LETTERS TO THE EDITOR

 

A long-term follow-up of an Imerslund-Grasbeck syndrome patient with proteinuria

 

 

Correspondence

 

 

Dear Editor,

Imerslund-Grasbeck syndrome (IGS) is a rare autosomal recessive disorder characterized by megaloblastic anemia due to selective vitamin B₁₂ malabsorption and asymptomatic proteinuria.¹ IGS occurs in the first 1-2 years of the life and megalablostic anemia is responsive to parenteral vitamin B₁₂ treatment.² It is thought that proteinuria is benign in IGS; however, there is no sufficient number of follow-up series in IGS.

 

Case report

A 22-year-old woman had been referred to our pediatric outpatient clinic with the complaints of pale skin, loss of appetite, ataxia and diarrhea-constipation periods when she was 2-year-old. The clinical examination and laboratory studies revealed pallor of conjunctiva, megaloblastic anemia with vitamin B12 deficiency (serum vitamin B₁₂ level <150pg/ml, hemoglobin: 6.5g/dl, MCV: 104fl and peripheral blood smear with hypersegmented neutrophils) and mild proteinuria (less than 0.5g/day) with absence of kidney function abnormality. Two renal biopsies were performed because of persistent proteinuria, however, there was no remarkable histologically changes. She was diagnosed with IGS in the light of this clinical picture. Anemia and neurological symptoms were improved with vitamin B12 therapy in the next few weeks. Mild proteinuria remains persist with normal kidney function and she is being still followed-up with periodically for proteinuria.

IGS was firstly described in 1960 by Olga Imerslund and more than 300 cases have been published to date. In IGS, vitamin B₁₂ is completely abolished and if untreated with parenteral therapy the disease is fatal. A recent study revealed a biallelic mutation either in cubulin or amnions less genes cause IGS.³ Both proteins act as a receptor for intrinsic factor-vitamin B₁₂ complexes as well as cubulin is an albumin binding protein important for renal tubular albumine reabsorption.⁴ Because of absence of glomerular damage in kidney biopsies progressive kidney disease is not usual. Broch et al enrolled 14 patients to a long term follow-up study and exhibited no deterioration in kidney function.⁵ Limited numbers of cases have been observed almost 50 years and renal prognosis is excellent. We aimed to announce our case with IGS who has a good renal prognosis over 20 years follow-up.

 

Conflict of interest

The authors declare that there is no conflict of interest associated with this manuscript.

 

Zafer Ercan¹, Mehmet E. Demir², Turgay Ulas³, Muharrem Ingec³, Mehmet Horoz^2
1 Department of Nephrology. Yildirim Beyazid Training and Research Hospital. Ankara (Turkey)
² Department of Nephrology. Harran University, School of Medicine. Sanliurfa (Turkey)
³ Department of Internal Medicine. Harran University, School of Medicine. Sanliurfa (Turkey)

 

References

1. Imerslund O. Idiopathic chronic megaloblastic anemia in children. Acta Paediatr Suppl 1960;49(Suppl 119):1-115.         [ Links ]

2. Bonfin C, Strapasson E, Dellê LA, Malvezzi M, Moreira VA, Netto AG, et al. Imerslund-Gräsbeck syndrome: report of two cases. J Pediatr (Rio J) 1999;75(6):477-80.         [ Links ]

3. Fyfe JC, Madsen M, Højrup P, Christensen EI, Tanner SM, de la Chapelle A, et al. The functional cobalamin (vitamin B12)-intrinsic factor receptor is a novel complex of cubilin and amnionless. Blood 2004;103(5):1573-9.         [ Links ]

4. Birn H, Fyfe JC, Jacobsen C, Mounier F, Verroust PJ, Orskov H, et al. Cubilin is an albumin binding protein important for renal tubular albumin reabsorption. J Clin Invest 2000;105(10):1353-61.         [ Links ]

5. Broch H, Imerslund O, Monn E, Hovig T, Seip M. Imerslund-Gräsbeck anemia. Along-term follow-up study. Acta Paediatr Scand 1984;73(2):248-53.         [ Links ]

 

 

Correspondence:
Mehmet E. Demir,
Department of Nephrology,
Harran University,
School of Medicine,
Yenisehir campus,
63300, Sanliurfa, Turkey
demirmehmetemin@hotmail.com