ABSTRACT
INTRODUCTION: Phosphoglycerate mutase deficiency (PGAM) is a rare metabolic myopathy that results in terminal block in glycogenolysis. Clinically, patients with PGAM deficiency are asymptomatic, except when they engage in brief, strenuous efforts, which may trigger myalgias, cramps, muscle necrosis, and myoglobinuria. An unusual pathologic feature of PGAM deficiency is the association with tubular aggregates. METHODS: We report an African-American patient from Panama with partial deficiency of PGAM who presented with asymptomatic elevation of creatine kinase levels and tubular aggregates on muscle biopsy. RESULTS: Muscle biopsies showed subsarcolemmal and sarcolemmal tubular aggregates in type 2 fibers. Muscle PGAM enzymatic activity was decreased and gene sequencing revealed a heterozygous mutation in codon 78 of exon 1 of the PGAM2 gene, which is located on the short arm of chromosome 7. CONCLUSIONS: PGAM deficiency has been reported in 14 patients, 9 of whom were of African-American ethnicity, and in 5 (36%) tubular aggregates were seen on muscle biopsy. Contrary to previously reported cases, our patient was initially asymptomatic. This further expands the PGAM deficiency phenotype.
Subject(s)
Muscle Cramp/pathology , Muscle Weakness/pathology , Muscle, Skeletal/pathology , Phosphoglycerate Mutase/deficiency , Adult , Humans , Male , Muscle Cramp/enzymology , Muscle Cramp/genetics , Muscle Weakness/enzymology , Muscle Weakness/genetics , Muscle, Skeletal/enzymology , Phosphoglycerate Mutase/genetics , Phosphoglycerate Mutase/metabolismABSTRACT
The objective of the study was to establish the safety and pharmacodynamics of escalating dosages of sodium phenylbutyrate (NaPB) in participants with ALS. Transcription dysregulation may play a role in the pathogenesis of ALS. Sodium phenylbutyrate, a histone deacetylase inhibitor, improves transcription and post-transcriptional pathways, promoting cell survival in a mouse model of motor neuron disease. Forty research participants at eight sites enrolled in an open-label study. Study medication was increased from 9 to 21 g/day. The primary outcome measure was tolerability. Secondary outcome measures included adverse events, blood histone acetylation levels, and NaPB blood levels at each dosage. Twenty-six participants completed the 20-week treatment phase. NaPB was safe and tolerable. No study deaths or clinically relevant laboratory changes occurred with NaPB treatment. Histone acetylation was decreased by approximately 50% in blood buffy-coat specimens at screening and was significantly increased after NaPB administration. Blood levels of NaPB and the primary metabolite, phenylacetate, increased with dosage. While the majority of subjects tolerated higher dosages of NaPB, the lowest dose (9 g/day), was therapeutically efficient in improving histone acetylation levels.
Subject(s)
Amyotrophic Lateral Sclerosis/drug therapy , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/pharmacokinetics , Histone Deacetylase Inhibitors , Phenylbutyrates/administration & dosage , Phenylbutyrates/pharmacokinetics , Aged , Anticonvulsants/administration & dosage , Anticonvulsants/blood , Dose-Response Relationship, Drug , Drug Therapy, Combination , Enzyme Inhibitors/adverse effects , Female , Histone Deacetylases/metabolism , Humans , Male , Middle Aged , Motor Neurons/drug effects , Motor Neurons/enzymology , Phenylacetates/administration & dosage , Phenylacetates/blood , Phenylbutyrates/adverse effectsABSTRACT
The past decade of research in amyotrophic lateral sclerosis has contributed to a greater understanding of the disease process, the development of relevant animal models, and the identification of several therapeutic approaches that may delay disease progression. Completed and ongoing clinical trials and the process of selecting drugs for clinical trials are presented.
