Perinatal central cyanosis with a clinically favourable outcome: HbM-Iwate

Background:

The HbM-Iwate occurs rarely; mainly in the Iwate region of Japan, and a few cases are reported in central Europe, India, South America. A mutation in the alpha haemoglobin (Hb) causes the haeme group to oxidise and form MetHb. It is responsible for cyanosis and low percutaneous oxygen saturation values. The mutant alpha chain of HbM-Iwate structurally interacts with and lowers the Hb oxygen affinity of the beta globin, which in turn allows oxygen to dissociate from the Hb more readily. Hence no severe oxygen insufficiency exists.

Case report:

A female term neonate was born in a peripheral hospital. The pregnancy was without complications, no intake of medications or other drugs. Spontaneous birth, Apgar 9/9/9, umbilical artery pH 7.21, birth weight 3810 g. In the first hour of life, central cyanosis was observed. Percutaneous saturation was at 60 – 70%, and remained around 65% with oxygen supplementation for the next 5 days. The arterial blood gas analyses showed a constant saturation of 78 – 87% and a composition of 10% MetHb and SulfHb. An echocardiography and chest x-ray were performed without pathological findings. The haemoglobin analysis in HPLC showed no abnormalities, oxygen affinity for HbF was lowered, mass spectroscopy indicated an abnormal alpha globin, and the sequencing of alpha globin gene showed a heterozygous mutation at the position alpha 1 CD87 (C->T). In literature this mutation is described as the HbM-Iwate variant. The mutation was not found in the child's parents. Clinically the child continued to display a central cyanosis in the first five years of life, with no other pathological findings and a normal childhood development.

Conclusion:

This case illustrates that in presentation with congenital central cyanosis life threatening causes have to be ruled out first (cardiological, pulmonary, dangerous MetHb induced by enzyme deficiencies, drugs or toxins). If by further testing, the HbM-Iwate variant is diagnosed, it has a favourable prognosis, with mainly cosmetic issues of cyanosis. However, it is important to document the HbM-Iwate in the patient history, especially for future anaesthesia procedures.