TWNK and mitochondrial DNA depletion syndrome 7 (hepatocerebral type): Hypergonadotrophic hypogonadism has been reported in the context of mitochondrial neurogastrointestinal encephalopathy (MNGIE) (106, 107) and/or infantile onset spinocerebellar ataxia caused by recessive variants in the TWNK gene, which encodes for mtDNA helicase Twinkle (108).