Some types of [http://www.epilepsy.com/ epilepsy] may be brought on due to a splice site mutation.
In addition to a mutation in a stop codon,  a splice site mutation on the 3' strand was found in a gene coding for cystatin B in Progressive Myoclonus Epilepsy patients. This combination of mutations was not found in unaffected individuals. By comparing sequences with and without the splice site mutation, investigators were able to determine that a G-to-C nucleotide transversion occurs at the last position of the first intron. This transversion occurs in the region that codes for the cystatin B gene. Individuals suffering from Progressive Myoclonus Epilepsy possess a mutated form of this gene, which results in decreased output of mature mRNA, and subsequently decreases in protein expression.
A study has also shown that a type of Childhood Absence Epilepsy (CAE) causing febrile seizures may be linked to a splice site mutation in the sixth intron of the [https://www.ncbi.nlm.nih.gov/gene/2566 GABRG2 gene].  This splice site mutation was found to cause a nonfunctional GABRG2 subunit in affected individuals. According to this study, a point mutation was the culprit for the splice-donor site mutation, which occurred in intron 6. A nonfunctional protein product is produced, leading to the also nonfunctional subunit.