Fanconi-Bickel syndrome (FBS) is a rare autosomal recessive disorder characterised by impaired
glucose liver homeostasis and
proximal renal tubular dysfunction. It is caused by pathogenic variants in SLC2A2 coding for the
glucose transporter GLUT2. Main clinical features include
hepatomegaly, fasting hypoglycaemia, postprandial hyperglycaemia, Fanconi-type tubulopathy occasionally with
rickets, and a severe
growth disorder. While treatment for renal tubular dysfunction is well established, data regarding optimal nutritional
therapy are scarce. Similarly, detailed clinical evaluation of treated FBS patients is lacking. These unmet needs were an incentive to conduct the present pilot study. We present clinical findings, laboratory parameters and molecular genetic data on 11 FBS patients with emphasis on clinical outcome under various nutritional interventions. At diagnosis, the patients' phenotypic severity could be classified into two categories: a first group with severe growth failure and
rickets, and a second group with milder signs and symptoms. Three patients were diagnosed early and treated because of family history. All patients exhibited massive glucosuria at diagnosis and some in both groups had fasting hypoglycaemic episodes. Growth retardation improved drastically in all five patients treated by intensive nutritional intervention (nocturnal
enteral nutrition) and uncooked
cornstarch with final growth parameters in the normal range. The four severely affected patients who were treated with uncooked
cornstarch alone did not catch up growth. All patients received
electrolytes and
l-carnitine supplementation to compensate for the tubulopathy. This is one of the largest series of FBS on therapeutic management with evidence that nocturnal
enteral nutrition rescues growth failure.