A patient with an inborn error of vitamin B12 metabolism (cblF) detected by newborn screening.

[homocystinuria without methylmalonic aciduria]

A neonate , who was found to have an elevated C 3 /C 2 ratio and minimally elevated propionylcarnitine on newborn screening , was subsequently identified as having the rare cblF inborn error of vitamin B 12 (cobalamin ) metabolism . This disorder is characterized by the retention of unmetabolized cobalamin in lysosomes such that it is not readily available for cellular metabolism . Although cultured fibroblasts from the patient did not show the expected functional abnormalities of the cobalamin-dependent enzymes , methylmalonyl-CoA mutase and methionine synthase , they did show reduced synthesis of the active cobalamin cofactors adenosylcobalamin and methylcobalamin . Mutation analysis of LMBRD 1 established that the patient had the cblF disorder . Treatment was initiated promptly , and the patient showed a robust response to regular injections of cyanocobalamin , and she was later switched to hydroxocobalamin . Currently , at 3 years of age , the child is clinically well , with appropriate development . Adjusted newborn screening cutoffs in Ontario allowed detection of a deficiency that might not have otherwise been identified , allowing early treatment and perhaps preventing the adverse sequelae seen in some untreated patients .

Diseases
Validation

Diseases presenting "early treatment" symptom

acute rheumatic fever

allergic bronchopulmonary aspergillosis

benign recurrent intrahepatic cholestasis

cowden syndrome

fabry disease

familial mediterranean fever

homocystinuria without methylmalonic aciduria

kallmann syndrome

krabbe disease

omenn syndrome

phenylketonuria

pyomyositis

scrub typhus

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