The BCS1L gene at 2q34-36 codes for mitochondrial chaperone BCS1 which is a 419 amino- acid protein chaperone necessary for the assembly of mitochondrial respiratory chain complex III. It also plays a role in the maintenance of mitochondrial tubular networks and formation of the LETM1 complex. Mutations of BCS1L cause:
- Bjornstad syndrome
- pili torti
- sensorineural deafness
- Complex III (ubiquinol cytochrome c reductase) deficiency see Mitochondrial diseases
- Hepatic failure
- GRACILE syndrome see Mitochondrial diseases
There is a strong correlation with these mutations and production of reactive oxygen and the Bjornstad syndrome is presently regarded as the mildest form of disease suggesting that ear hair and ordinary hair follicle tissues are particularly sensitive to free oxygen which may explain certain drug side-effects such as with aminoglycosides.