TIMM8A is a mitochondrial intermembrane chaperone that is involved in the import and insertion of some multi-pass transmembrane proteins into the mitochondrial inner membrane. It also acts as a chaperone-like protein that protects the hydrophobic precursors from aggregation and guide them through the mitochondrial intermembrane space. TIMM8A is probably necessary for normal neurologic development. TIMM8A is a heterohexamer composed of three TIMM8A and three TIMM13 subunits, named soluble 70KD complex. It associates with the TIMM22 complex. It is located at the mitochondrion inner membrane and is highly expressed in fetal and adult brain, followed by fetal lung, liver and kidney. Defects in TIMM8A cause Mohr-Tranebjaerg syndrome (MTS) also known as dystonia-deafness syndrome (DDS) or X-linked progressive deafnes type 1 (DFN-1). This is a recessive neurodegenerative syndrome characterised by progressive deafness, dystonia, spasticity, dysphagia, mental deterioration, paranoia and cortical blindness. Defects in TIMM8A are also the cause of Jensen syndrom, also known as opticoacoustic nerve atrophy with dementia. This is an X-linked disease characterised by deafness, blindess and muscle weakness.