Absence of familial adult myoclonic epilepsy‐associated intronic repeat expansions in SAMD12 , STARD7 , and MARCHF6 genes in juvenile myoclonic epilepsy with tremor

Abstract We investigated whether intronic repeat expansions in the SAMD12 , STARD7 , and MARCHF6 genes are present in individuals with juvenile myoclonic epilepsy (JME) and tremor. Given that tremor is a shared feature with familial adult myoclonic epilepsy (FAME), we hypothesized that this phenotype may reflect a common genetic basis involving FAME‐associated pentanucleotide repeat expansions. The study included 31 individuals with JME and tremor (17/31 [54.8%] females, mean age at genetic testing = 34.4 ± 13.8 years) and 100 age‐ and sex‐matched healthy controls. Genomic DNA was analyzed using repeat‐primed polymerase chain reaction and fragment analysis to detect intronic TTTCA repeat expansions in the three established FAME‐associated genes. No pathogenic repeat expansions were identified in SAMD12 , STARD7 , or MARCHF6 among individuals with JME and tremor. The frequency of intronic pentanucleotide repeat expansions did not differ between cases and controls. This is a comprehensive analysis assessing three FAME‐associated repeat‐expansion loci in a clinically well‐characterized cohort of individuals with JME and tremor. Our findings do not support a major contribution of these FAME‐associated loci to tremor in this cohort, suggesting that those intronic repeats did not contribute to genetic susceptibility to the tremor in JME. Further studies are required to identify the factors associated with this phenotype.