Transplacentally Acquired Antibody to Intrinsic Factor with Vitamin B₁₂ Deficiency

A newborn infant was found to have circulating maternal intrinsic factor antibody in the same titer as his 41 year old mother, who had had known pernicious anemia since age 33. At 11 days of age, no intrinsic factor was demonstrable in the infant’s gastric juice; whether this was related to the presence of serum IF antibody or was a variant of normal is not certain. At three months of age, the infant had B₁₂ deficiency, manifested by a low serum B₁₂ level and hypersegmentation of the nuclei of the neutrophilic leukocytes, but the gastric biopsy was normal, as was the intrinsic factor secretion. Maternal antibody to intrinsic factor was no longer present.

These findings support the concepts that:

(1) Intrinsic factor antibody may accelerate the development of B₁₂ deficiency;

(2) The antibody may not, of itself, produce any permanent gastric damage.