Fanconi-Bickel syndrome in two Palestinian children: marked phenotypic variability with identical mutation

Fanconi-Bickel syndrome (FBS, OMIM 227810) is a rare autosomal recessive disease caused by a deficiency of glucose transporter 2 (GLUT2), a member of the facilitative glucose transporter family (Santer et al. J Inherit Metab Dis 21:191-194, 1998). The typical clinical picture is characterized by hepatorenal glycogen accumulation resulting in hepato- and nephromegaly, impaired utilization of glucose and galactose, proximal renal tubular dysfunction, rickets and severe short stature.

We report 2 Palestinian patients from 2 families who were homozygous for the mutation p.R301X (C>T) in exon 7of GLUT2 gene. Patient 1 showed clinical and laboratory improvement with age characterized by normal growth and resolution of rickets. Patient 2 had severe phenotype characterized by progressive weight loss, persistent metabolic acidosis, marked polyuria and clinical and laboratory findings of rickets progressing to death at age 10 months.

This report further expands the clinical spectrum of FBS even with identical mutations. Other yet unknown genetic, environmental or stochastic factors may be responsible for phenotypic variability.