Homocystinuria-megaloblastic anemia CBLE complementation type in infante: a case report

*Correspondence: [e-mail].

Abstract

Case Presentation: Patient, 1-month-old ALFP, born at term without intercurrences. In the first week of life, she sought medical care with maternal complaints of pallor, persistent crying and refusal to breastfeed, verified in a hemoglobin test of 4.5 g/dl, in addition to severe dysphagia in a contrast-enhanced test. In myelogram, the presence of partial true megaloblastic transformation and expressive magaloblastic disposition was observed. Evidenced in image exam global atrophy, both infra and supra tentorial, with signs of periventricular parenchymal hypodensity to the lateral ventricles. The diagnosis of Homocystinuria – Megaloblastic Anemia cblE came after a genetic panel with 2 verified in the MTRR gene (p.Gly548Alafs*2 and p.Lys382Glu), one known to be pathogenic and the other, until then, of uncertain clinical significance, interpreted as compound heterozygosity. The patient evolved with global delay in neuropsychomotor development. Initiate gained with vitamin B12, with hematimetric normalization, in addition to gains in cognitive and motor development.

Discussion: Megaloblastic anemia-homocystinuria (cblE type) is an autosomal recessive inborn error of metabolism resulting from defects in the cobalamin (vitamin B12) dependent pathway that converts homocysteine to methionine - catalyzed by methionine synthase (MTR). The clinic is heterogeneous and depends on the age of onset of symptoms, but neurological and hematological manifestations predominate. The confirmation of the diagnosis is through studies of the enzymatic activity and the complementary genetic analysis allows to distinguish the 3 CbIC groups. CbID and CbF. The treatment is based on the intramuscular administration of hydroxycobalamin. Other therapeutic adjuvants can be used, such as betaine, folic acid, carnitine and moderate protein restriction, with different results.

Final Comments: The presentation of this report intends to address a rare inborn error of metabolism, but there is a simple treatment that installs early and later complications and major clinical ones. In addition, we present the description of a new mutation of unknown significance.

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Artikel online veröffentlicht:
12. Mai 2025