Congenital methemoglobinemia and abnormal hemoglobin M variant in a newborn with cyanosis

Abstract

Congenital methemoglobinemia, especially caused by pathological hemoglobin M, is an extremely rare cause of cyanosis in newborns. The time to onset and severity of clinical manifestations in hemoglobin M disease depends on which globin chain the mutation occurred in.Purpose. To present the case of congenital methemoglobinemia associated with hemoglobin M disease, not recognized in the neonatal period, to summarize the data on diagnosis, therapy, and prognosis for this pathology.Clinical case. In a full-term child without organ pathology, the development of diffuse cyanosis in the early neonatal period, a decrease in pSO2 of 70%, resistant to oxygen therapy, and increasing anemia were noted. The level of methemoglobin is up to a maximum of 17%. A decrease in the level of methemoglobin to 5.7% and stabilization of pSO2 >90% were obtained after two transfusions of erythrocyte suspension. No pathological forms of hemoglobin were detected during electrophoresis on the 5th day of life. Repeated electrophoresis at the age of 5 months revealed a pathological hemoglobin fraction of 8.9% corresponding to hemoglobin M Iwate. During the first year of observation, the growth and development of the child corresponds to the age norm. Stable acrocyanosis. Methemoglobin in the blood remains at the level of 8.7–8.9% without specific therapy for the last 6 months.Conclusion. The diagnosis of congenital methemoglobinemia due to the presence of defective hemoglobin M (M-hemoglobinopathy) was established basing on the high persistent level of methemoglobin (9–12%) and hemoglobin electrophoresis identified an abnormal hemoglobin M (HbM Iwate) variant.