Any hereditary hyperekplexia in which the cause of the disease is a mutation in the SLC6A5 gene. The disease is hyperekplexia 3 (MONDO_0013827, a Monarch Disease Ontology entry). Also known as: HKPX3, SLC6A5 hereditary hyperekplexia, hereditary hyperekplexia caused by mutation in SLC6A5, hyperekplexia type 3.