The clinical manifestations of CACNA1C-related disorders include a spectrum of nonsyndromic and syndromic phenotypes, which generally correlate with the impact of the pathogenic variant on calcium current. Phenotypes can include nonsyndromic long QT syndrome (rate-corrected QT [QTc] interval >480 ms); nonsyndromic short QT syndrome (QTc <350 ms), with risk of sudden death; Brugada syndrome (ST segment elevation in right precordial leads [V1-V2]) with short QT interval; classic Timothy syndrome (prolonged QT interval, autism, and congenital heart defect) with or without unilateral or bilateral cutaneous syndactyly variably involving fingers two (index), three (middle), four (ring), and five (little) and bilateral cutaneous syndactyly of toes two and three; and CACNA1C-related neurodevelopmental disorder, in which the features tend to favor one or more of the following: developmental delay / intellectual disability, hypotonia, epilepsy, and/or ataxia.

Immunodeficiency-82 with systemic inflammation (IMD82) is a complex autosomal dominant immunologic disorder characterized by recurrent infections with various organisms, as well as noninfectious inflammation manifest as lymphocytic organ infiltration with gastritis, colitis, and lung, liver, CNS, or skin disease. One of the more common features is inflammation of the stomach and bowel. Most patients develop symptoms in infancy or early childhood; the severity is variable. There may be accompanying fever, elevated white blood cell count, decreased B cells, hypogammaglobulinemia, increased C-reactive protein (CRP; 123260), and a generalized hyperinflammatory state. Immunologic workup shows variable B- and T-cell abnormalities such as skewed subgroups. Patients have a propensity for the development of lymphoma, usually in adulthood. At the molecular level, the disorder results from a gain-of-function mutation that leads to constitutive and enhanced activation of the intracellular inflammatory signaling pathway. Treatment with SYK inhibitors rescued human cell abnormalities and resulted in clinical improvement in mice (Wang et al., 2021).