AI Summary & Key Takeaways
AI InsightThis untreatable, rare condition must be included in the differential diagnosis of patients with unexplained cyanosis and high methemoglobin levels, and genetic counseling must be provided to the family, because of its severity and 25% recurrence rate.
📌 3 Key Takeaways
Abstract
Congenital methemoglobinemia is a rare cause of cyanosis that is characterized by increased methemoglobin levels and caused by mutations in the cytochrome B5 reductase 3 (CYB5R3) gene resulting in deficiencies of the nicotinamide adenine dinucleotide-cytochrome b5 reductase enzyme. The congenital disease has two types: type I, in which the enzyme deficiency occurs only in the erythrocytes, and type II, in which all tissues are affected. Accordingly, cyanosis is the sole clinical manifestation in type I, whereas cyanosis is accompanied by such severe neurological findings as intellectual disability, microcephaly, generalized dystonia, and movement disorders. In this study, a case who presented with respiratory distress was found to have high methemoglobin levels and was diagnosed with type II congenital methemoglobinemia due to the presence of neurological findings was presented. The patient's treatment was adjusted, the methemoglobin level was reduced, and cyanosis regressed, but no change was observed in neurological findings. This untreatable, rare condition must be included in the differential diagnosis of patients with unexplained cyanosis and high methemoglobin levels, and genetic counseling must be provided to the family, because of its severity and 25% recurrence rate.
Özet
Konjenital methemoglobinemi, methemoglobin düzeyinde artışla seyreden, nadir siyanoz sebeplerindendir. Hastalıktan sorumlu olan nikotinamid adenin dinükleotit sitokrom b5 redüktaz enzimi eksikliğine sebep olan sitokrom B5 redüktaz 3 (CYB5R3) gen mutasyonlarıdır. Konjenital hastalığın iki tipi vardır; tip I’de sadece eritrositlerde enzim eksikliği görülürken, tip II’de tüm dokular etkilenir. Buna bağlı olarak tip I’de siyanoz görülen tek klinik bulgu iken tip II’de hafif siyanozun yanında bilişsel yetersizlik, mikrosefali, jeneralize distoni, hareket bozuklukları gibi ciddi nörolojik bulgular eşlik eder. Bu çalışmada, solunum sıkıntısı yakınması ile başvuran, methemoglobin düzeyi yüksek saptanan, nörolojik bulguların eşlik etmesi sebebi ile tip II konjenital methemoglobinemi tanısı alan olgu sunuldu. Hastanın tedavisi düzenlendi, methemoglobin düzeyi düşürüldü, siyanoz geriledi, ancak nörolojik bulgularda değişiklik görülmedi. Tedavisi olmayan bu nadir hastalık, açıklanamayan siyanozu olup methemoglobin düzeyi yüksek saptanan hastaların ayırıcı tanıları arasında yer almalı ve hastalığın şiddeti ve %25 nüks oranı nedeniyle aileye genetik danışmanlık verilmelidir.