IVS3E4-14C I3E4-14C altered splicing between Intron 3 and exon 4, nt -14 at the acceptor site of intron 2, T>C found in cis with G115D(G143D) in a patient it is expected that this mutation does not alter splicing process
The genetic variation of human butyrylcholinesterase is associated with the majority of prolonged cases of apnea in patients submitted to the muscle relaxant succinylcholine. The present study reports two new mutations of the BCHE gene in 346 Euro-Brazilians: IVS3-14T>C found in five heterozygotes (allele frequency: 0.72+/-0.32%) and L574fsX576 found in one heterozygote (allele frequency: 0.14+/-0.14%). These two variants were not found in 85 Guarani Amerindians. It is not expected that the IVS3-14T>C mutation may interfere in the splicing process and that the mutation found in exon 4 (L574fsX576) may disturb BChE tetramerization and activity.
Title: Two novel mutations in the BCHE gene in patients with prolonged duration of action of mivacurium or succinylcholine during anaesthesia Gatke MR, Bundgaard JR, Viby-Mogensen J Ref: Pharmacogenet Genomics, 17:995, 2007 : PubMed
BACKGROUND: Butyrylcholinesterase (BChE) hydrolyses the neuromuscular blocking agents, succinylcholine and mivacurium used during general anaesthesia. Hereditary low BChE activity may result in an extensively prolonged duration of action of these drugs, especially in patients who are homozygous for the atypical or silent variants. We present three novel mutations in the butyrylcholinesterase gene (BCHE) identified in three families in which a member had experienced severely prolonged duration of action of succinylcholine. METHODS: As the phenotypes of the three probands could not be established with certainty using conventional biochemical tests, DNA samples were collected from two of the probands and four relatives. Genotypes were determined using complete nucleotide sequencing. RESULTS: Three novel mutations were identified: BCHE*FS126, BCHE*I3E4-14C and BCHE*328D. The proband in family 1 was genotyped as BCHE*115D*I3E4-14C/BCHE*FS126, whereas the proband in family 3 was compound heterozygous for BCHE*328D and BCHE*142M. In both patients, BChE activity was below detection limit, and they experienced an extensively prolonged duration of action of succinylcholine. The proband in family 2 was not sequenced, but a relative was heterozygous for BCHE*FS126. BCHE*I3E4-14C was in linkage with a known silent variant. CONCLUSIONS: Two novel variants of BCHE are silencing the enzyme function. BCHE*FS126 results in a truncated protein lacking the active site and is therefore inactive. The second variant is BCHE*328D, also resulting in an inactive protein, as this change in amino acid is radical and furthermore situated in the gorge harbouring the active site. These variants result in extensively prolonged duration of action of succinylcholine.
