Butyrylcholinesterase genetic variability in Guarani Amerindians from the Brazilian state of Mato Grosso do Sul

Genetic mutations associated with susceptibility to perioperative complications in a longitudinal biorepository with integrated genomic and electronic health records

BACKGROUND

Existing genetic information can be leveraged to identify patients with susceptibilities to conditions that might impact their perioperative care, but clinicians generally have limited exposure and are not trained to contextualise this information. We identified patients with genetic susceptibilities to anaesthetic complications using a perioperative biorepository and characterised the concordance with existing diagnoses.

METHODS

Adult patients undergoing surgery within Michigan Medicine from 2012 to 2017 were consented for genotyping. Genotypes were integrated with the electronic health record (EHR). We retrospectively characterised frequencies of variants associated with butyrylcholinesterase deficiency, factor V Leiden, and malignant hyperthermia, three pharmacogenetic factors with perioperative implications. We calculated the percentage homozygous and heterozygous for each that had been diagnosed previously and searched for EHR findings consistent with a predisposition.

RESULTS

Analysis of genetic data revealed that 25 out of 40 769 (0.1%) patients were homozygous and 1918 (4.7%) were heterozygous for mutations associated with butyrylcholinesterase deficiency. Of the homozygous individuals, 14 (56%) carried a pre-existing diagnosis. For factor V Leiden, 29 (0.1%) were homozygous and 2153 (5.3%) heterozygous. Of the homozygous individuals, three (10%) were diagnosed by EHR-derived phenotype and six (21%) by clinician review. Malignant hyperthermia was assessed in a subset of patients. We detected two patients with associated mutations. Neither carried clinical diagnoses.

CONCLUSIONS

We identified patients with genetic susceptibility to perioperative complications using an open source script designed for clinician use. We validated this application in a retrospective analysis for three conditions with well-characterised inheritance, and showed that not all genetic susceptibilities were documented in the EHR.

Variability of the BCHE gene in Amerindians from Paraná, Brazil

OBJECTIVE

This study aims to better understand the variability of the BCHE gene, and regions adjacent to it, in different populations. More specifically, it also aims to analyze the diversity of this DNA segment among two Amerindian populations, whose distinct characteristics provide us an extremely interesting material for genetic, evolutionary and anthropological studies, since they diverge genetically and culturally in spite of a very close living relationship in space and time.

METHODS

The two Amerindian populations analysed were from Guarani-Mbyá and Kaingang ethnic groups, both from the Rio das Cobras indian reservation area (Paraná, Brazil). The other populations data were obtained from the HapMap Project data, NCBI data and previously studies. The variability of seven SNPs was analyzed: two downstream, three within and two upstream of the BCHE gene.

RESULTS

The number of different BCHE variants in Amerindians is lower than in other populations. The present data are in accordance with the genetic distance between Guarani and Kaingang, and from them to other populations. Some SNPs (rs3495, rs7624915 and rs4387996) presented an interesting frequency pattern, with a higher frequency of the ancestral allele in the region of the modern human origin and its frequency decreasing gradually, from Africa toward the Americas.

CONCLUSIONS

Despite the geographical coexistence throughout their dispersion, each of these two Amerindian groups retains a high degree of genetic identity, probably maintained by cultural and social isolation.

Two new mutations of the human BCHE gene (IVS3-14T>C and L574fsX576)

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.