Extremely high mutation load of the mitochondrial 8993 T>G mutation in a newborn: implications for prognosis and family planning decisions

The propositus presented with hypotonia, respiratory failure, and seizures in the newborn period and was found to have severe hyperlactacidemia and a hypertrophic heart. He carried a de novo pathogenic mutation (m.8993 T>G) in the gene encoding subunit 6 of the mitochondrial ATP synthase ( MTATP6 ). Although the lactate concentration in serum normalized and the proband recovered after a short period at the neonatal intensive care unit, his ultimate motor and cognitive development was poor. Brain MRI at the age of 6 months showed bilaterally signal abnormalities in the caudate nucleus, putamen, thalamus, and mesencephalon. He died at the age of 9 months. The difficulty in genetic counseling in families with a maternal mitochondrial mutation disorder is emphasized. Conclusion : Here, we report on a neonate with the m.8993 T>G mutation and emphasize implications of mtDNA disorders on family planning decisions.