Vitamin B12 Deficiency in Infants With Axial Hypotonia and Psychomotor Regression: Insights From a Moroccan Case Study.

Vitamin B12 deficiency is a rare entity in the pediatric population. It is often of maternal origin in exclusively breast-fed infants. Its clinical manifestations are multiple and unspecific, encompassing hematological problems and neurodevelopmental consequences. Positive diagnosis and early treatment with vitamin B12 supplementation have a rapidly reversible effect on symptoms. Delayed diagnosis, however, may result in irreversible neurological sequelae. We report the case of a six-month-old infant, admitted with hypotonia and psychomotor regression since the age of four months. The laboratory work-up revealed macrocytic anemia with the presence of megakaryocytes and megaloblasts on the myelogram. Vitamin B12 levels were low, and homocysteine levels were high. A maternal workup showed vitamin B12 deficiency in the mother. A brain MRI showed bilateral frontoparietal cortical atrophy. The patient was put on vitamin B12 supplementation with good evolution. The aim of our work is to shed light on the misleading and varied clinical profile of vitamin B12 deficiency in an exclusively breastfed infant, the serious consequences of maternal vitamin B12 deficiency, and the importance of early diagnosis of this condition.