FAMILIAL SELECTIVE VITAMIN-B12 MALABSORPTION (IMERSLUND-GRASBECK SYNDROME) IN A POOL OF TURKISH PATIENTS

Thirty-six patients with Imerslund-Grasbeck syndrome are presented. Th e mean ages at presentation and diagnosis were 4.7 +/- 3.7 years and 7 .2 +/- 4.2 years, respectively. The mean hemoglobin level was 5.8 +/- 2.2 g/dL, the mean cell volume was 104.9 +/- 11.6 fL, the white blood cell count was 4479 +/- 2022/mm3, and the serum vitamin B12 level was 96.9 +/- 73 pg/mL. At diagnosis, 5 of the 36 patients, aged 5 to 16 ye ars, had neurologic symptoms. All the patients had severe megaloblasti c changes in bone marrow precursor cells. Proteinuria was detected in 78% of them. Patients with proteinuria had a younger age of onset (P < 0.0001) and diagnosis (P < 0.001) compared with those without protein uria. In all patients, vitamin B12 excretion unbound to intrinsic fact or after a flushing dose of vitamin B12 was lower than normal, and the re was no appreciable correction in urinary vitamin B12 excretion afte r binding of intrinsic factor. The impairment of vitamin B12 absorptio n studies in Schilling tests; however, showed great variation among pa tients. Serum haptoglobin values were close to zero in all patients, i ndicating the presence of that intravascular hemolysis in Imerslund-Gr asbeck syndrome. Variations among patients in the age of presentation, degree of impairment of vitamin B12 absorption, and presence or absen ce of proteinuria suggest a heterogeneity in etiology of Imerslund-Gra sbeck syndrome at the molecular level.