Accessory subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I), that is believed not to be involved in catalysis. Complex I functions in the transfer of electrons from NADH to the respiratory chain. The immediate electron acceptor for the enzyme is believed to be ubiquinone. Complex I is composed of 45 different subunits. The disease is caused by variants affecting the gene represented in this entry. Belongs to the complex I NDUFB8 subunit family.