Very rare. Abnormality of hemoglobin due to a mutation of the HBA1 gene resulting in the replacement of histidine by aspartic acid in position 87 on the α chain of hemoglobin .
This mutation results in:

-        microcytic anemia with moderate hemolysis

-        a peak absorbance of light by oxyhemoglobin Bonn at 668 nm, close to the absorbance of light by  oxyhemoglobin A at 660 nm, one of the wavelengths used by the pulse oximeters: SpO2 is therefore artificially low

Anesthetic implications: 

erroneously low measurement of SpO2 (pulse oximetry): maximum value at 91% in pure oxygen; monitoring by measurement of transcutaneous paO2 or the blood gases.

References:

•        Zur B, Ludwig M, Stoffel-Wagner B. 
  A novel hemoglobin, Bonn, causes falsely decreased oxygen saturation measurements in pulse oximetry.
  Clin Chem 2008; 54: 594-6.

Updated: August 2017