hydroxocobalamin and Nephrotic-Syndrome

Cobalamin C (CblC) defects are inherited autosomal recessive disorders of vitamin B12 metabolism due to mutations in the MMACHC gene. Renal manifestations include thrombotic microangiopathy (TMA), acute or chronic renal failure, tubulointerstitial nephritis, and proximal renal tubular acidosis. However, reports about glomerular pathologies are scarce.. A 4-year-old boy presented with nephrotic syndrome, arterial hypertension, and chronic anemia but no signs of hemolysis. Renal biopsy showed TMA with ischemic glomerular collapse, foot process effacement, and tubulointerstitial fibrosis. Elevated serum levels of homocysteine suggested a cobalamin C disorder. This was confirmed by the identification of compound heterozygous mutations in the MMACHC gene. Initial therapy consisted of antihypertensive treatment including angiotensin converting enzyme inhibitor (ACEi) leading to blood pressure control and a significant reduction of proteinuria. After a definite diagnosis of CblC deficiency, hydroxocobalamin was introduced. Thereafter, homocysteine levels decreased, anemia resolved, and a further decline of proteinuria with normalization of serum protein levels was noted. Renal function remained stable.. Although uncommon, the clinical picture of CblC defects may be ruled by nephrotic syndrome mimicking glomerulonephritis, minimal change disease, or primary focal and segmental glomerulosclerosis. Key to a correct diagnosis is elevated serum levels of homocysteine, and a definite diagnosis can be confirmed by genetic testing.

Topics: Anemia; Angiotensin-Converting Enzyme Inhibitors; Biopsy; Carrier Proteins; Child, Preschool; Homocysteine; Humans; Hydroxocobalamin; Hypertension, Renal; Kidney; Male; Nephrotic Syndrome; Oxidoreductases; Thrombotic Microangiopathies; Vitamin B 12; Vitamin B 12 Deficiency

cblC disease is a cause of hemolytic uremic syndrome (HUS), which has been primarily described in neonates and infants with severe renal and neurological lesions.. Two sisters aged 6 and 8.5 years presented with a latent hemolytic process characterized by undetectable or low plasma haptoglobin, respectively, associated with renal failure and gross proteinuria. Renal biopsies performed in both patients found typical findings of thrombotic microangiopathy suggesting the diagnosis of HUS. Both patients were free of neurologic signs.. Biochemical investigations found a cobalamin processing deficiency of the cblC type. Search for additional factors susceptible to worsen endothelial damage revealed homozygosity 677C--> T mutation in the methylenetetrahydrofolate reductase gene as well as heterozygosity for a 3254T--> C mutation in factor H in the patient with the most severe clinical presentation. Long-term subcutaneous administration of hydroxocobalamin in combination with oral betaine and folic acid resulted in clinical and biological improvement in both patients.. cblC disease may be a cause of chronic HUS with delayed onset in childhood. Superimposed mutation of factor H gene might influence clinical severity.

Topics: Anemia; Betaine; Child; Combined Modality Therapy; Complement Factor H; Drug Therapy, Combination; Endothelium, Vascular; Female; Folic Acid; Genetic Predisposition to Disease; Genotype; Haptoglobins; Hemolytic-Uremic Syndrome; Humans; Hydroxocobalamin; Hypertension; Kidney; Methylenetetrahydrofolate Reductase (NADPH2); Mutation, Missense; Nephrotic Syndrome; Plasma Exchange; Point Mutation; Proteinuria; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-cbl; Renal Dialysis; Vitamin B 12