Hemoglobin Beth Israel. A mutant causing clinically apparent cyanosis.

Area of Science:

• Hematology
• Biochemistry
• Genetics

Background:

• Cyanosis is a bluish discoloration of the skin and mucous membranes due to low oxygen levels in the blood.
• Abnormal hemoglobin variants can affect oxygen transport and lead to various clinical manifestations.

Observation:

• An otherwise healthy adolescent presented with overt cyanosis despite normal blood counts and oxygen tension.
• The patient was found to be a heterozygous carrier of Hemoglobin Beth Israel.

Findings:

• Hemoglobin Beth Israel exhibits a very low oxygen affinity, characterized by a right-shifted oxygen dissociation curve (P50 = 88 mm Hg).
• Despite normal arterial oxygen tension (97 mm Hg), arterial oxygen saturation was significantly reduced (63%).
• The abnormal hemoglobin demonstrated a normal Bohr effect but impaired oxygen binding.

Implications:

• Unexplained cyanosis, especially with normal arterial oxygen tension, warrants investigation for abnormal hemoglobin variants.
• Identifying abnormal hemoglobins like Hemoglobin Beth Israel can aid in diagnosis and potentially avoid invasive procedures.
• This case highlights the importance of considering hemoglobinopathies in the differential diagnosis of cyanosis.