Diverse Clinical manifestations of Cobalamin C Metabolism Disorders.

Cobalamin, commonly known as vitamin B12, is a crucial micronutrient synthesized predominantly by a few microorganisms. In the human body, Vitamin B12 (Cobalamin) is essential for DNA synthesis and is required as a cofactor for functioning two crucial enzymes, methylmalonyl-CoA mutase and methionine synthase. The deficiency in these cobalamin-derivated coenzymes leads to enzyme activity dysfunction and an accumulation of their respective substrates, methylmalonic acid, and homocysteine,harming the brain and many other organs. Furthermore, deficiency in this micronutrient can lead to a wide spectrum of hematologic and neuropsychiatric disorders. In addition to vitamin B12 deficiency, some genetic disorders block the intracellular processing of Cobalamin to its cofactors and lead to symptoms somewhat similar to vitamin B12 deficiency. These disorders are called Cobalamin metabolism disorders. Many of them are reversible when diagnosed early and treated promptly. This group's most common and well-understood disease is Cobalamin C (CblC) metabolism disorder. This case series report aimed to provide a comprehensive overview of diverse clinical presentations within the spectrum of CblC metabolism disorder and the introduction of two cases of late-onset presentation with ataxia and repeated seizures as the first manifestation of the disorder. Few case reports are available, specifically in children, describing cerebellar ataxia and seizure as the first manifestations of late-onset CblC metabolism disorder. Additionally, this report sought to contribute to the existing literature by highlighting potential areas for timely recognition and targeted clinical and therapeutic interventions, thereby enhancing the comprehensive care and support for individuals affected by CblC metabolism disorder.