Kidney and vascular function in adult patients with hereditary fructose intolerance

Nynke Simons,François-Guillaume Debray,Nicolaas C Schaper,Edith J.M Feskens,Carla E.M Hollak,Judith A.P Bons,Jörgen Bierau,Alfons J.H.M Houben,Casper G Schalkwijk,Coen D.A Stehouwer,David Cassiman,Martijn C.G.J Brouwers

doi:10.1016/j.ymgmr.2020.100600

Abstract

Objective: Previous studies have shown that patients with hereditary fructose intolerance (HFI) are characterized by a greater intrahepatic triglyceride content, despite a fructose-restricted diet. The present study aimed to examine the long-term consequences of HFI on other aldolase-B-expressing organs, i.e. the kidney and vascular endothelium.Methods: Fifteen adult HFI patients were compared to healthy control individuals matched for age, sex and body mass index. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (cf-PWV) and endothelial function by peripheral arterial tonometry, skin laser doppler flowmetry and the endothelial function biomarkers soluble E-selectin [sE-selectin] and von Willebrand factor. Serum creatinine and cystatin C were measured to estimate the glomerular filtration rate (eGFR). Urinary glucose and amino acid excretion and the ratio of tubular maximum reabsorption of phosphate to GFR (TmP/GFR) were determined as measures of proximal tubular function. Results: Median systolic blood pressure was significantly higher in HFI patients (127 versus 122 mmHg, p = .045). Pulse pressure and cf-PWV did not differ between the groups (p = .37 and p = .49, respectively). Of all endothelial function markers, only sE-selectin was significantly higher in HFI patients (p = .004). eGFR was significantly higher in HFI patients than healthy controls (119 versus 104 ml/min/1.73m2, p = .001, respectively). All measurements of proximal tubular function did not differ significantly between the groups.Conclusions: Adult HFI patients treated with a fructose-restricted diet are characterized by a higher sE-selectin level and slightly higher systolic blood pressure, which in time could contribute to a greater cardiovascular risk. The exact cause and, hence, clinical consequences of the higher eGFR in HFI patients, deserves further study.

Highlights

Hereditary fructose intolerance (HFI; OMIM# 229600) is an autosomal recessive metabolic disorder [1] with an estimated incidence of 1 in every 20,000 newborns [2]
Fifteen HFI patients and fifteen age, sex- and BMI-matched healthy controls were included in this study
Patients consumed almost no fructose and, as a consequence, protein and saturated fat intake were higher compared to healthy controls

Summary

Introduction

Hereditary fructose intolerance (HFI; OMIM# 229600) is an autosomal recessive metabolic disorder [1] with an estimated incidence of 1 in every 20,000 newborns [2]. HFI is caused by mutations in the gene encoding aldolase B (ALDOB) that is predominantly expressed in liver, kidney and small intestine [3]. Aldolase B (EC 4.1.2.13) catalyzes the conversion of fructose 1,6-bisphosphate and fructose 1-phosphate to glyceraldehyde (3-phosphate) and dihydroxyacetone phosphate [4]. Fructose ingestion in HFI patients causes accumulation of fructose 1phosphate, and intracellular phosphate and ATP depletion, resulting in acute and chronic cellular dysfunction. Chronic exposure to fructose can result in cirrhosis, liver failure, generalized proximal tubular dysfunction (i.e. Fanconi syndrome), growth retardation or even death [5,6,7,8,9]

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