Any lissencephaly (disease) in which the cause of the disease is a mutation in the TMTC3 gene. The disease is lissencephaly 8 (MONDO_0014992, a Monarch Disease Ontology entry). Also known as: LIS8, TMTC3 lissencephaly (disease), lissencephaly (disease) caused by mutation in TMTC3, lissencephaly 8; LIS8, lissencephaly type 8.