Glossary

trimester – a 12 week period of a pregnancy. Different periods during pregnancy are commonly referred to as the first, second and third trimester.

diagnosis – identifying the cause of an illness.

CSF – cerebral spinal fluid – the fluid that circulates around the brain and spinal column.

revertant mutation – this term is used in two ways.

Firstly when referring to a genetic change that shows the virus is returning from a drug resistant mutation back to a wild-type genotype. This can sometimes take several stages. For example, T215E/D/E and S are revertant mutations that can indicate the drug resistant mutation T215Y is being replaced by wild-type (i.e. T215T).

It can also refer to the fitness of a virus. A revertant mutation can refer to an additional mutation that allows the virus to regain viral fitness (most drug mutations also make the vurs less fit). The second example is called a compensatory mutation as is compensates for the reduced fitness caused by the first mutation.

prenatal – before birth. The time in which the foetus (developing baby) grows in the uterus.