The clinically most important variant is atypical (D70G) BChE because people with this variant have 2 hours of apnea after receiving a dose of succinylcholine that is intended to paralyze muscles for 3-5 minutes.
People homozygous for the Asp70His mutation are expected to have prolonged apnoea in response to succinylcholine or mivacurium, similar to people with the Asp70Gly mutation.