Imerslund-Grasbeck Syndrome: A Case Report

Megaloblasc anemia is an uncommon problem in childhood most frequently associated with vitamin deficiency or gastrointesnal disease. The common causes of megaloblasc anemia are vitamin B12 (cobalamin) deficiency and folic acid deficiency. Familial selecve malabsorpon of vitamin B12 associated with proteinuria firstly was described by Imerslund (1960) and Grasbeck et al (1960) (Imerslund-Grasbeck syndrome). About 300 paents have been published worldwide, with new paents mostly appearing in eastern Mediterranean countries. However, lots of paents may be misdiagnosed.3 Imerslund-Grasbeck syndrome (IGS), an autosomal recessive disease, is associated with megaloblasc anemia and proteinuria. The diagnosis should be considered when three typical features (macrocyc anemia, decreased serum B12 level, and proteinuria) are present. Symptoms may appear from the 4th month of age (not immediately a!er birth as in transcobalamin deficiency) up to several years later. The cause is a defect in the receptor of the vitamin B12-intrinsic factor complex on the ileal enterocytes. In most cases, the molecular basis of the selecve malabsorpon and proteinuria involves a mutaon in one of two genes, cubilin (CUBN) on chromosome 10 or amnionless (AMN) on chromosome 14. Both proteins are components of the intesnal receptor for the vitamin B12intrinsic factor complex and the receptor mediang the tubular reabsorpon of protein from intraglomerular filtrate. Management includes life-long vitamin B12 injecons, resulng in a long healthy life. Nevertheless, proteinuria persists. To diagnose the disease, it is important to be aware that cobalamin deficiency affects enterocyte funcon; therefore, all tests suggesng general and cobalamin malabsorpon should be repeated a!er resolving the deficiency.