Jamil Syed Furrukh, Alhawsawi Kawther Ibrahim, Alrefaei Shahad Mohammed
Department of Pediatrics, King Abdullah Specialized Children's Hospital, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia.
Department of Clinical Affairs, College of Medicine College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.
J Family Med Prim Care. 2025 May;14(5):2065-2069. doi: 10.4103/jfmpc.jfmpc_1839_24. Epub 2025 May 31.
This case report highlights an unusual presentation of transcobalamin 2 (TCN2) deficiency. It is a rare autosomal recessive disorder. In this case, we present a three-month-old child with prolonged fever and pancytopenia. Initial investigations could not reach a diagnosis. Subsequent investigations revealed normal serum vitamin B12 levels and elevated homocysteine levels, suggesting a vitamin B12 metabolic disorder. Genetic testing confirmed the presence of pathogenic variations in the transcobalamin 2 gene that led to establishing the diagnosis of transcobalamin 2 deficiency. The initiation of vitamin B12 supplementation led to the resolution of the patient's symptoms and the normalization of hematological parameters. Recognizing transcobalamin 2 deficiency as a possible cause of prolonged fever and low blood cell counts (pancytopenia) led to further specialized testing and genetic analysis. Considering this rare condition as a potential diagnosis, even when vitamin B12 levels appear normal is crucial. Comprehensive lab tests and genetic testing are essential to correctly identify these uncommon yet treatable disorders and guide appropriate treatment.
本病例报告突出了转钴胺素2（TCN2）缺乏症的一种不寻常表现。它是一种罕见的常染色体隐性疾病。在本病例中，我们介绍了一名三个月大的儿童，伴有持续发热和全血细胞减少。初步检查未能确诊。随后的检查显示血清维生素B12水平正常，但同型半胱氨酸水平升高，提示维生素B12代谢紊乱。基因检测证实转钴胺素2基因存在致病变异，从而确诊为转钴胺素2缺乏症。补充维生素B12后患者症状得到缓解，血液学参数恢复正常。认识到转钴胺素2缺乏症可能是持续发热和血细胞计数低（全血细胞减少）的原因，促使进行了进一步的专业检测和基因分析。即使维生素B12水平看似正常，将这种罕见疾病视为潜在诊断也至关重要。全面的实验室检查和基因检测对于正确识别这些罕见但可治疗的疾病并指导适当治疗至关重要。
