This link between genotype and phenotype, as it relates to long-chain fatty acid β-oxidation, has been previously demonstrated in very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiencies, which present as three clinically heterogeneous phenotypes that are eerily similar to those exhibited by FKRP-related dystroglycanopathies49,50. The gene discussed is FKRP; the disease is very long chain acyl-CoA dehydrogenase deficiency.