A SPLICE JUNCTION MUTATION IN A NEW MYOPATHIC VARIANT OF PHOSPHOGLYCERATE KINASE-DEFICIENCY (PGK NORTH-CAROLINA)

We report on a 12-year-old boy with the myopathic form of phosphoglyce rate kinase (PGK) deficiency, and unique kinetic and physical characte ristics of the mutant enzyme (PGK North Carolina). A G-to-T substituti on at the 5' end of intron 4 was identified in the PGK gene of this pa tient. The mutation destroys the consensus sequence GT at the 5' splic e junction of the intron. Activation of a cryptic splice site within i ntron 4 causes the insertion into the transcript of a 30-bp fragment a t the 5' end of intron 4. This insertion results in ten additional ami no acids within the ''nose'' of the PGK molecule, but does not generat e a frameshift or a premature stop codon.