging medicines. MyGeneLog™. https://www.mygenelog.com/drugs/qt-prolonging-medicines

This page is educational and contains no dosing information. Where a clinical guideline covers one of these gene-drug pairs it is written for prescribers and works through validated algorithms alongside clinical monitoring. Nothing here is a reason to start, stop, or change a medication — that conversation belongs with the clinician or pharmacist managing your treatment.