An Electrophoretic Variant of the Human Lactate Dehydrogenase H Subunit

Glutamic Acid to Lysine Substitution at Codon 230

Abstract

This report describes a patient with an electrophoretic variant of lactate dehydrogenase H subunit. The LDH activity in serum was lower than normal (patient 125 U/L: reference range 261-483 U/L). The LDH isozyme pattern was unique with a broad band spanning the LDH1 to LDH4 regions. We also performed electrophoresis of serum and red blood cell lysate using a discontinuous buffer system. The band 56 patterns obtained were consistent with the existence of an electrophoretic variant of the B locus of Lactate dehydrogenase. By genetic analysis we were able to confirm that the patient is heterozygous for the mutation, causing a substitution of Glutamic acid (GAA) to Lysine (AAA) at codon 230.