Recurrent episodes of myoglobinuria, mental retardation and seizures but no hemolysis in two brothers with phosphoglycerate kinase deficiency

•Two brothers with recurrent rhabdomyolysis, mental retardation and seizures were reported.•There was markedly decreased PGK activity in red blood cells but no hemolysis.•DNA sequencing revealed a novel c.756 + 3A > G splice site mutation.•Multiple aberrant transcripts were identified.•Comparison with other patients with similar mutations suggests a possible phenotype–genotype correlation.