ClinVar Miner

Submissions for variant NM_000229.2(LCAT):c.997G>A (p.Val333Met) (rs776035233)

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Total submissions: 1
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Submitter RCV SCV Clinical significance Condition Last evaluated Review status Method Comment
Unidad de Genómica Médica UC, Pontificia Universidad Católica de Chile RCV000782355 SCV000899250 pathogenic Norum disease 2019-04-29 criteria provided, single submitter research Methods: An adult female proband with hypoalphalipoproteinemia, corneal opacity and mild anemia, as well as her first-degree relatives, were recruited for clinical, biochemical, genetic, in-silico and in-vitro LCAT analysis. Sequencing of exons and intron-exon boundaries was performed to identify mutations. Site-directed mutagenesis was carried out to generate plasmids containing cDNA with wild type or mutant sequences. Such expression vectors were transfected to HEK-239T cells to asses the effect of LCAT variants in expression, synthesis, secretion and enzyme activity. In silico prediction analysis and molecular modeling was also used to evaluate the effect of LCAT variants. Results: LCAT sequencing identified rare p.V333M and p.M404V missense mutations in compound heterozygous state in the proband, as well the common synonymous p.L363L variant. LCAT protein was detected in proband's plasma, but with undetectable enzyme activity compared to control relatives. HEK-239T transfected cells with vector expression plasmids containing either p.M404V or p.V333M cDNA showed detectable LCAT protein expression both in supernatants and lysates from cultured cells, but with much lower enzyme activity compared to cells transfected with the wild-type sequence. Bioinformatic analyses also supported a causal role of such rare variations in LCAT lack of function. Conclusion: Genetic, biochemical, in vitro and in silico analyses indicate that the rare mutations p.M404V and p.V333M in LCAT gene lead to suppression of LAT enzyme activity and cause clinical features of familial LCAT deficiency.

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