Hb M-Iwate in an Indian family

High performance liquid chromatography in a newborn girl with congenital cyanosis and a unilateral cleft palate revealed a variant hemoglobin with retention time of 4.8 min, similar to hemoglobin Q-India. Since hemoglobin Q-India did not explain the cyanosis, further investigations were initiated.

Sequencing of α-globin genes revealed hemoglobin M-Iwate ([α87 (F8) His → Tyr]) that was confirmed on restriction enzyme analysis.

Hemoglobin M-Iwate is a rare methemoglobinemic variant formed due to a point mutation in the α-globin gene. Primarily reported from the Iwate prefecture of Japan, there have been occasional case reports from other regions as well. Inherited methemoglobinemia finds only rare mention in Indian literature while hemoglobin M-Iwate has not been reported from India.

This case illustrates the step-wise logical diagnostic approaches necessary to elucidate the cause of methemoglobinemia in an otherwise healthy child with cyanosis.