Enzymopenic Congenital Methemoglobinemia in Children of the Republic of Sakha (Yakutia).

Type I congenital methemoglobinemia is an autosomal recessive disorder. A high frequency of congenital methemoglobinemia has been reported among Native Americans inhabiting the Yukon-Kuskokwim Delta. Other rare cases of congenital methemoglobinemia of types I and II have been reported in Japan and other countries. In Russia-namely, in Yakutia-a high frequency of type I congenital methemoglobinemia has been reported. In 2009, the Consultation Polyclinic of the Pediatric Center in Yakutsk city established a registry of children with congenital methemoglobinemia. In total, 43 patients were registered between 2005 and 2009. The median methemoglobin level was 13.5% (ranging between 4.2% and 33.9%) and physical examination revealed cyanosis of the skin and mucus membranes. There were significant positive relationships between percentage of methemoglobin and erythrocyte count, hemoglobin concentration, and hematocrit among male patients, consistent with an upregulation of the hypoxic response. The prevalence per 100,000 children ranged from 12.7 to 47.0 in 3 geographic regions of Yakutia. Further research is needed to clarify the clinical consequences of congenital methemoglobinemia in the children of Yakutia and the reasons for the high variability in the prevalence of the condition.