Timothy syndrome type 2

Timothy syndrome type 2 (TS2) is an extremely rare and severe multisystem disorder caused by gain-of-function mutations in the CACNA1C gene, which encodes the alpha-1C subunit of the L-type voltage-gated calcium channel (Cav1.2). Unlike classic Timothy syndrome (type 1), which is caused by a specific mutation in exon 8A, Timothy syndrome type 2 results from mutations in the alternatively spliced exon 8, which is more broadly expressed across tissues. This distinction means that TS2 can present with a broader and potentially more severe phenotypic spectrum. The condition primarily affects the heart, nervous system, and other organ systems. Cardiac manifestations include severe prolongation of the QT interval (long QT syndrome), life-threatening ventricular arrhythmias such as 2:1 atrioventricular block, ventricular tachycardia, and ventricular fibrillation, as well as structural heart defects in some cases. Neurological features may include intellectual disability, autism spectrum disorder, seizures, and developmental delays. Notably, Timothy syndrome type 2 may lack the syndactyly (webbing of fingers and toes) that is a hallmark of classic Timothy syndrome type 1, which can make clinical recognition more challenging. Treatment is primarily supportive and symptom-directed. Management of cardiac arrhythmias may include beta-blockers, sodium channel blockers such as mexiletine, and in some cases implantable cardioverter-defibrillators (ICDs). Due to the extreme rarity of the condition, there are no established disease-specific therapies, and management requires a multidisciplinary approach involving cardiology, neurology, and developmental specialists. The prognosis is guarded, as sudden cardiac death remains a significant risk, particularly in early life.

Common questions about Timothy syndrome type 2