Abstract
We have recently described a child who presented early in life with homocystinuria and megaloblastic anemia. Fibroblasts from this patient had low levels of methylcobalamin (CH3-B12) and a decreased incorporation of (14C) methyltetrahydrofolate (CH3-THF) into methionine which was unresponsive to the addition of vitamin B12 to the tissue culture medium. In contrast to the cultured cells, in the patient the megaloblastic anemia and homocystinuria resolved on treatment with OH-B12. Fibroblasts from the parents of this patient had normal levels of CH3-B12 but intermediate levels of CH3-THF incorporation and a variable response to vitamin B12 in the culture medium. When the pro-band's mother became pregnant, prenatal diagnosis was attempted. The incorporation of total vitamin B12 derivatives which was CH3-B12 in the fetal amniocytes was only 7.4%, as compared to 26.1% and 48.7% in control amniocytes, and 37.1% and 32% in fibroblasts from the obligate heterozygotes. Values for CH3-THF incorporation were variable. Because the proband responded well to vitamin B12 therapy, it was decided to treat the mother prenatally. She received IM hydroxycobalamin (OH-Cbl) 1 mg twice weekly beginning at 25 weeks gestation. Diagnostic studies on fibroblasts obtained at birth confirmed that the baby has CH3-B12 deficiency. The baby has been maintained on 1 mg IM OH-Cbl twice weekly and is clinically well.
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Rosenblatt, D., Cooper, B., Schmutz, S. et al. 852 PRENATAL VITAMIN B12 THERAPY OF A FETUS WITH METHYLCOBALAMIN DEFICIENCY. Pediatr Res 19, 252 (1985). https://doi.org/10.1203/00006450-198504000-00882
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DOI: https://doi.org/10.1203/00006450-198504000-00882