Molecular characterisation of acute intermittent porphyria in a cohort of South African patients and kinetic analysis of two expressed mutants
| Autor: | Philip H. Fortgens, P.N. Meissner, Mark W. Sonderup, Elaine Pienaar, C Wendy Spearman, Anne V. Corrigall |
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| Rok vydání: | 2016 |
| Předmět: |
Male
0301 basic medicine medicine.medical_specialty Hydroxymethylbilane Synthase Mutant Black People Gene mutation Biology medicine.disease_cause Pathology and Forensic Medicine Cohort Studies South Africa 03 medical and health sciences Molecular genetics medicine Humans Gene Acute intermittent porphyria Genetics Mutation General Medicine medicine.disease Molecular biology 030104 developmental biology Porphyria Acute Intermittent Mutation testing Female |
| Zdroj: | Journal of Clinical Pathology. 70:515-520 |
| ISSN: | 1472-4146 0021-9746 |
| DOI: | 10.1136/jclinpath-2016-203907 |
| Popis: | Aims Acute intermittent porphyria (AIP) is a disorder of the haem biosynthetic pathway caused by mutations in the hydroxymethylbilane synthase ( HMBS ) gene. Knowledge of the spectrum of mutations present in South Africa is limited. This study presents the molecular profile of 20 South African patients with AIP, and the kinetic analysis of one novel expressed mutated HMBS enzyme and a previously identified mutation at the same position. Methods Genomic DNA was isolated from affected probands and selected family members, the HMBS gene amplified and mutations characterised by direct sequencing and restriction enzyme analysis. One of the novel mutations (p.Lys98Glu), a previously characterised mutation at the same position (p.Lys98Arg), and the wild-type enzyme were expressed, purified and subjected to partial kinetic characterisation. Results Four new mutations, p.Lys98Glu, p.Asp230Aspfs * 20, c.161-1G>A and c.422+3_6delAAGT, are described. Seven previously described mutations were found, while four patients revealed no mutations. Mutation analysis of five offspring of one of the probands carrying the p.Trp283X mutation revealed two asymptomatic carriers. Kinetic analysis showed that the p.Lys98Glu mutation results in loss of substrate affinity, whereas the previously described p.Lys98Arg mutation causes the loss of binding between the enzyme and its dipyrromethane cofactor, rendering the enzyme inactive. Conclusions This study comprises the most comprehensive characterisation of HMBS gene mutations in patients with AIP in South Africa. The biochemical characterisation of expressed HMBS mutants reveals insight into the mechanism of catalytic activity loss, which may inspire investigation into individualised therapy based on the molecular lesion identified. |
| Databáze: | OpenAIRE |
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