Twenty-one had Alpers syndrome , the commonest severe POLG1 autosomal recessive phenotype , comprising hepatoencephalopathy and often mtDNA depletion .
O O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature O O O O B-GeneOrGeneProduct O O O O O B-DiseaseOrPhenotypicFeature O O O O O