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J Clin Lipidol. 2015 Nov-Dec;9(6):837-846. doi: 10.1016/j.jacl.2015.09.001. Epub 2015 Sep 18.

A complex phenotype in a child with familial HDL deficiency due to a novel frameshift mutation in APOA1 gene (apoA-IGuastalla).

Author information

1
Department of Internal Medicine, University of Genoa, Genoa, Italy.
2
Center E. Grossi Paoletti, Department of Pharmacological and Biomolecular Sciences, University of Milan, Milan, Italy.
3
Department of Pharmacy, University of Parma, Parma, Italy.
4
Department of Pharmacy, University of Genoa, Genoa, Italy.
5
Laboratory of Human Genetics, Galliera Hospital, Genoa, Italy.
6
Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy. Electronic address: sebcal@unimore.it.
7
Department of Internal Medicine, University of Genoa, Genoa, Italy. Electronic address: stefbert@unige.it.

Abstract

BACKGROUND:

We describe a kindred with high-density lipoprotein (HDL) deficiency due to APOA1 gene mutation in which comorbidities affected the phenotypic expression of the disorder.

METHODS:

An overweight boy with hypertriglyceridemia (HTG) and HDL deficiency (HDL cholesterol 0.39 mmol/L, apoA-I 40 mg/dL) was investigated. We sequenced the candidate genes for HTG (LPL, APOC2, APOA5, GPIHBP1, LMF1) and HDL deficiency (LCAT, ABCA1 and APOA1), analyzed HDL subpopulations, measured cholesterol efflux capacity (CEC) of sera and constructed a model of the mutant apoA-I.

RESULTS:

No mutations in HTG-related genes, ABCA1 and LCAT were found. APOA1 sequence showed that the proband, his mother and maternal grandfather were heterozygous of a novel frameshift mutation (c.546_547delGC), which generated a truncated protein (p.[L159Afs*20]) containing 177 amino acids with an abnormal C-terminal tail of 19 amino acids. Trace amounts of this protein were detectable in plasma. Mutation carriers had reduced levels of LpA-I, preβ-HDL and large HDL and no detectable HDL-2 in their plasma; their sera had a reduced CEC specifically the ABCA1-mediated CEC. Metabolic syndrome in the proband explains the extremely low HDL cholesterol level (0.31 mmol/L), which was half of that found in the other carriers. The proband's mother and grandfather, both presenting low plasma low-density lipoprotein cholesterol, were carriers of the β-thalassemic trait, a condition known to be associated with a reduced low-density lipoprotein cholesterol and a reduced prevalence of cardiovascular disease. This trait might have delayed the development of atherosclerosis related to HDL deficiency.

CONCLUSIONS:

In these heterozygotes for apoA-I truncation, the metabolic syndrome has deleterious effect on HDL system, whereas β-thalassemia trait may delay the onset of cardiovascular disease.

KEYWORDS:

APOA1 mutation; Hypertriglyceridemia; Metabolic syndrome; Truncated apoA-I; β-thalassemia trait

PMID:
26687706
DOI:
10.1016/j.jacl.2015.09.001
[Indexed for MEDLINE]
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