Infantile Tremor Syndrome: A Vitamin B12 Deficiency Syndrome in Infants

Abstract

Twenty-three patients of infantile tremor syndrome were studied. Clinically, all of them presented with tremors, pallor, skin pigmentation, regression of milestones, and subnormal developmental quotient (80 per cent). Laboratory findings revealed anaemia in 91 per cent, low serum vitamin B12 levels in 87 per cent, reduced serum iron in about 50 per cent and reduced red cell folate in 9 per cent. Vitamin B12 deficiency was demonstrable either by conventional criteria or by use of the deoxyuridine (dU) suppression test in all patients. Erythropolesis was megaloblastic in 20/23 patients and in ten patients, including the three with normoblastic erythropoiesis, cellular deficiency of vitamin Bl2 was revealed by the dU suppression test performed on bone marrow cultures. In the cerebrospinal fluid (CSF) transcobalamin II (TC II), the active transport protein for vitamin Bl2, was reduced significantly (P<0.05), although transcobalamins in the blood did not reveal any statistically significant difference from the control group. Furthermore, levels of vitamin B12 in CSF were also significantly reduced (P<0.005). The low levels of vitamin B12 and its transport protein TC II in the CSF may be responsible for the neurological features of this syndrome.