A novel in-frame deletion mutation in a case of lactate dehydrogenase (LD) H subunit deficiency showing an atypical LD isoenzyme pattern in serum and erythrocytes

• Published in: Clinical biochemistry 1999-03, Vol.32 (2), p.137-141
• Main Authors: Sudo, Kayoko, Maekawa, Masato, Houki, Nobuyuki, Okuda, Takanari, Akizuki, Setsuko, Magara, Tadao, Kawano, Kazuhiro
• Format: Article
• Language: English
• Subjects: Adult; Erythrocytes - enzymology; expression at mRNA level; glycolytic pathway; Humans; Isoenzymes - deficiency; Isoenzymes - genetics; L-Lactate Dehydrogenase - blood; L-Lactate Dehydrogenase - deficiency; L-Lactate Dehydrogenase - genetics; Male; Sequence Deletion; substrate-contact domain; three-dimensional change
• ISSN: 0009-9120; 1873-2933
• DOI: 10.1016/S0009-9120(98)00097-6

Objective: We report a case showing an atypical lactate dehydrogenase (LD) isoenzyme pattern involving deficiency only of LD-1 and LD-2 in serum and erythrocytes. LD activity in serum from this patient was extremely low, similar to complete LD-H deficiency, and also that in erythrocytes was low. Design: The DNA fragment containing exon 1 through 7 of the LD-H gene were amplified by PCR and directly sequenced. Total RNA was prepared from venous blood and the proportion of LD-H cDNA to total LD cDNA was semiquantified. Results: Genetic analysis by DNA sequencing detected a three base deletion (AAT) at codon 220 of exon 5, which caused a deletion of one asparagine. The present case did not show reduced LD-H expression at the mRNA level in whole blood. Residue 220 is involved in turning β-J to α 1-G and is not buried in the interior of the protein. The novel homozygous in-frame deletion mutation at codon 220 may cause a three-dimensional change of the subunit-binding domain.