Short QT syndrome is a genetic disorder that causes sudden cardiac death at a young age. mutation of SLC4A3 Genes that regulate bicarbonate and chloride exchange were recently reported as a potential cause. An international research team, including a group from Germany’s Ruhr University Bochum, investigated this possibility.
Researchers have discovered how different variants of the gene affect heart muscle cells. Specifically, the pH level increased and the flow of ion channels changed. This insight could help provide better personal care to people suffering from the disease. This study was published in the European Heart Journal on March 5, 2026.
arrhythmia
To maintain blood flow, the heart’s muscle cells must contract and relax in a coordinated manner. This process of contraction and relaxation is electrically controlled by controlling the flow of ions into and out of the cell through channels in the cell membrane. This is impaired in cases of short QT syndrome (SQTS). One result of this is that the time between contraction and relaxation of heart muscle cells, known as the QT interval or repolarization time, is shortened, thereby disrupting the heart’s rhythm.
The mechanisms underlying shortened action potential duration, shortened QT interval, and heart rhythm disturbances in SLC4A3 gene mutation carriers have been unclear until now. ”
Dr. Ibrahim El Batraoui, Ruhr University Bochum Cell and Translational Physiology Research Group Leader
To gain further insight, the research team examined two variants in the SCL4A3 gene that cause familial SQTS.
The study focused on two previously undescribed variants of the SLC4A3 gene, p.Arg370Cys and p.Lys531Thr. The research team generated human cardiomyocytes from induced pluripotent stem cells from families carrying this gene and corrected the mutations using CRISPR/Cas 9 to generate genetically identical cell lines. Additionally, the described mutations were inserted into human embryonic kidney cells (HEK cells). Various testing procedures were carried out to find out how mutations change cells. Patch clamp, Ca2+ transient imaging, single cell contraction, intracellular pH measurements, protein structure analysis, immunostaining, and optical mapping analysis were used in the organoid model.
It all starts with a change in pH
Cells with the mutated gene had significantly shorter action potential durations and higher rates of arrhythmic events. The inflow and outflow of ion channels changed. Cells showed a decrease in L-type calcium current (ICa-L) and a significant increase in sodium-calcium exchanger current (INCX). The intracellular pH increased considerably. The research team used ammonium chloride (NH4Cl) to induce this increase in pH levels compared to wild-type heart cells. In wild-type cells, this treatment shortened action potential duration, increased INCX, and decreased ICA-L. “We think this all starts with an increase in intracellular pH,” El-Batrawy says.
Two antiarrhythmic drugs, quinidine and sotalol, increased action potential duration and decreased arrhythmia frequency in mutant cells. “This information is very important for individualized treatment of SQTS patients with SLC4A3 mutations,” El-Batrawy says.
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Reference magazines:
Meng, Z. others (2026). SLC4A3-associated short QT syndrome evaluated in human induced pluripotent stem cell-derived cardiomyocytes: mechanisms of ventricular arrhythmia and sudden cardiac death. Science progresses. DOI: 110.1093/eurheartj/ehag068. https://academic.oup.com/eurheartj/advance-article-abstract/doi/10.1093/eurheartj/ehag068/8505953.
