cacna1c-related disorders cacna1c-related disorders cacna1c-related disorders are a group of rare diseases caused by variants in the cacna1c gene, which encodes a subunit of the l-type voltage-dependent calcium channel. genomic sequencing has linked a number of heterogenous phenotypes to pathogenic variants in the cacna1c gene: timothy syndrome, which may or may not occur with syndactyly short qt syndrome or brugada syndrome long qt syndrome or other arrhythmia without additional symptoms. cacna1c-related disorders are inherited in an autosomal dominant manner. symptoms of cacna1c-related disorders are primarily neurological and may include developmental delay, autism or autistic features, and seizures. facial dysmorphism may also be present.