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Hereditary fructose intolerance
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<h2 id="presentation">Presentation</h2> <p>The key identifying feature of HFI is the appearance of symptoms with the introduction of <a href="/facts/Fructose/pEqWJC2N">fructose</a> to the diet.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a><a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> Affected individuals are asymptomatic and healthy, provided they do not ingest foods containing fructose or any of its common precursors, <a href="/facts/Sucrose/7y1ke94L">sucrose</a> and <a href="/facts/Sorbitol/LA9MsjYb">sorbitol</a>. In the past, infants often became symptomatic when they were introduced to <a href="/facts/Infant_formula/lrbUhzXV">formulas</a> that were sweetened with fructose or sucrose. These sweeteners are not common in formulas used today.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> Symptoms such as vomiting, nausea, restlessness, pallor, sweating, trembling and lethargy can also first present in infants when they are introduced to fruits and vegetables. These can progress to apathy, coma and convulsions if the source is not recognized early.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> </p><p>When patients are diagnosed with HFI, a dietary history will often reveal an aversion to fruit and other foods that contain large amounts of fructose. Most adult patients do not have any dental <a href="/facts/Caries/trECbk2z">caries</a>.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a><a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> </p> <h2 id="fructose-metabolism">Fructose metabolism</h2> <p>After ingestion, fructose is converted to <a href="/facts/Fructose-1-phosphate/Yoxj2UMc">fructose-1-phosphate</a> in the <a href="/facts/Liver/Rtp4Fk2b">liver</a> by <a href="/facts/Fructokinase/LCCSML3P">fructokinase</a>. Deficiencies of fructokinase cause <a href="/facts/Essential_fructosuria/Xg1RPPfB">essential fructosuria</a>, a clinically <a href="/facts/Benign/Xu5F9mRh">benign</a> condition characterized by the excretion of unmetabolized fructose in the urine. Fructose-1-phosphate is metabolized by <a href="/facts/Aldolase_B/vEQkIQXh">aldolase B</a> into dihydroxyacetone phosphate and <a href="/facts/Glyceraldehyde/M0GW5PPm">glyceraldehyde</a>. HFI is caused by a deficiency of aldolase B.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> </p><p>A deficiency of aldolase B results in an accumulation of fructose-1-phosphate, and trapping of phosphate (fructokinase requires <a href="/facts/Adenosine_triphosphate/nB9bwgcU">adenosine triphosphate</a> (ATP)). The downstream effects of this enzyme block are the inhibition of glucose production and reduced regeneration of ATP.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> </p> <h2 id="diagnosis">Diagnosis</h2> <p>Because of the ease of therapy (dietary exclusion of fructose), HFI can be effectively managed if properly diagnosed. In HFI, the diagnosis of <a href="/facts/Homozygote/XzEJ5gPp">homozygotes</a> is difficult, requiring a <a href="/facts/Genomic_DNA/UeLsDBlw">genomic DNA</a> screening with <a href="/facts/Allele/8FxCS9KA">allele</a>-specific probes or an <a href="/facts/Enzyme_assay/3SHu9GkN">enzyme assay</a> from a <a href="/facts/Liver_biopsy/HeVlkKFT">liver biopsy</a>. Once identified, parents of infants who carry mutant aldolase B alleles leading to HFI, or older individuals who have clinical histories compatible with HFI can be identified and counselled with regard to preventive therapy: dietary exclusion of foods containing fructose, sucrose, or sorbitol. If possible, individuals who suspect they might have HFI should avoid testing via fructose challenge as the results are non-conclusive for individuals with HFI, and even if the diagnostic administration of fructose is properly controlled, profound <a href="/facts/Hypoglycemia/BlAmuP6k">hypoglycemia</a> and its <a href="/facts/Sequela/VJ89GSoC">sequelae</a> can threaten the patient's well-being.<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> </p> <h2 id="treatment">Treatment</h2> <p>Treatment of HFI depends on the stage of the disease, and the severity of the symptoms. Stable patients without acute intoxication events are treated by careful dietary planning that avoids fructose and its metabolic precursors. Fructose is replaced in the diet by <a href="/facts/Glucose/oUSkoLCD">glucose</a>, <a href="/facts/Maltose/v43CVtaU">maltose</a> or other sugars. Management of patients with HFI often involves <a href="/facts/Dietitian/QykVpr91">dietitians</a> who have a thorough knowledge of what foods are acceptable.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Fructose_malabsorption/5UcNrcc7">Fructose malabsorption</a></li></ul> <h2 id="external-links">External links</h2> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Hereditary fructose intolerance". Genetic and Rare Disorders Information Center (GARD). National Institutes of Health. Retrieved April 17, 2018. <a href="https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance" target="_blank">https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Hereditary fructose intolerance". Genetic and Rare Disorders Information Center (GARD). National Institutes of Health. Retrieved April 17, 2018. <a href="https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance" target="_blank">https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Hereditary fructose intolerance". Genetic and Rare Disorders Information Center (GARD). National Institutes of Health. Retrieved April 17, 2018. <a href="https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance" target="_blank">https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"Hereditary fructose intolerance". Genetic and Rare Disorders Information Center (GARD). National Institutes of Health. Retrieved April 17, 2018. <a href="https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance" target="_blank">https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Kaiser, Ursula B.; Hegele, Robert A. (December 1991). "Case report: Heterogeneity of aldolase B in hereditary fructose intolerance". The American Journal of the Medical Sciences. 302 (6): 364–8. doi:10.1097/00000441-199112000-00008. PMID 1772121. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"ALDOB gene". Genetics Home Reference. U.S. National Library of Medicine. Retrieved April 17, 2018. <a href="https://ghr.nlm.nih.gov/gene/ALDOB#location" target="_blank">https://ghr.nlm.nih.gov/gene/ALDOB#location</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Gaughan S, Ayres L, Baker PR II (2021). "Hereditary Fructose Intolerance". (GeneReviews® [Internet]). Seattle: University of Washington. PMID 26677512. NBK333439. <a href="https://www.ncbi.nlm.nih.gov/books/NBK333439/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK333439/</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"Hereditary fructose intolerance". Genetic and Rare Disorders Information Center (GARD). National Institutes of Health. Retrieved April 17, 2018. <a href="https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance" target="_blank">https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"Hereditary fructose intolerance". Genetic and Rare Disorders Information Center (GARD). National Institutes of Health. Retrieved April 17, 2018. <a href="https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance" target="_blank">https://rarediseases.info.nih.gov/diseases/6622/hereditary-fructose-intolerance</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Gaughan S, Ayres L, Baker PR II (2021). "Hereditary Fructose Intolerance". (GeneReviews® [Internet]). Seattle: University of Washington. PMID 26677512. NBK333439. <a href="https://www.ncbi.nlm.nih.gov/books/NBK333439/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK333439/</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Steinmann, Beat; Santer, Rene (2012). "Disorders of Fructose Metabolism". In Saudubray, Jean-Marie; van den Berghe, Georges; Walter, John H. (eds.). Inborn Metabolic Diseases: Diagnosis and Treatment (5th ed.). Springer. pp. 157–165. ISBN 978-3-642-15719-6. <a href="978-3-642-15719-6" target="_blank">978-3-642-15719-6</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Online Mendelian Inheritance in Man (OMIM): Fructose Intolerance, Hereditary; HFI - 229600 <a href="/wiki/Online_Mendelian_Inheritance_in_Man" target="_blank">/wiki/Online_Mendelian_Inheritance_in_Man</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Steinmann, Beat; Santer, Rene (2012). "Disorders of Fructose Metabolism". In Saudubray, Jean-Marie; van den Berghe, Georges; Walter, John H. (eds.). Inborn Metabolic Diseases: Diagnosis and Treatment (5th ed.). Springer. pp. 157–165. ISBN 978-3-642-15719-6. <a href="978-3-642-15719-6" target="_blank">978-3-642-15719-6</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Steinmann, Beat; Santer, Rene (2012). "Disorders of Fructose Metabolism". In Saudubray, Jean-Marie; van den Berghe, Georges; Walter, John H. (eds.). Inborn Metabolic Diseases: Diagnosis and Treatment (5th ed.). Springer. pp. 157–165. ISBN 978-3-642-15719-6. <a href="978-3-642-15719-6" target="_blank">978-3-642-15719-6</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Steinmann, Beat; Santer, Rene (2012). "Disorders of Fructose Metabolism". In Saudubray, Jean-Marie; van den Berghe, Georges; Walter, John H. (eds.). Inborn Metabolic Diseases: Diagnosis and Treatment (5th ed.). Springer. pp. 157–165. ISBN 978-3-642-15719-6. <a href="978-3-642-15719-6" target="_blank">978-3-642-15719-6</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Online Mendelian Inheritance in Man (OMIM): Fructose Intolerance, Hereditary; HFI - 229600 <a href="/wiki/Online_Mendelian_Inheritance_in_Man" target="_blank">/wiki/Online_Mendelian_Inheritance_in_Man</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>Steinmann, Beat; Santer, Rene (2012). "Disorders of Fructose Metabolism". In Saudubray, Jean-Marie; van den Berghe, Georges; Walter, John H. (eds.). Inborn Metabolic Diseases: Diagnosis and Treatment (5th ed.). Springer. pp. 157–165. ISBN 978-3-642-15719-6. <a href="978-3-642-15719-6" target="_blank">978-3-642-15719-6</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Steinmann, Beat; Santer, Rene (2012). "Disorders of Fructose Metabolism". In Saudubray, Jean-Marie; van den Berghe, Georges; Walter, John H. (eds.). Inborn Metabolic Diseases: Diagnosis and Treatment (5th ed.). Springer. pp. 157–165. ISBN 978-3-642-15719-6. <a href="978-3-642-15719-6" target="_blank">978-3-642-15719-6</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>Kaiser, Ursula B.; Hegele, Robert A. (December 1991). "Case report: Heterogeneity of aldolase B in hereditary fructose intolerance". The American Journal of the Medical Sciences. 302 (6): 364–8. doi:10.1097/00000441-199112000-00008. PMID 1772121. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>Steinmann, Beat; Santer, Rene (2012). "Disorders of Fructose Metabolism". In Saudubray, Jean-Marie; van den Berghe, Georges; Walter, John H. (eds.). Inborn Metabolic Diseases: Diagnosis and Treatment (5th ed.). Springer. pp. 157–165. ISBN 978-3-642-15719-6. <a href="978-3-642-15719-6" target="_blank">978-3-642-15719-6</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> </ol>