title: Cobalamin C deficiency in an adolescent with altered mental status and anorexia.
abstract: Although cobalamin (cbl) C deficiency is the most common inherited disorder of vitamin B12 metabolism, the late-onset form of the disease can be difficult to recognize because it has a broad phenotypic spectrum. In this report, we describe an adolescent female exposed to unknown illicit substances and sexual abuse who presented with psychosis, anorexia, seizures, and ataxia. The patient's diagnosis was delayed until a metabolic workup was initiated, revealing hyperhomocysteinemia, low normal plasma methionine, and methylmalonic aciduria. Ultimately, cblC deficiency was confirmed when molecular testing showed compound heterozygosity for mutations (c.271dupA and c.482G>A) in the MMACHC gene. This diagnosis led to appropriate treatment with hydroxocobalamin, betaine, and folate, which resulted in improvement of her clinical symptoms and laboratory values. This patient demonstrates a previously unrecognized presentation of late-onset cblC deficiency. Although neuropsychiatric symptoms are common in late-onset disease, seizures and cerebellar involvement are not. Furthermore, anorexia has not been previously described in these patients. This case emphasizes that inborn errors of metabolism should be part of the differential diagnosis for a teenager presenting with altered mental status, especially when the diagnosis is challenging or neurologic symptoms are unexplained. Correct diagnosis of this condition is important because treatment is available and can result in clinical improvement.(1.)
authors.affiliation: Pediatric Residency Training Program, maria.rahmandar@cchmc.org rizwan.hamid@vanderbilt.edu.
authors.forename: Maria H
authors.initials: MH
authors.lastname: Rahmandar
authors.affiliation: Division of Medical Genetics and Genomic Medicine, and.
authors.forename: Amanda
authors.initials: A
authors.lastname: Bawcom
authors.affiliation: Division of Adolescent and Young Adult Health, Department of Pediatrics, Monroe Carell Jr Children's Hospital at Vanderbilt University, Nashville, Tennessee.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Romano
authors.affiliation: Division of Medical Genetics and Genomic Medicine, and maria.rahmandar@cchmc.org rizwan.hamid@vanderbilt.edu.
authors.forename: Rizwan
authors.initials: R
authors.lastname: Hamid
mesh_terms: D000293:Adolescent; D000855:Anorexia / Q000175:diagnosis / Q000209:etiology*; D002352:Carrier Proteins / Q000235:genetics; D002650:Child Abuse, Sexual / Q000175:diagnosis; D015897:Comorbidity; D003299:Cooperative Behavior; D003937:Diagnosis, Differential; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis; D005260:Female; D006580:Genetic Carrier Screening; D006801:Humans; D013287:Illicit Drugs; D033183:Interdisciplinary Communication; D010088:Oxidoreductases; D011618:Psychotic Disorders / Q000175:diagnosis / Q000209:etiology*; D019966:Substance-Related Disorders / Q000175:diagnosis; D014805:Vitamin B 12 / Q000627:therapeutic use; D014806:Vitamin B 12 Deficiency / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics
chemical_list: D002352:Carrier Proteins; D013287:Illicit Drugs; C508359:MMACHC protein, human; D010088:Oxidoreductases; D014805:Vitamin B 12
keywords: adolescent; anorexia; ataxia; cobalamin C deficiency; psychotic disorder