long QT syndrome 16

Long QT syndrome 16 is a disorder primarily affecting the heart’s electrical conduction system, characterized by abnormal cardiac repolarization and conduction delays. The condition is linked to pathogenic variants in the CALM3 gene, which plays a critical role in calcium signaling within cardiac cells. It is inherited in an autosomal dominant pattern, meaning that a single copy of the altered gene is sufficient to cause the condition. Precise prevalence estimates are not well established, and clinical findings suggest that severity can vary among affected individuals.

The clinical features of long QT syndrome 16 include a set of cardiac abnormalities that are consistently observed. Individuals with this condition exhibit T‐wave alternans, bradycardia, and second degree atrioventricular block. Congenital heart anomalies such as a perimembranous ventricular septal defect and a patent ductus arteriosus after birth at term are also reported, along with a prolonged QTc interval on electrocardiograms. Although these findings are characteristic, not all individuals experience every feature, and the severity of symptoms can vary considerably.

Long QT syndrome 16 is caused by pathogenic variants in the CALM3 gene. This gene encodes a protein integral to calcium signaling, which is essential for proper cardiac electrical function. The condition is inherited in an autosomal dominant manner, indicating that an affected individual has a 50% chance of passing the variant on to each child. Genetic counseling is recommended to help families understand the implications of this inheritance pattern and to facilitate informed decision-making.

Currently, management of long QT syndrome 16 focuses on supportive care and symptom management, as there are no FDA-approved treatments specifically for this condition. Treatment is tailored to the individual and often involves a multidisciplinary team that may include cardiologists and other specialists. Regular cardiac monitoring and interventions, when necessary, are important components of patient care. Patients should discuss treatment options with their healthcare team to determine which therapies may be appropriate for their specific situation, and genetic counseling can be beneficial for family planning.

The long-term outlook for individuals with long QT syndrome 16 varies depending on symptom severity, age at diagnosis, and access to specialized care. With current standards of care, many individuals experience improvements in quality of life and outcomes have improved as management strategies continue to evolve. It is important to recognize that the condition may progress, stabilize, or follow a variable course in different individuals. Families often find it helpful to connect with cardiology specialists and genetic counselors to discuss potential risks and ongoing care, and outcomes described in medical literature continue to evolve as standards of care improve.