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Title: Homozygosity for aquaporin 7 G264V in three unrelated children with hyperglyceroluria and a mild platelet secretion defect
Authors: Goubau, Christophe ×
Jaeken, Jaak
Levtchenko, Elena
Thys, Chantal
Di Michele, Michela
Martens, Geert A
Gerlo, Erik
De Vos, Rita
Buyse, Gunnar
Goemans, Nathalie
Van Geet, Chris
Freson, Kathleen #
Issue Date: Jan-2013
Publisher: Williams & Wilkins
Series Title: Genetics in Medicine vol:15 issue:1 pages:55-63
Article number: 10.1038/gim.2012.90
Abstract: Purpose:Aquaporin 7 (AQP7) belongs to the aquaglyceroporin family, which transports glycerol and water. AQP7-deficient mice develop obesity, insulin resistance, and hyperglyceroluria. However, AQP7's pathophysiologic role in humans is not yet known.Methods:Three children with psychomotor retardation and hyperglyceroluria were screened for AQP7 mutations. The children were from unrelated families. Urine and plasma glycerol levels were measured using a three-step enzymatic approach. Platelet morphology and function were studied using electron microscopy, aggregations, and adenosine triphosphate (ATP) secretion tests.Results:The index patients were homozygous for AQP7 G264V, which has previously been shown to inhibit transport of glycerol in Xenopus oocytes. We also detected a subclinical platelet secretion defect with reduced ATP secretion, and the absence of a secondary aggregation wave after epinephrine stimulation. Electron microscopy revealed round platelets with centrally located granules. Immunostaining showed AQP7 colocalization, with dense granules that seemed to be released after strong platelet activation. Healthy relatives of these patients, who were homozygous (not heterozygous) for G264V, also had hyperglyceroluria and platelet granule abnormalities.Conclusion:The discovery of an association between urine glycerol loss and a platelet secretion defect is a novel one, and our findings imply the involvement of AQPs in platelet secretion. Additional studies are needed to define whether AQP7 G264V is also a risk factor for mental disability.Genet Med advance online publication 16 August 2012.
URI: 
ISSN: 1098-3600
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Growth, Proliferation, Child and Adolescent (-)
Neuro-musculo-skeletal Research (-)
Molecular and Vascular Biology
× corresponding author
# (joint) last author

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